Chapter L: TIGRINUM, Ker. (TIGER LILY.) Tall, pubescent above; leaves scattered, (2)

1. ARISAEMA, Martius. INDIAN TURNIP. DRAGON ARUM.

Spathe convolute below and mostly arched above. Flowers monoecious or by abortion dioecious, covering only the base of the spadix, which is elongated and naked above. Floral envelopes none. Sterile flowers above the fertile, each of a cluster of almost sessile 2--4-celled anthers, opening by pores or chinks at the top. Fertile flowers consisting each of a 1-celled ovary, tipped with a depressed stigma, and containing 5 or 6 orthotropous ovules erect from the base of the cell; in fruit a 1--few-seeded scarlet berry. Embryo in the axis of albumen.--Low perennial herbs, with a tuberous rootstock or corm, sending up a simple scape sheathed with the petioles of the simple or compound veiny leaves. (Name from [Greek: a)ri/s], a kind of _arum_, and [Greek: ai~(ma], _blood_, from the spotted leaves of some species.)

1. A. triphyllum, Torr. (INDIAN TURNIP.) _Leaves mostly 2, divided into 3 elliptical-ovate pointed leaflets; spadix mostly dioecious, club-shaped_, obtuse, much shorter than the spathe, which is flattened and incurved-hooded at the ovate-lanceolate, pointed summit.--Rich woods, N. Scotia to Fla., west to Minn. and E. Kan. May.--Corm turnip-shaped, wrinkled, farinaceous, with an intensely acrid juice; spathe with the petioles and sheaths green, or often variegated with dark purple and whitish stripes or spots.

2. A. Dracontium, Schott. (GREEN DRAGON. DRAGON-ROOT.) _Leaf usually solitary, pedately divided_ into 7--11 oblong-lanceolate pointed leaflets; _spadix often androgynous, tapering to a long and slender point_ beyond the oblong and convolute pointed greenish spathe.--Low grounds, N. Eng. to Fla., west to Minn., E. Kan., and Tex. June.--Corms clustered; petiole 1--2 deg. long, much longer than the peduncle.

2. PELTANDRA, Raf. ARROW ARUM.

Spathe elongated, convolute throughout or with a dilated blade above. Flowers monoecious, thickly covering the long and tapering spadix throughout (or only its apex naked). Floral envelopes none. Anthers sessile, naked, covering all the upper part of the spadix, each of 5 or 6 cells imbedded in the margin of a thick and shield-shaped connective, opening by a terminal pore. Ovaries at the base of the spadix, each surrounded by 4--5 staminodia connate into a cup, 1-celled, bearing 1--few amphitropous or nearly orthotropous ovules at the base; stigma almost sessile. Fruit a leathery or fleshy berry, 1--3-seeded. Seed obovate, surrounded by a tenacious jelly, the base empty, the upper part filled with a large and fleshy spherical embryo; no albumen.--Stemless herbs, with arrow-shaped leaves and simple scapes from a thick-fibrous or subtuberous root. Fruit in a globose cluster, enclosed by the persistent fleshy base of the spathe. (Name from [Greek: pe/lte], _a target_, and [Greek: a)ne/r], for _stamen_, from the shape of the latter.)

1. P. undulata, Raf. Root of thick tufted fibres; scape 1--11/2 deg. high, about equalling the leaves; basal lobes of the leaves rather long and often acutish; spathe convolute throughout, wavy on the margin, mostly green, 4--7' long; sterile portion of the spadix several times longer than the pistillate; ovules several; fruit green; seeds 1--3. (P. Virginica, _Kunth_, and most authors.)--Shallow water, New Eng. to Fla., west to Mich. and Ind. June.

2. P. alba, Raf. Rootstock tuberous, covered with thick-fleshy roots and propagating by offshoots; lobes of the leaves mostly short and broad, obtuse; spathe 3--4' long, the blade broader, acuminate, somewhat expanded, white; sterile part of the spadix scarcely longer than the pistillate; ovules and seeds solitary; berry scarlet, 5--6'' long. (P. Virginica, _Schott._ Xanthosoma sagittifolia, _Chapm._, not _Schott._ Caladium glaucum, _Ell._ Arum Virginicum, _L._, in part?)--Marshes, S. Va.(?) and N. C. to Fla.

3. CALLA, L. WATER ARUM.

Spathe open and spreading, ovate (abruptly pointed, the upper surface white), persistent. Spadix oblong, entirely covered with flowers; the lower perfect and 6-androus; the upper often of stamens only. Floral envelopes none. Filaments slender; anthers 2-celled, opening lengthwise. Ovary 1-celled, with 5--9 erect anatropous ovules; stigma almost sessile. Berries (red) distinct, few-seeded. Seeds with a conspicuous rhaphe and an embryo nearly the length of the hard albumen.--A low perennial herb, growing in cold bogs, with a long creeping rootstock, bearing heart-shaped long-petioled leaves, and solitary scapes. (An ancient name, of unknown meaning.)

1. C. palustris, L.--Cold bogs, N. Scotia to N. J., west to Mich. and Minn., and northward. June.--Seeds surrounded with jelly. (Eu.)

4. SYMPLOCARPUS, Salisb. SKUNK CABBAGE.

Spathe hooded-shell-form, pointed, very thick and fleshy, decaying in fruit. Spadix globular, short-stalked, entirely and densely covered with perfect flowers, their 1-celled or abortively 2-celled ovaries immersed in the fleshy receptacle. Sepals 4, hooded. Stamens 4, opposite the sepals, with at length rather slender filaments; anthers extrorse, 2-celled, opening lengthwise. Style 4-angled and awl-shaped; stigma small. Ovule solitary, suspended, anatropous. Fruit a globular or oval mass, composed of the enlarged and spongy spadix, enclosing the spherical seeds just beneath the surface, which is roughened with the persistent fleshy sepals and pyramidal styles. Seeds filled by the large globular and fleshy corm-like embryo, which bears one or several plumules at the end next the base of the ovary; albumen none.--Perennial herb, with a strong odor like that of the skunk, and also somewhat alliaceous; a very thick rootstock, bearing a multitude of long and coarse fibrous roots, and a cluster of very large and broad entire veiny leaves, preceded in earliest spring by the nearly sessile spathes, which barely rise out of the ground. (Name from [Greek: symploke/], _connection_, and [Greek: karpo/s], _fruit_, in allusion to the coalescence of the ovaries into a compound fruit.)

1. S. foetidus, Salisb. Leaves ovate, cordate, becoming 1--2 deg. long, short-petioled; spathe spotted and striped with purple and yellowish-green, ovate, incurved; fruit (in autumn) 2--3' in diam., in decay shedding the bulblet-like seeds, which are 4--6'' long.--Bogs and moist grounds, N. Scotia to N. C., west to Minn. and Iowa.

5. ORONTIUM, L., GOLDEN-CLUB.

Spathe incomplete and distant, merely a leaf-sheath investing the lower part of the slender scape, and bearing a small and imperfect bract-like blade. Flowers crowded all over the narrow spadix, perfect; the lower with 6 concave sepals and 6 stamens; the upper ones with 4. Filaments flattened; anthers 2-celled, opening obliquely lengthwise. Ovary 1-celled, with an anatropous ovule; stigma sessile, entire. Fruit a green utricle. Seed without albumen. Embryo thick and fleshy, "with a large concealed cavity at the summit, the plumule curved in a groove on the outside." (_Torr._)--An aquatic perennial, with a deep rootstock, long-petioled and entire oblong and nerved floating leaves, and the spadix terminating the elongated scape; its rather club-shaped emersed apex as thick as the spadix. (Origin of the name obscure.)

1. O. aquaticum, L.--Ponds, Mass. to Fla. May.

6. ACORUS, L. SWEET FLAG. CALAMUS.

Spadix cylindrical, lateral, sessile, emerging from the side of a simple 2-edged scape which resembles the leaves, densely covered with perfect flowers. Sepals 6, concave. Stamens 6; filaments linear; anthers kidney-shaped, 1-celled, opening across. Ovary 2--3-celled, with several pendulous orthotropous ovules in each cell; stigma minute. Fruit at length dry, gelatinous inside, 1--few-seeded. Embryo in the axis of albumen.--Pungent aromatic plants, especially the thick creeping rootstocks (_calamus_ of the shops), which send up 2-edged sword-like leaves, and scapes somewhat like them, bearing the spadix on one edge; the upper and more foliaceous prolongation sometimes considered as a kind of open spathe. ([Greek: A)/koras], the ancient name, of no known meaning.)

