Chapter L: VULGARIS, Raddi. Thallus 1--2' long, forked, innovating from the

apex, with a somewhat diffuse costa; peduncle very hairy, 1--11/2' long.--Introduced into greenhouses; always sterile, but easily recognized by the characteristic receptacles. (L. cruciata, _Dumort._) (Int. from Eu.)

ORDER 140. RICCIACEAE.

Plant-body a dichotomously branching thallus, terrestrial or aquatic. Capsules short-pedicelled, or sessile on the thallus, or immersed in its substance, free or connate with the calyptra, globose, at length rupturing irregularly. Calyptra crowned with a more or less deciduous point. Elaters none. Spores usually angular, reticulate or muriculate. Antheridia ovate, immersed in the thallus in flask-shaped cavities with protruding orifices (_ostioles_).

1. Riccia. Capsule immersed in the thallus. Involucre none.

2. Sphaerocarpus. Capsule sessile on the thallus. Involucre inflated-pyriform.

1. RICCIA, Micheli. (Pl. 22.)

Thallus at first radiately divided, the centre often soon decaying; the divisions bifid or di--tri-chotomous, flat or depressed or channelled above, usually convex and naked or squamulose beneath; margins naked or spinulose-ciliate; epidermis usually distinct, eporose; air-cavities evident or wanting. Capsule immersed, sessile. Calyptra with a persistent style. Spores alveolate or muriculate, usually flattened and angular. (Named for _P. F. Ricci_, an Italian nobleman, patron of Micheli.)

Sec. 1. LICHENODES. _Fruit mostly protuberant above; spores about 84 mu broad, issuing through openings in the upper surface of the thallus; terrestrial species (on damp, usually trodden or cultivated ground), without air-cavities._

[*] _Thallus naked, without cilia or scales._

1. R. Frostii, Aust. Thallus orbicular, 6--12'' broad, thinnish, grayish-green, the apex and narrowly membranous margins sometimes purplish, minutely pitted; divisions linear or subspatulate, subtruncate and slightly emarginate; rootlets smooth or obsoletely papillose within; capsules very prominent beneath; spores barely 50 mu broad, nearly round, somewhat margined, with depressed sides when dry, fuscous.--Ohio, Ill., and westward.

[*][*] _Thallus with white scales beneath (dark purple in n. 4), the margin naked._

2. R. sorocarpa, Bisch. Thallus 3--8'' in diameter, pale green becoming whitish, finely reticulate, subradiately or dichotomously divided, the oblong-linear segments subacute, deeply sulcate, with a few inconspicuous scales toward the apex not extending beyond the margin; margins erect when dry; spores issuing through chinks early appearing along the groove above.--Thin rocky soil and cultivated fields, Closter, N. J. (_Austin_), western N. Y. (_Clinton_), and Ill. (_Hall_). (Eu.)

3. R. lamellosa, Raddi. Thallus pale green, elegantly reticulated, subradiately divided, the divisions obovate or obcordate, bifid or 2-lobed, 2--5'' long, channelled at the apex, with membranous ascending margins, and furnished beneath with transverse scales which extend considerably beyond the margin; spores much as in n. 2.--Thin rocky soil, Closter, N. J. (_Austin_).

4. R. nigrella, DC. Thallus dichotomously divided, the divisions linear, channelled, with entire narrowly membranous margins, green above, dark purple beneath and furnished with transverse semicircular scales not exceeding the margin.--Rocky ground, N. Y. (_Torrey_), and Chester, Penn. (_Porter_). (Eu.)

[*][*][*] _Thallus more or less ciliate, naked beneath or obsoletely squamous along the extreme edge._

5. R. arvensis, Aust. Thallus much divided, 3--9'' broad, papillose-reticulate, dull green both sides, becoming fuscous above, the flat margins at length purple; divisions sulcate, dichotomous, the linear-elliptic or subspatulate lobes acutish and obsoletely emarginate; cilia whitish, very short and inconspicuous or nearly wanting; capsules aggregated toward the apex; spores 71--84 mu broad, dark fuscous, reticulate, with pellucid margin.--Var. HIRTA, Aust., decidedly ciliate and with spine-like hairs scattered over the upper surface; divisions broader, more obtuse; spores nearly black, larger (84--101 mu) and smoother.--Cultivated fields and (the var.) rocky places, Closter, N. J. (_Austin_).