1. A. Calamus, L. Scape leaf-like and prolonged far beyond the (yellowish-green) spadix.--Margins of rivulets, swamps, etc., N. Scotia to Fla., west to Minn., Iowa, and E. Kan.

ORDER 124. LEMNACEAE. (DUCKWEED FAMILY.)

_Minute stemless plants, floating free on the water, destitute of distinct stem and foliage, being merely a frond, producing one or few monoecious flowers from the edge or upper surface, and commonly hanging roots from underneath; ovules rising from the base of the cell. Fruit a 1--7-seeded utricle. Seed large; the apex or radicular extremity of the seed-coat separable as an operculum or lid_ (as in Cabomba, etc.). _Embryo straight, surrounded by fleshy or sometimes very scanty albumen._--The simplest, and some of them the smallest of flowering plants, propagating by the proliferous growth of a new individual from a cleft in the edge or base of the parent frond, remaining connected for some time or separating, also by autumnal fronds in the form of minute bulblets, which sink to the bottom of the water, but rise and vegetate in spring; the flowers (in summer) and fruit scarce, in some species hardly ever seen. Frond more or less cavernous; the upper surface furnished with stomata.--These plants may be regarded as very simplified Araceae.

1. Spirodela. Frond 7--11-nerved, with several rootlets.

2. Lemna. Frond 1--5-nerved, with a single rootlet.

3. Wolffia. Frond thick, very minute (1/4--{2/3}' broad), without rootlets.

1. SPIRODELA, Schleiden.

Anther-cells bilocellate by a vertical partition and longitudinally dehiscent. Ovules 2. Frond 7--11-nerved or more; rootlets several, with axile vascular tissue. Otherwise as Lemna. (From [Greek: spei~ra], _a cord_, and [Greek: de~los], _evident_.)

1. S. polyrrhiza, Schleid. Fronds round-obovate (2--4'' long), thick, purple and rather convex beneath, dark green above, palmately (mostly 7-) nerved. (Lemna polyrrhiza, _L._)--Very common in ponds and pools, throughout N. Am., but very rarely found in flower or fruit. (Eu.)

2. LEMNA, L. DUCKWEED. DUCK'S-MEAT.

Flowers produced from a cleft in the margin of the frond, usually three together surrounded by a spathe; two of them staminate, consisting of a stamen only; the other pistillate, of a simple pistil; the whole therefore imitating a single diandrous flower. _Ster. Fl._ Filament slender; anther 2-celled, didymous; the cells dehiscent transversely; pollen-grains large, spherical, muricate. _Fert. Fl._ Ovary 1-celled; style and truncate or funnel-shaped stigma simple. Ovules and seeds 1--7.--Fronds 1--5-nerved, producing a single rootlet beneath (which is destitute of vascular tissue), proliferous from a cleft in the margin toward the base, and at length stipitate; the tissue abounding with bundles of rhaphides. (An old Greek name of uncertain meaning.)

[*] _Ovule solitary, orthotropous or nearly so; frond 1--3-nerved, thin._

[+] _Fronds oblong, stalked at base, remaining connected._

1. L. trisulca, L. Fronds oblong to oblong-lanceolate (6--9'' long), attenuate at base into a slender stalk, denticulate at the tip, very obscurely 3-nerved, often without rootlets, usually several series of offshoots remaining connected; spathe sac-like; seeds ovate, amphitropous, with small round operculum.--Ponds and springy places, N. Scotia to N. J., west to the Pacific. (Eu.)

[+][+] _Fronds oblong to elliptical or round-ovate, sessile, soon separating._

2. L. Valdiviana, Philippi. _Fronds elliptic-oblong_, small (about 1'' long), rather thick, usually somewhat falcate, _obscurely 1-nerved; spathe broad-reniform_; utricle long-ovate, pointed by the long style; _seed orthotropous_, oblong, _with a prominent acute operculum_. (L. Torreyi, _Austin._)--Pools, N. J. and southward, westward across the continent. (S. Am.)

3. L. perpusilla, Torr. _Fronds obovate or roundish-obovate_, oblique (1--11/2'' long), _obscurely 3-nerved_; utricle ovate; style rather long; _seed orthotropous_, ovate or oval, obtuse, _with scarcely apiculate operculum_.--N. Y. and N. J., west to Mich. and Wisc.--Var. TRINERVIS, Austin, has larger, distinctly 3-nerved fronds, and an unequally cordate seed.

4. L. minor, L. _Fronds round- to elliptic-obovate_ (1--21/2'' in diameter), rather thick, _very obscurely 3-nerved; spathe sac-like_; utricle short-urn-shaped, tipped with a short style; seed oblong-obovate, _amphitropous, with prominent rounded operculum_.--Stagnant waters, throughout N. Am. (Eu.)

[*][*] _Ovules 2--7, anatropous; fronds very thick and spongy, flat above, very obscurely 5-nerved (11/2--3'' long)._

5. L. gibba, L. Fronds obovate-elliptic to nearly orbicular, almost hemispherical, soon separating; bract sac-like.--Mo. (?) to Ariz. and Calif.

3. WOLFFIA, Horkel.

Flowers central, bursting through the upper surface of the globular (or in some foreign ones flat) and loosely cellular frond, only 2; one consisting of a single stamen with a 1-celled 2-valved anther; the other of a globular ovary, tipped with a very short style and a depressed stigma. Ovule orthotropous, rather oblique in the cell. Utricle spherical. Albumen thin.--Fronds rootless, proliferous from a cleft or funnel-shaped opening at the base, the offspring soon detached; no rhaphides.--The simplest and smallest of flowering plants, from 1/4--{2/3}'' long (an African and Cuban species much larger), floating as little grains on the water. (Named for _John Fred. Wolff_, who wrote on Lemna in 1801.)

1. W. Columbiana, Karsten. Globose or globular, {1/3}--{2/3}'' long, very loosely cellular, light green all over, not dotted; stomata 1--6; the opening at the base circular and with a thin border.--Floating rather beneath the surface of stagnant waters, Conn. to N. J., west to Minn. and La.

2. W. Brasiliensis, Weddell. Oblong, smaller and more densely cellular, flattish and deep green with many stomata above, tumid and pale below, brown-dotted all over, anterior edge sharp, opening at base circular.--Growing with the last, but floating on the surface.

ORDER 125. ALISMACEAE. (WATER-PLANTAIN FAMILY.)

_Marsh herbs, with scape-like stems, sheathing leaves, and perfect or monoecious or dioecious flowers; perianth of 3 herbaceous persistent sepals and as many (often conspicuous) white deciduous petals, which are imbricate or involute in bud; stamens 6 or more, included; ovaries numerous, distinct, 1-celled and mostly 1-ovuled, becoming achenes in fruit_ (in our genera); _seeds erect; campylotropous._--Roots fibrous; leaves radical, petiolate and strongly nerved with transverse veinlets, the earlier sometimes without blade; flowers long-pedicellate, mostly verticillate, in a loose raceme or panicle, with lanceolate scarious bracts slightly connate at base.

1. Alisma. Flowers perfect, usually 6-androus. Carpels flattened, in one whorl.

2. Sagittaria. Flowers mostly unisexual. Stamens rarely few. Carpels flattened, in dense heads, winged.

3. Echinodorus. Flowers perfect. Stamens 6 or more. Carpels capitate, turgid and ribbed, often beaked.

1. ALISMA, L. WATER-PLANTAIN.

Flowers perfect. Petals involute in the bud. Stamens definite, mostly 6. Ovaries many in a simple circle on a flattened receptacle, forming flattened coriaceous achenes, which are dilated and 2--3-keeled on the back.--Roots fibrous. Leaves all from the root, several-ribbed, with connected veinlets. Scape with whorled panicled branches. Flowers small, white or pale rose-color. (The Greek name; of uncertain derivation.)

1. A. Plantago, L. Perennial by a stout proliferous corm; leaves long-petioled, ovate, oblong, or lanceolate or even linear, acute, mostly rounded or heart shaped at base, 3--9-nerved; panicle loose, compound, many-flowered (1--2 deg. long); carpels obliquely obovate, forming an obtusely triangular whorl in fruit.--Shallow water and ditches, across the continent. Very variable as to foliage, but the leaves usually more broadly cordate-ovate than in Old World forms (var. Americanum, _R. & S._); when growing under water thinner and narrowly lanceolate. (Eu., etc.)

2. SAGITTARIA, L. ARROW-HEAD.

Flowers monoecious, or often dioecious in n. 1 and 4, and polygamous in n. 7. Petals imbricated in the bud. Stamens indefinite, rarely few. Ovaries many, crowded in a spherical or somewhat triangular depressed head on a globular receptacle, in fruit forming flat membranaceous winged achenes.--Marsh or aquatic, mostly perennial, stoloniferous herbs, with milky juice and fibrous roots; the scapes sheathed at base by the bases of the long cellular petioles, of which the primary ones, and sometimes all, are flattened, nerved, and destitute of any proper blade (i.e. are phyllodia); when present the blade is arrow-shaped or lanceolate, nerved and with cross-veinlets as in Alisma. Flowers produced all summer, whorled in threes, with membranous bracts; the sterile above. (Name from _sagitta_, an arrow, from the prevalent form of the leaves.)

Sec. 1. SAGITTARIA proper. _Flowers monoecious, with the lower whorls pistillate, or dioecious; stamens few or numerous, covering the receptacle; sepals spreading or reflexed in fruit._

[*] _Filaments numerous, narrow, as long as or longer than the linear-oblong anthers; bracts 3, distinct; fruiting heads larger._

1. S. variabilis, Engelm. Scape (1/4--4 deg. high) angled, with one or more of the lower whorls fertile; leaves very various, almost always sagittate; bracts mostly pointed; pedicels of the fertile flowers at least half the length of the sterile ones; petals wholly white; filaments glabrous, nearly twice the length of the anthers; achenes obovate (about 1'' long), winged on both margins, with a long curved or usually horizontal beak 1/4--{1/3} its length. (S. sagittaefolia, _L._, var. variabilis, _M. Micheli._)--In water or wet places, very common; exceedingly variable in size and foliage, ordinarily with narrow halberd-shaped or sagittate leaves,--sometimes dioecious, with large, broad and obtuse leaves (var. OBTUSA), or monoecious, with large, broad and acute leaves (var. LATIFOLIA), or the narrow leaves with long and linear diverging lobes (var. ANGUSTIFOLIA), or with some leaves lanceolate or ovate-lanceolate, others more or less sagittate (var. DIVERSIFOLIA), etc. Root propagating by stolons tuberiferous at the extremity.--The European species has the fertile pedicels only {1/3} or 1/4 the length of the sterile; claws of the petals purple-tinged; filaments not longer than the anthers; and achenes almost orbicular, very broadly winged and with a short straight beak.

Var. pubescens, Engelm. Upper part of petiole and scape and especially the orbicular-ovate obtuse bracts and sepals pubescent or woolly; beak of fruit horizontal.--N. J. and Penn. to Ga.

Var. (?) gracilis, Engelm. Lobes of the sagittate leaves very narrowly linear (1/2--2'' wide); achene narrowly cuneate-obovate (2'' long), the beak long, stout, and strongly recurved, the sides usually strongly 1--3-crested. (S. cristata, _Engelm._?)--Mass. to western N. Y.; Iowa.

2. S. lancifolia, L. Scape 2--5 deg. high, with several of the lower whorls fertile; leaves lanceolate or lance-oblong, rarely linear, all with a tapering base, thick or coriaceous (6--18' long and on a long and stout petiole, never sagittate), the nerves mostly arising from the very thick midrib; bracts ovate, acute or acuminate; pedicels slender, the fertile scarcely shorter than the sterile ones; filaments pubescent; achenes falcate, winged on the back, pointed with an incurved beak.--Swamps, Md. to Ky., Mo., and southward. (W. Ind.)

[*][*] _Filaments very short, with enlarged mostly glandular base; anthers ovate or short-oblong; fruiting heads small; bracts more or less connate; leaves very rarely sagittate._

3. S. heterophylla, Pursh. Scape weak (3'--2 deg. high), at length procumbent; leaves lanceolate or lance-oval, entire, or with one or two narrow basal sagittate appendages; _bracts roundish, obtuse_; flowers of the lowest whorl fertile and _almost sessile_; the sterile on long pedicels; filaments glandular-pubescent; _achenes narrowly obovate with a long erect beak_.--N. Eng to Fla., west to Minn. and Mo. Varies as to foliage, the leaves being broad (var. ELLIPTICA, Engelm.), or rigid and narrowly lanceolate with stout petioles (var. RIGIDA, Engelm.), or nearly linear (var. ANGUSTIFOLIA, Engelm.)

4. S. graminea, Michx. Scape 3'--2 deg. high; _phyllodia flat_, mostly _broadly linear, acuminate_; leaves ovate-lanceolate to linear, on long slender petioles, sometimes reduced to the petiole merely; bracts rather obtuse; whorls of flowers often few, all staminate or the lower fertile; _pedicels_ slender, _spreading_, nearly equal; _filaments 15--20, glandular-pubescent; achene small_ (1/2'' long), narrowly obovate, almost beakless, _winged on the back, flat and scarcely costate on the sides_.--N. Eng. to Minn., south to the Gulf; very variable.

5. S. teres, Watson. _Phyllodia terete, very acutely attenuate_ upward, 3--12' long, very rarely bearing a narrow blade; scape 1/2--11/2 deg. high; bracts connate at base; _pedicels_ in 1--3 whorls, all very _slender and spreading_, 1 or 2 fruiting, 1/2--1' long; filaments 12, dilated, pubescent; _achene_ obovate, 1'' _long, with an erect beak_, the margins and sides _crenately several-crested_.--In shallow water, S. New Eng. to N. J. (Hyannis, Mass., _Deane_; Wading River, L. I., _Miller_; barrens of N. J., _Torrey_.) Phyllodia usually very strongly nodose. (Addendum)--Sagittaria teres has been collected also at Brewster, Mass. (_Farlow_).

6. S. natans, Michx., var. lorata, Chapm. Usually dwarf; _leaves linear, strap-shaped, obtuse or acutish_, 1--6' long, equalling or shorter than the scape, very rarely with a narrow blade; pedicels in 1--3 whorls, only 1 or 2 fruiting, _stouter and recurved_; bracts connate or spathe-like; _filaments 6--8, glabrous; achene_ obovate, _short-beaked, 1'' long_, the margins and sides _crenately crested_. (S. pusilla, _Pursh._)--In mud or shallow water, near the coast; N. Y. to Fla.

Var. (?) gracillima, Watson. Scape and the almost or wholly bladeless leaves very slender and greatly elongated (2--4 deg. long, 1'' wide); pedicels all elongated, in usually distant whorls, the lower pistillate, slender and spreading; fruit unknown. (S. natans, _Engelm._ in Torr. Bull. ix. 4.)--In deep water of streams in E. Mass. (_Hitchings, Boott, C. E. Faxon_, etc.) Wholly submerged, only 1 or 2 flowers appearing at a time, floating on the surface. The fruit, maturing under water, has not yet been collected.

Sec. 2. LOPHIOCARPUS. _Fertile flowers perfect; stamens 9--15, at the base of the receptacle; sepals erect and embracing the fruit._

7. S. calycina, Engelm. Scape weak (3--9' high), at length mostly procumbent; usually only the lowest whorl fertile, with pedicels as long as those of the sterile flowers, recurved in fruit; bracts orbicular, obtuse or rarely pointed; filaments slightly rough, as long as the anthers; achenes obovate with a short horizontal style; leaves broadly halberd-shaped, obtuse or acutish, with wide spreading lobes, often wider than long, or lanceolate or sometimes reduced to linear phyllodia.--Maine to Del., west to Wisc., Mo., and Tex. Quite variable, several forms being enumerated, as var. SPONGIOSA, with spongy texture and bladeless submerged leaves, eastward; and westward, var. FLUITANS, with lance-linear floating leaves.