6. R. Lescuriana, Aust. Stellately or subcruciately divided, the obcordate or cuneate-linear divisions 2--6'' long, punctate-reticulate, subglaucous or ashy-green both sides or becoming purple beneath, the slightly concave lobes emarginate, closely ciliate with short obtuse spine-like white hairs; capsules scattered, chiefly near the base of the divisions; spores 71--83 mu broad, dark brown, reticulate, not margined.--Cultivated fields and rocky grounds, N. J. to Ill., and southward.

Sec. 2. SPONGODES. _Thallus with large air-cavities usually opening by pits through the upper surface, and with slight depressions over the capsules which are prominent beneath; spores 41--51 mu broad, obtusely angular or globose; terrestrial._

7. R. crystallina, L. Orbicular, 6--9'' broad, the obcordate or cuneate divisions bifid or 2-lobed, flat above and the surface much broken up into pits, the margins subcrenate; capsules scattered; spores issuing through the upper surface.--On mud flats, Ill. (_Hall_), west and southward. (Eu.)

8. R. lutescens, Schwein. Orbicular, 1--11/2' in diameter, light green; divisions 6--8, linear, 2--3 times forked, narrowly channelled, obcordate and thickened at the apex, with delicate whitish obliquely ovate appressed scales, rootlets wanting beneath above the middle; fruiting plant unknown.--Dried up pools and ditches, Canada to Mo., and southward. An analogous form has been developed by Lindberg from R. natans.

9. R. tenuis, Aust. Thallus thin, olive or yellowish-green, shining, the 2--4 divisions roundish-obovate, 2--4'' long, flat, with sinuate margins, green beneath with a slender costa and few rootlets; capsule very delicate, closely adherent to the substance of the thallus, minutely apiculate; spores round or short-oval, conspicuously depressed at one end when dry.--Wet ground in open woods, Closter and Lawrence, N. J. (_Austin_), and Mo. (_Hall_).

Sec. 3. RICCIELLA. _Thallus linear, dichotomous, floating or rarely terrestrial; capsule protuberant from the lower surface._

10. R. fluitans, L. Thallus often in extended patches, thin, green, radiately expanding, the often imbricate divisions 1/2--11/2'' wide, parallel-nerved, flat, without rootlets, cavernous only toward the slightly dilated very obtuse or subtruncate apex; capsules present only in some terrestrial forms, very prominent below, rupturing beneath the apex.--Very variable. The most notable form is var. SULLIVANTI, Aust., with divisions about 1/2'' wide, channelled, cavernous throughout, the margins crisped-crenulate, and rootlets numerous on the costa tumid with abundant capsules, which are tipped with a long funnel-mouthed point; spores obscurely angled, reticulate and margined. (R. Sullivanti, _Aust._)--In ponds or ditches or growing in wet places upon the ground; the variety often in cultivated fields. (Eu.)

Sec. 4. RICCIOCARPUS. _Thallus obcordate, floating or rarely terrestrial; capsules not protruding, at length exposed by a cleft in the central groove._

11. R. natans, L. (Pl. 22.) Divisions obcordate or cuneate, broadly emarginate, 3--6'' long, purplish, very narrowly channelled, with numerous uniform air-cavities beneath the epidermis, rooting toward the base and at length with dark purple scales beneath the apex; capsules in 1 or 2 rows beneath the groove; spores black, angular, strongly papillose.--Canada to the Gulf. (Eu.)

2. SPHAEROCARPUS, Micheli. (Pl. 22.)

Thallus lobed, without costa or epidermis. Involucres sessile, obconic or pyriform, perforated at the apex, continuous with the thallus at base. Calyptra closely investing the single globose indehiscent capsule, crowned with a deciduous point. Spores globose, muriculate, remaining united in a coccus. Antheridia borne in follicular bodies on the surface of a separate thallus.--An anomalous genus, perhaps more closely related to the Jungermanniaceae. (Name from [Greek: sphai~ros], _a sphere_, and [Greek: karpo/s], _fruit_.)

1. S. terrestris, Smith. Thallus orbicular, 3--6'' broad, covered by the clustered inflated involucres, which are nearly 1'' long, 3--4 times the length of the capsule; coccus 102--127 mu wide, indistinctly lobed. (S. Michelii, _Bellardi_.)--In cultivated fields, mostly southern. (Eu.)

ADDITIONS AND CORRECTIONS.

Page 59.--ARGEMONE MEXICANA. Collected at Merodosia, Ill., with white flowers, by _A. B. Seymour_.

Page 75.--Insert after Cleome integrifolia--