3. ECHINODORUS, Richard.

Flowers perfect. Petals imbricated in the bud. Stamens 6--21 or more. Ovaries several or many, imbricated in a head, forming thick and ribbed achenes in fruit, often beaked with a projecting persistent style.--Mostly annuals, with the habit of Sagittaria, the naked stems sparingly branched or simple, and the flowers on rather short pedicels, in whorls of 3--6 or more. Fl. summer and autumn. (Name from [Greek: e)chino/des], _prickly_, or from [Greek: e)chi~nos], and [Greek: doro/s] _a leathern bottle_, applied to the ovary, which is in most species armed with the persistent style, so as to form a sort of prickly head of fruit.)

1. E. parvulus, Engelm. Scapes 1--3' high; shoots often creeping and proliferous; _leaves lanceolate or spatulate, acute_ (1/2--11/2' long, including the petiole); umbel single, 2--8-flowered; pedicels reflexed in fruit; flower 3'' broad; _stamens 9; styles much shorter than the ovary; achenes beakless_, obtusely few-ribbed.--In mud, Mass. to Mich. and E. Minn., south to Fla. and Tex. (S. Am.)

2. E. rostratus, Engelm. _Scape erect_, 3'--2 deg. high, longer than the leaves; _leaves broadly ovate, cordate or truncate at base, obtuse_ (the blade 1--3' long); umbel proliferous, in a branched panicle; flower 5'' broad; _stamens 12; styles longer than the ovary; achenes beaked_, acutely many-ribbed.--Swamps and ditches, Ill. to Fla., Mo., and Tex.--A low form (var. LANCEOLATUS, Engelm.) has the leaves lanceolate with an acute base. Ill., Mo.

3. E. radicans, Engelm. _Stems or scape prostrate, creeping_ (2--4 deg. long), proliferous, bearing many whorls of flowers; leaves somewhat truncately broadly heart-shaped, obtuse (2--8' broad), long-petioled; flowers 6--9'' broad; _stamens about 21; styles shorter than the ovary; achenes short-beaked_, the keeled back denticulate.--Swamps, Ill. to N. C. and Fla., west to Mo. and Tex.

ORDER 126. NAIADACEAE. (PONDWEED FAMILY.)

_Marsh or mostly immersed aquatic herbs, with stems jointed and leafy or_ (in Triglochin) _naked and scape-like, leaves sheathing at base or stipulate, and flowers perfect or unisexual, often spathaceous, with perianth of 4 or 6 herbaceous distinct valvate segments, or membranous and tubular or cup-shaped, or none._ Stamens 1, 2, 4 or 6, with extrorse anthers. Ovaries 1--6, distinct or more or less coherent, 1-celled, usually 1-ovuled, in fruit follicular or capsular or an indehiscent berry or utricle.

SUBORDER I. Juncagineae. Marsh plants, with terete bladeless leaves; flowers perfect, spicate or racemose, with herbaceous 6- (rarely 3-) lobed perianth; carpels 3 or 6, more or less united, separating at maturity. Seeds anatropous; embryo straight.

1. Triglochin. Ovaries 3--6, united until maturity. Leaves radical. Flowers bractless, in a spike-like raceme terminating a jointless scape.

2. Scheuchzeria. Ovaries 3, nearly distinct, at length divergent. Flowers bracteate in a loose raceme upon a leafy stem.

SUBORDER II. Naiadeae. Immersed aquatics, with flat leaves; ovaries solitary or distinct, 1-ovuled.

[+] Flowers perfect, spiked or clustered; anthers 4 or 2, sessile; leaves alternate.

3. Potamogeton. Spike peduncled. Sepals 4, herbaceous. Anthers 4. Ovaries 4, sessile.

4. Ruppia. Flowers on an enclosed spadix, at length long-exserted, without perianth. Anther-cells 4, distinct. Ovaries 4, becoming stipitate.

[+][+] Flowers monoecious or dioecious, axillary, naked, monandrous; leaves opposite (alternate in n. 6).

5. Zannichellia. Monoecious. Pistils (2--5) from a cup-shaped involucre or sheath.

6. Zostera. Pistils and stamens alternate in 2 vertical rows on the inner side of a leaf-like enclosed spadix. Stigmas 2, linear. Stem creeping.

7. Naias. Dioecious; pistil solitary, naked. Stamen enclosed in a membranous spathe. Stems floating, with opposite or ternate leaves.

1. TRIGLOCHIN, L. ARROW-GRASS.

Sepals and petals nearly alike (greenish), ovate, concave, deciduous. Stamens 3--6; anthers oval, on very short filaments. Pistils united into a 3--6-celled compound ovary; stigmas sessile; ovules solitary. Capsule splitting when ripe into 3--6 carpels, which separate from a persistent central axis.--Perennials, with rush-like, fleshy leaves, below sheathing the base of the wand-like naked and jointless scape. Flowers small, in a spiked raceme, bractless. (Name composed of [Greek: trei s], _three_, and [Greek: glochi/n], _point_, from the three points of the ripe fruit in n. 1 when dehiscent.)

[*] _Fruit of 3 carpels._

1. T. palustris, L. Scape (6--18' high) and leaves slender; _sepals and stamens 6; fruit linear-club-shaped; carpels_ when ripe separating from below upward, leaving a triangular axis, _awl-pointed at base_.--Marshes, western N. Y. to Ill., Minn., and westward. Aug. (Eu., Asia, etc.)

2. T. striata, Ruiz & Pav. Scape (6--12' high) and leaves slender; flowers very small; _sepals and stamens 3; fruit globose-triangular_, or when dry 3-lobed. (T. triandra, _Michx._)--Sea-shore, Md. to Fla. (S. Am., etc.)

[*][*] _Fruit of 6 carpels (rarely 5)._

3. T. maritima, L. Scape (1--3 deg. high) and leaves thickish, fleshy; fruit ovate or oblong, acutish; carpels rounded at base and slightly grooved on the back, the edges acute.--Salt-marshes along the coast, Lab. to N. J., and in saline places in the interior across the continent. (Eu., Asia, etc.)

2. SCHEUCHZERIA, L.

Sepals and petals oblong, spreading, nearly alike (greenish-yellow), but the latter narrower, persistent. Stamens 6; anthers linear. Ovaries 3, globular, slightly united at base, 2--3 ovuled, bearing flat sessile stigmas, in fruit forming 3 diverging and inflated 1--2 seeded pods, opening along the inside.--A low bog-herb, with a creeping jointed rootstock, tapering into the ascending simple stem, which is zigzag, partly sheathed by the bases of the grass-like conduplicate leaves, and terminated by a loose raceme of a few flowers, with sheathing bracts; leaves tubular at the apex. (Named for _John_ and _John Jacob Scheuchzer_, distinguished Swiss botanists early in the 18th century.)

1. S. palustris, L.--Peat-bogs, N. Brunswick to N. J., westward across the continent. June. (Eu., Asia.)

3. POTAMOGETON, Tourn. PONDWEED.

Flowers perfect. Sepals 4, rounded, valvate in the bud. Stamens 4, opposite the sepals; anthers nearly sessile, 2-celled. Ovaries 4 (rarely only one), with an ascending campylotropous ovule; stigma sessile or on a short style. Fruit drupe-like when fresh, more or less compressed; endocarp (_nutlet_) crustaceous. Embryo hooked, annular, or cochleate, the radicular end pointing downward.--Herbs of fresh, or one in brackish, ponds and streams, with jointed mostly rooting stems, and 2-ranked leaves, which are usually alternate or imperfectly opposite; the submersed ones pellucid, the floating ones often dilated and of a firmer texture. Stipules membranous, more or less united and sheathing. Spikes sheathed by the stipules in the bud, mostly raised on a peduncle to the surface of the water. (An ancient name, composed of [Greek: potamo/s], _a river_, and [Greek: gei/ton], _a neighbor_, from the place of growth.)--By _fruit_, the full-grown fresh or macerated fruit is intended; by _nutlet_, that with the fleshy outer portion or epicarp removed. All except n. 19 flower in summer; the month mentioned indicates the time of ripening of the fruit.

Sec. 1. _Leaves of two sorts; floating ones more or less coriaceous, with a dilated petioled blade, different in form from the thinner submersed ones._

[*] _Submersed leaves reduced to narrowly grass-like or filiform sessile phyllodia._

[+] _Stems rather stout; stipules free; spikes all emersed, cylindrical and densely fruited; fruits fleshy and turgid, obliquely obovate._

1. P. natans, L. _Stem simple or sparingly branched_; floating leaves all long-petioled, elliptical or ovate, somewhat cordate at base, obtuse but with a blunt point, 21--29-nerved; upper submersed leaves lanceolate, early perishing, the lower (later in the season) very slender (3--7' long, barely 1'' wide); upper _stipules very long, acute; peduncle about the thickness of the stem_; spikes 1--2' long; sides of the turgid _nutlet with a small deep impression in the middle_; embryo coiled into an incomplete elliptical ring.--Ponds and ditches, N. Scotia to Va., westward across the continent. In deeper or flowing water the plant becomes more slender and often wholly submersed (var. PROLIXUS, _Koch_).--Aug., Sept. (Eu., Asia.)

2. P. Oakesianus, Robbins. Stem more slender, _much branched_; floating leaves smaller (1--11/2' long), ovate- or oblong-elliptical, obtuse, fewer-(17--23-) nerved; lowest submersed ones almost capillary (only 1/4--1/2'' wide), continuing through the flowering season; spikes shorter (3/4--1' long), on _peduncles much thicker than the stem_; fruit smaller and more acute; _sides of the turgid nutlet not at all impressed_; curvature of the embryo nearly circular, its apex directed to a point above its base.--Ponds, and especially pools and stagnant ditches, Mass. to N. J.; also Anticosti. Aug.

3. P. Pennsylvanicus, Cham. _Stems compressed_, often simple from the creeping rootstocks; floating leaves chiefly opposite (1--31/2' long), 11--17-nerved, oblong, tapering into a _short petiole_, the lower gradually narrowing and passing into the submersed ones, which are very numerous and approximate, 2-ranked, linear (2--5' long, and 1--21/2'' wide), 5--7-nerved, the lateral nerves slender and nearly marginal, the space within the inner nerves _coarsely cellular-reticulated; stipules very obtuse_; spikes numerous, about the length of the thickened peduncle; _fruit round-obovate_, flattish, 3-keeled when dry; _nutlet distinctly impressed on the sides_; curvature of the embryo transversely oval. (P. Claytonii, _Tuckerm._)--Still or flowing water, N. Brunswick to S. C., west to N. Ind. and Minn. July, Aug.

[+][+] _Like the preceding section, but all the parts small, slender and delicate, only the fertile plants producing floating leaves; spikes very small and few-flowered; propagated by autumn buds._

4. P. Vaseyi, Robbins. Very delicate; stem almost capillary; _floating leaves obovate_ (3--5'' long) and about the length of their filiform petioles, with 5 nerves deeply impressed beneath, cross-veins distinct; submersed leaves filiform-linear, very attenuate (1--2' long, {1/8}--1/4'' wide) and acute; _stipules_ not adnate, scarious, _long_, acute; spikes all emersed, few, interrupted-oblong, 3--5-flowered, on a thickish peduncle; fruit oblique, round-obovate ({2/3}'' long), compressed, slightly sharp-margined, tipped with a distinct recurved style, the sides impressed and face acute; upper portion of the embryo circularly incurved, its apex transverse to the fruit.--Canada and N. Eng.; also Ill. The fruiting form, with floating leaves, rare; the submerged form apparently much more abundant.

5. P. lateralis, Morong. Stem filiform, branching; _floating leaves elliptical_ (4--6'' long by 2'' wide), with 5--7 nerves deeply impressed beneath, tapering at base into a somewhat dilated petiole shorter than the blade; _submersed leaves linear_, acute (1--3' long by 1/4--1/2'' wide), 1--3-nerved, the mid-nerve with fine veins or cellular reticulations on each side, bi-glandular at base; _stipules short; peduncles with a very peculiar lateral appearance_, widely spreading at maturity, sometimes even recurved, often thicker than the stem; spikes often interrupted (2--4-flowered); fruit obliquely obovate (hardly 1'' long), the back much curved, with two fine grooves upon it; embryo oval in its curve, the apex nearly touching the base.--Mass. and Mich.; rare. Undeveloped specimens resemble P. pusillus.

[+][+][+] _Stems slender or filiform, much branched; floating leaves sometimes wanting; stipules adnate to the base of the leaf; spikes of two kinds, one emersed, cylindrical and many-flowered, on a club-shaped peduncle, the other submersed, globular and few-flowered; fruit flat, cochleate, with thin or scarcely any flesh and a thin nutlet; embryo spiral._

6. P. Spirillus, Tuckerm. Floating leaves oval to lance-oblong and lanceolate (the largest 10'' long, 4'' wide), usually obtuse, about equalling the _rather dilated petioles_, with 5--many nerves beneath deeply impressed; upper submersed leaves either with or without a lance-oblong or broad-linear proper blade; the numerous lower ones narrow-linear, tapering toward the obtuse apex (3/4--11/2' long, 1/4--{2/3}'' wide); stipules early lacerate; _submersed flowers usually solitary on very short erect peduncles; fruit_ with the back either _winged and with 4--5 distinct teeth or wingless and entire; embryo coiled 13/4 turns_.--Rivers, and even far up small streams, N. Eng. to Va., west to Mich. and Mo. June--Aug.--Stem less slender than in the next.

7. P. hybridus, Michx. Floating leaves oval to lance-oblong (the largest 10'' long, 6'' wide), often acute, longer than the _filiform petioles_, with about 5--7 nerves beneath deeply impressed; submersed leaves very numerous, almost setaceous (1--3' long, very rarely 1/2'' wide); stipules obtuse; emersed spikes 4--7'' long; _submersed_ spikes 1--4-flowered, their _peduncles_ (of their own length) _frequently recurved; fruit minute, about 8-toothed on the margin; embryo coiled 11/2 turns_.--Shallow stagnant waters, N. Brunswick to Fla., west to Mich., Mo., and N. Mex. June--Aug.

[*][*] _Submersed leaves lanceolate, rarely oval or linear, membranaceous; spikes dense, many-flowered, on stout peduncles._

8. P. rufescens, Schrad. Stem simple; floating leaves (often wanting) 2--5' long, rather thin, _wedge-oblanceolate, narrowed into a short petiole_, 11--17-nerved; _submersed leaves almost sessile_, lanceolate and lance-oblong, smooth on the margin, fewer-nerved; stipules broad, hyaline, obtuse, upper ones acuminate; spike 1--2' long, often somewhat compound; fruit obovate, lenticular, pitted when immature, with an acute margin and pointed with the rather long style; embryo incompletely annular.--In streams or ponds, N. Brunswick to N. J., west to Minn. and Tex. Aug., Sept. (Eu.)

9. P. fluitans, Roth. Stem often branching below; _floating leaves thinnish, lance-oblong or long-elliptical_, often acute, _long-petioled_, 17--23-nerved; _submersed leaves very long_ (3--12', by 2--12'' wide), _lanceolate and lance-linear_, 7--15-nerved, coarsely reticulated; peduncles somewhat thickened upward; fruit obliquely obovate, obscurely 3-keeled when fresh, and distinctly so when dry, the middle one winged above and sometimes with 3--5 shallow indentations; the rounded slightly curved face surmounted by the short style; nutlet with the sides scarcely impressed; upper part of the embryo circularly in-curved. (P. lonchites, _Tuckerm._)--In streams or rarely in ponds, N. Brunswick to N. J., west to Minn. and Iowa. Aug., Sept. (Eu.)

10. P. pulcher, Tuckerm. Stem simple, black-spotted; _leaves of three kinds_; floating ones becoming very large (41/2 by 31/2'), _roundish-ovate and cordate or ovate-oblong_, 25--37-nerved, _all alternate; upper submersed ones (3--5) usually lanceolate_, acute at base and very long-acuminate, 10--15-nerved, very thin, cellular each side of the midrib, undulate, short-petioled; _lowest_ (2--4 near the base of the stem) _thicker, plane, oval or oblong_ with a rounded base, or spatulate-oblong, on longer petioles; stipules rather short and obtuse; peduncles thicker than the stem; fruit with a rounded back and angular face, pointed, distinctly 3-keeled when fresh, sharply so when dry; nutlet with two deep dorsal furrows, and a sinus below the angle in front; sides flat; embryo circularly much incurved above.--Ponds, Vt. to Ga. and Mo. July, Aug.

11. P. amplifolius, Tuckerm. Stems simple, of very variable length; _floating leaves_ (sometimes wanting) large, _oblong or lance-ovate_, sometimes slightly cordate at base, abruptly acutish, 30--50-nerved, on _rather long petioles_; submersed leaves often very large (reaching 7' by 2'), lanceolate or oval, acute at each end, _usually much recurved, undulate_, mostly on short petioles; _stipules very long and tapering to a point_, soon becoming loose; peduncles thickened upward, in deep water much elongated; fruit very large (over 2'' long), rather obliquely obovate, 3-keeled, with a broad stout beak; nutlet slightly impressed on the sides; upper part of the embryo curved into a ring.--Ponds and rivers, N. Eng. to N. J., west to Minn. and Kan. Aug., Sept.

12. P. Illinoensis, Morong. _Stem stout, branching_ towards the summit; floating leaves opposite, oval or ovate (2--5' long by 11/2--2' broad), 19--25-nerved, rounded or subcordate at base, with a short blunt point at apex, on short petioles, _submersed leaves rather few, oblong-elliptical_, acute at each end, _usually ample_ (largest 8' by 11/2'); _stipules coarse, obtuse, strongly bicarinate_ (2' long); peduncles often clustered at the summit (2--4' long), thickening upward; _fruit roundish-obovate_ (13/4--2'' long), 3-keeled on the back, middle keel prominent; nutlet flattened and slightly impressed on the sides, obtuse or pointed at base; apex of embryo directed transversely inward.--Streams and ditches, western N. Y. to Ill., Iowa, and Minn. Very near the last.

13. P. heterophyllus, Schreb. _Stem slender, very branching_ below; floating leaves mostly thin, variable, but with a short blunt point, 9--15-nerved, usually 1--2' long and 6--9'' wide; submersed ones usually lanceolate or linear-lanceolate, acuminate or cuspidate, narrowed toward the base, about 7-nerved on the stem and 3-nerved on the branches; upper ones petioled, lower sessile; _stipules obtuse_, loose; peduncles somewhat thickened upward; fruit small, roundish, compressed, scarcely keeled; embryo annular above. (P. gramineus, _Fries_.)--Still or flowing water, common. Varies exceedingly in its submersed leaves, peduncles, etc.; the var. GRAMINIFOLIUS (Fries), growing in rapid streams, with stems much elongated and less branched, and the flaccid submersed leaves 2--7' long by 2--10'' wide.

Var. (?) myriophyllus, Robbins. Sending up from running rootstocks many short repeatedly dichotomous and densely leafy stems; fertile stems very slender; floating leaves small, delicate, lance-oblong, on long filiform petioles; submersed stem-leaves larger, early perishing; those of the branches (deep-green) linear-oblanceolate, very small (3/4--1' long), acute, sometimes minutely serrulate; spike slender, loosely-flowered, much shorter than the thickened peduncle.--Apponaug Pond, R. I., without fruit.

13^a. P. Zizii, Mert. & Koch. Resembling P. lucens, but smaller, much branched at base; _upper leaves coriaceous or subcoriaceous, long-petioled_ and _sometimes emersed_, the others subsessile, all usually numerous, undulate and _shining_; peduncle elongated. (P. lucens, var. minor, _Nolte_. Also P. gramineus, var. (?) spathulaeformis, _Robbins_; P. spathaeformis, _Tuckerm._; "P. varians, _Morong_.")--N. Eng to Fla., and westward. Connecting with the next section. (Eu.)

Sec. 2. _Leaves all submersed and similar, mostly sessile, membranaceous and dilated, lanceolate, oblong, or oval; stipules obtuse, becoming loose._

14. P. lucens, L. Stem thick, branching, sometimes very large; _leaves more or less petioled_, oval or lanceolate, _mucronate_, often rough serrulate, _frequently shining_; peduncles often elongated; _fruit_ roundish and compressed, _with obtuse margins, slightly keeled_; embryo circularly incurved above.--Ponds, N. Eng. to Fla., west to the Pacific. Aug., Sept. (Eu.)

Var. (?) Connecticutensis, Robbins. Stem flexuous; _leaves_ all submersed, nearly sessile, lanceolate, _acuminate, crisped, not shining nor serrulate; fruit larger, distinctly keeled_; nutlet thick and hard.--Lake Saltonstall, East Haven, Conn.

15. P. praelongus, Wulf. Stem very long, branching, flexuous; _leaves_ lance-oblong or lanceolate (sometimes 7' long), _half-clasping, obtuse with a boat-shaped cavity_ at the extremity, thence splitting on pressure; stipules scarious, very obtuse; spikes rather loose-flowered; _peduncles very long_ (sometimes reaching 20'); _fruit_ obliquely obovate, compressed, _sharply keeled_ when dry; style terminating the nearly straight face; curve of the embryo oval and longitudinal.--Ponds and large rivers, N. Scotia to Mass., west to Minn. and Iowa. Sept., Oct.--Stem white; foliage bright green. (Eu.)

16. P. perfoliatus, L. Stem branching; _leaves orbicular, ovate or lanceolate from a cordate-clasping base_, usually obtuse and often minutely serrulate; peduncles short, cylindrical; _fruit_ irregularly obovate, _obtusely margined_; embryo incurved in an oval.--Ponds and slow streams, common. N. Scotia to Fla., west to Minn. and Iowa. Sept., Oct. (Eu.)

Var. lanceolatus, Robbins. Larger; _leaves long-lanceolate_ from a cordate clasping base and _acuminate_, wavy, 3--41/2' long; _peduncles thickened upward_.--Same range as the species, and extending west to the Pacific.

17. P. crispus, L. _Stem compressed; leaves linear-oblong_, half-clasping, obtuse, _serrulate, crisped-wavy, 3-nerved; fruit long-beaked_; upper portion of the embryo incurved in a large circle.--Flowing and stagnant waters, Mass. to N. J. and Va., west to western N. Y. June, July. (Eu.)

18. P. Mysticus, Morong. _Stem very slender_ and irregularly branching, nearly filiform (1--3 deg. high); _leaves oblong-linear_ (1/2--11/2' long by 2--3'' wide), 5--7-nerved, _finely undulate and entire, obtuse or bluntly pointed, abruptly narrowing at base, sessile or partly clasping_; spikes few, capitate (4--6-flowered). on erect peduncles (1--2' long); fruit (immature) obovate, small (hardly 3/4'' long), _obscurely 3-keeled on the back_, a little beaked by the slender recurved style.--Mystic Pond, Medford, Mass.

Sec. 3. _Leaves all submersed and similar, mostly membranaceous and sessile, linear or setaceous._

[*] _Stipules free from the sheathing base of the leaf._

19. P. zosteraefolius, Schum. _Stem branching, wing-fattened; leaves_ linear and grass-like (commonly 4' by 11/2''), _abruptly pointed, with many fine and 3 larger nerves_; stipules (seen young) oblong, very obtuse; _spikes cylindrical_, 12--15-flowered, _not half as long as the peduncle_; fruit obliquely obovate, somewhat keeled and with slight teeth on the back, the sides not impressed, the face arching and terminated by the short style; _summit of the large embryo lying transverse to the fruit_. (P. compressus, _Fries_; not _L._?)--Still and slow-flowing waters, N. Eng. to N. J., Iowa, and Minn. Aug., Sept. (Eu.)

20. P. Hillii, Morong. Stem slender, _widely branching, flattish_; leaves linear, _acute_ (1--21/2' long by 1/2--11/4'' wide), _3-nerved_, the lateral nerves delicate and near the margin; stipules whitish, striate, obtuse (3--5'' long); _spikes capitate_ (3--6-fruited), _on short spreading or recurved peduncles_; fruit as in the last.--Mich. and western N. Y.

21. P. obtusifolius, Mertens & Koch. _Stem flattened, very branching; leaves_ linear, tapering toward the base, obtuse and mucronate or very acute, _3- (rarely 5-) nerved; stipules elongated_, very obtuse; _spike ovate, continuous_, 5--8-flowered, _about the length of the peduncle_; fruit oval, apiculate with the style, not keeled when fresh, _upper portion of embryo_ coiled inward and _lying transverse to the fruit_.--Slow streams and ponds, Canada and N. Eng. to western N. Y. and Mich. Sept., Oct. (Eu.)

22. P. pauciflorus, Pursh. _Stem filiform, flattish and very branching; leaves narrowly linear_ (1--2' long and seldom 1/2'' wide), acute, _obscurely 3-nerved; stipules obtuse; spikes_ capitate, 1--4- _(usually 2-) flowered_, on short club-shaped peduncles; _fruit roundish-lenticular_; the _back_ more or less _crested_; upper portion of the embryo incurved in a circle.--Still or stagnant waters, N. Brunswick to Ga., Iowa, Minn., and westward.

Var. Niagarensis, Gray. Stem often longer (1--3 deg.); leaves larger (11/2--31/2' long by 1'' wide or less), 3--5-nerved at base, very acute and mucronate, narrowed to the subpetiolate base. (P. Niagarensis, _Tuckerm_.)--Running water, Great Lakes to S. C.; also in Cal.

23. P. pusillus, L. _Stem slender_, flattish or nearly cylindrical, often very branching; _leaves narrow- or setaceous-linear_, acuminate, _acute or subacute, 1--3-nerved_, furnished with _translucent glands_ on each side at the base; stipules at first obtuse; spikes interrupted or capitate, 2--8-flowered, on rather long peduncles; _fruit_ obliquely elliptical, _scarcely keeled; apex of embryo_ incurved and _directed obliquely downward_.--Pools and ditches, N. Scotia to N. J., west to Minn. and Mo., and westward.--Leaves sometimes almost setaceous (var. tenuissimus, _Koch_).

Var. polyphyllus, Morong. Dwarf form (3--5' high), divaricately branching from the base, very leafy throughout; leaves very obtuse, not cuspidate, 3-nerved; non-flowering but abundantly provided with propagating buds which are formed on the thickened and hardened ends of the branches and closely invested by imbricated leaves.--In a shallow pool, S. Natick, Mass.

24. P. mucronatus, Schrad. Resembling P. pusillus, but stem less branching; _leaves broader_ (almost 1'' wide), _often 5-nerved; spikes interrupted_. (P. pusillus, var. major, _Fries_.)--N. Brunswick to western N. Y., Mich., and Minn. July. (Eu.)

25. P. gemmiparus, Robbins. Stem filiform, branching, terete, varying greatly in height; _leaves hair-like_, sometimes not as broad as the stem, often with no apparent midrib, _tapering to the finest point_ (1--3' long), bi-glandular at base; stipules 1/2--1' long; spikes few (3--6-flowered), _interrupted_, on long filiform peduncles; _propagating buds very numerous_; fruit like that of P. pusillus, very rare. (P. pusillus, var.? gemmiparus, _Robbins_.)--Slow-moving streams and still water, Mass. Aug., Sept.

26. P. Tuckermani, Robbins. _Very slender and delicate_ from a creeping rootstock, of a fine light green; stem filiform with several short and repeatedly dichotomous leaf-bearing branches; _leaves_ thin and flat, but _setaceous and tapering to near the fineness of a hair_ (1--4' long and {1/3}'' extreme width), obscurely 1--3-nerved, with a few coarse reticulations; stipules rather persistent below, {1/3}' long, obtuse; _peduncle solitary, very long_, rather thickened upward; _spike 4--8-flowered, in fruit continuous, oblong; fruit thick-lenticular_, obscurely 3-keeled; _nutlet slightly impressed on the sides; shell thick and hard_; embryo nearly annular.--Cold ponds, White Mountains of N. H., N. Y., and N. J.

[*][*] _Stipules united with the sheathing base of the leaf._

27. P. pectinatus, L. _Stem filiform_, repeatedly dichotomous; _leaves very narrowly linear_, attenuate to the apex, 1-nerved with a few transverse veins; _spikes interrupted_, on long filiform peduncles; fruit obliquely broad-obovate, compressed, _bluntly keeled_; shell of nutlet very thick; _embryo spirally incurved_.--N. Brunswick to Fla., westward across the continent. Aug.--Oct. (Eu.)

28. P. marinus, L. Resembling narrow-leaved forms of the last species, _low and very leafy_; peduncles much elongated; _fruit much smaller_ (1'' long) and thinner, round-obovate, _not keeled_ upon the rounded back, tipped with the broad sessile stigma; _embryo annular_.--Western N. Y., Ill., Mich., and southward. Probably the range of this species is much more extensive than indicated, as it has been confounded with P. pectinatus.

29. P. Robbinsii, Oakes. _Stem_ ascending from a creeping base, _rigid_, very branching, _invested by the bases of the leaves and stipules; leaves crowded in two ranks, recurved-spreading_, narrow-lanceolate or linear (3--5' long and 2--3'' wide), acuminate, _ciliate-serrulate_ with translucent teeth, many-nerved; stipules obtuse when young, their nerves soon becoming bristles; _spikes numerous, loosely few-flowered_, on short peduncles; fruit oblong-obovate (2'' long), _keeled with a broadish wing_, acutely beaked; embryo stout, ovally annular.--In ponds and slow streams, N. Brunswick to N. J., the N. shore of L. Superior, and far westward.

4. RUPPIA, L. DITCH-GRASS.

Flowers perfect, 2 or more approximated on a slender spadix, which is at first enclosed in the sheathing spathe-like base of a leaf, entirely destitute of floral envelopes, consisting of 2 sessile stamens, each with 2 large and separate anther-cells, and 4 small sessile ovaries, with solitary campylotropous suspended ovules; stigma sessile, depressed. Fruit small obliquely ovate pointed drupes, each raised on a slender stalk which appears after flowering; the spadix itself also then raised on an elongated thread-form peduncle. Embryo ovoid, with a short and pointed plumule from the upper end, by the side of the short cotyledon.--Marine herbs, growing under water, with long and thread-like forking stems, and slender almost capillary alternate leaves, sheathing at the base. Flowers rising to the surface at the time of expansion. (Dedicated to _H. B. Ruppius_, a German botanical author of the early part of the 18th century.)

1. R. maritima, L. Leaves linear-capillary; nut ovate, obliquely erect, 11/2'' long; fruiting peduncles capillary (3--6' long); stipes 1--12'' long.--Shallow bays, along the entire coast; also occasionally in saline places in the interior. (Eu., Asia, etc.)

5. ZANNICHELLIA, Micheli. HORNED PONDWEED.

Flowers monoecious, sessile, naked, usually both kinds from the same axil; the sterile consisting of a single stamen, with a slender filament bearing a 2--4-celled anther; the fertile of 2--5 (usually 4) sessile pistils in the same cup-shaped involucre, forming obliquely oblong nutlets in fruit, beaked with a short style, which is tipped by an obliquely disk-shaped or somewhat 2-lobed stigma. Seed orthotropous, suspended, straight. Cotyledon taper, bent and coiled.--Slender branching herbs, growing under water, with mostly opposite long and linear thread-form entire leaves, and sheathing membranous stipules. (Named in honor of _Zannichelli_, a Venetian botanist.)

1. Z. palustris, L. Style at least half as long as the fruit, which is flattish, somewhat incurved, even, or occasionally more or less toothed on the back (not wing-margined in our plant), nearly sessile; or, in var. PEDUNCULATA, both the cluster and the separate fruits evidently peduncled.--Ponds and slow streams, throughout N. America, but not common. July. (Eu., Asia.)

6. ZOSTERA, L. GRASS-WRACK. EEL-GRASS.

Flowers monoecious; the two kinds naked and sessile and alternately arranged in two rows on the midrib of one side of a linear leaf-like spadix, which is hidden in a long and sheath-like base of a leaf (spathe); the sterile flowers consisting of single ovate or oval 1-celled sessile anthers, as large as the ovaries, and containing a tuft of threads in place of ordinary pollen; the fertile of single ovate-oblong ovaries attached near their apex, tapering upward into an awl-shaped style, and containing a pendulous orthotropous ovule; stigmas 2, long and bristle-form, deciduous. Utricle bursting irregularly, enclosing an oblong longitudinally ribbed seed (or nutlet). Embryo short and thick (proper cotyledon almost obsolete), with an open chink or cleft its whole length, from which protrudes a doubly curved slender plumule.--Grass-like marine herbs, growing wholly under water, from a jointed creeping stem or rootstock, sheathed by the bases of the very long and linear, obtuse, entire, grass-like, ribbon-shaped leaves (whence the name, from [Greek: zoste/r], _a band_).

1. Z. marina, L. Leaves obscurely 3--5-nerved.--Common in shoal water of bays along the coast, from Newf. to Fla. (Eu.)

7. NAIAS, L. NAIAD.

Flowers dioecious or monoecious, axillary, solitary and sessile; the sterile consisting of a single stamen enclosed in a little membranous spathe; anther at first nearly sessile, the filament at length elongated. Fertile flowers consisting of a single ovary tapering into a short style; stigmas 2--4, awl-shaped; ovule erect, anatropous. Fruit a little seed-like nutlet, enclosed in a loose and separable membranous epicarp. Embryo straight, the radicular end downward.--Slender branching herbs, growing under water, with opposite and linear leaves, somewhat crowded into whorls, spinulose-toothed, sessile and dilated at base. Flowers very small, solitary, but often clustered with the branch-leaves in the axils; in summer. ([Greek: Naia/s], _a water-nymph_.)

1. N. marina, L. _Stem rather stout and often armed with broad prickles; leaves broadly linear_ (3--18'' long), _coarsely and sharply toothed_, the dilated base entire; fruit 2--21/2'' long; _seed very finely lineate, oblong_, slightly compressed. (N. major, _All._)--Marshes and salt-springs of western N. Y. and Mich. Teeth of one or more brownish cells upon a many-celled base. (Eu.)

Var. gracilis, Morong. Internodes long (1--3') and nearly naked, with only a few teeth above; leaves very narrow, the dilated base also toothed; fruit smaller.--Canoga marshes, western N. Y.; also in Fla.

Var. recurvata, Dudley. Stems short, inclined to be dichotomously branched, recurved-spreading; leaves usually recurved, the teeth prominent, the dilated base with a projecting tooth each side.--Cayuga marshes, N. Y.

2. N. flexilis, Rostk. & Schmidt. _Stems usually very slender; leaves very narrowly linear_ (1/2--1' long), _very minutely serrulate_; fruit 11/2'' long, narrowly oblong; _seeds lance-oval, smooth and shining_.--Ponds and slow streams, N. Scotia to S. C., Iowa and Minn. Teeth on the margins of the leaves 1-celled. (Eu.)--Var. ROBUSTA, Morong. Stem stout, few-leaved, sparsely branching, elongated; leaves flat, abruptly acute.--E. Mass., Mich., and Tex.

3. N. Indica, Cham., var. gracillima, A. Br. Branches alternate; _leaves_ very narrowly linear, _nearly capillary_, straight, _serrate, the rounded lobes of the sheathing base spinulose-ciliate; fruit linear, impressed-dotted between the numerous ribs_.--Mass. to Penn., west to Ind. and Mo. Teeth of 3 cells each.

ORDER 127. ERIOCAULEAE. (PIPEWORT FAMILY.)

_Aquatic or marsh herbs, stemless or short-stemmed, with a tuft of fibrous roots, a cluster of linear and often loosely cellular grass-like leaves, and naked scapes sheathed at the base, bearing dense heads of monoecious or rarely dioecious small 2--3-merous flowers, each in the axil of a scarious bract; the perianth double or rarely simple, chaffy; anthers introrse_; the fruit a _2--3-celled 2--3-seeded capsule_; seeds pendulous, orthotropous; embryo at the apex of mealy albumen.--Chiefly tropical plants, a few in northern temperate regions.

1. Eriocaulon. Perianth double, the inner (corolla) tubular-funnel-form in the staminate flowers; stamens twice as many as its lobes (4). Anthers 2-celled.

2. Paepalanthus. Perianth as in the last; stamens only as many as the corolla-lobes (3). Anthers 2-celled.

3. Lachnocaulon. Perianth simple, of 3 sepals. Stamens 3, monadelphous below. Anthers 1-celled.

1. ERIOCAULON, L. PIPEWORT.

Flowers monoecious and androgynous, i.e. both kinds in the same head, either intermixed, or the central ones sterile and the exterior fertile, rarely dioecious. _Ster. Fl._ Calyx of 2 or 3 keeled or boat-shaped sepals, usually spatulate or dilated upward. Corolla tubular, 2--3-lobed, each of the lobes bearing a black gland or spot. Stamens twice as many, one inserted at the base of each lobe and one in each sinus; anthers 2-celled. Pistils rudimentary. _Fert. Fl._ Calyx as in the sterile flowers, often remote from the rest of the flower (therefore perhaps to be viewed as a pair of bractlets). Corolla of 2 or 3 separate narrow petals. Stamens none. Ovary often stalked, 2--3-lobed, 2--3-celled; style 1; stigmas 2 or 3, slender. Capsule membranaceous, loculicidal.--Leaves mostly smooth, loosely cellular and pellucid, flat or concave above. Scapes or peduncles terminated by a single head, involucrate by some outer empty bracts. Flowers, also the tips of the bracts, etc., usually white-bearded or woolly. (Name compounded of [Greek: e)/rion], _wool_, and [Greek: kaulo/s], _a stalk_, from the wool at the base of the scape.)--Our species are all stemless, wholly glabrous excepting at the base and the flowers, with a depressed head and dimerous flowers.

1. E. decangulare, L. _Leaves obtuse_, varying from linear-lanceolate to linear-awl-shaped, rather rigid; scapes 10--12-ribbed (1--3 deg. high); head hemispherical, becoming globular (2--7'' wide); scales of the involucre acutish, straw-color or light brown; _chaff_ (bracts among the flowers) _pointed_.--Pine-barren swamps, N. J. to Fla. July--Sept.

2. E. gnaphalodes, Michx. _Leaves spreading_ (2--5' long), _grassy-awl-shaped_, rigid, or when submersed thin and pellucid, tapering gradually to a _sharp point_, mostly shorter than the sheath of the _10-ribbed scape_; scales of the involucre very obtuse, turning lead-color; _chaff obtuse_.--Pine-barren swamps, N. J. to Fla.

3. E. septangulare, Withering. _Leaves short_ (1--3' long), _awl-shaped, pellucid_, soft and very cellular; _scape 4--7-striate_, slender, 2--6' high, or when submersed becoming 1--6 deg. long, according to the depth of the water; _chaff acutish_; head 2--3'' broad; the bracts, chaff, etc., lead-color, except the white coarse beard.--In ponds or along their borders, Newf. to N. J., west to Ind., Mich., and Minn. July, Aug. (Eu.)

2. PAEPALANTHUS, Martius.

Stamens as many as the (often involute) lobes of the funnel-form corolla of the sterile flowers, and opposite them, commonly 3, and the flower ternary throughout. Otherwise nearly as in Eriocaulon. (Name from [Greek: paipa/le], _dust_ or _flour_, and [Greek: a)/nthos], _flower_, from the meal-like down or scurf of the heads and flowers of many South American species.)