Chapter LXI: Appendix: List of Notes (2)

_Arenaria (Honckeneya) peploides._ The seeds float for many months in sea-water unharmed, 75 per cent. floating after a year. They never germinate in sea-water; but on being transferred to fresh water after many months in sea-water they germinate healthily in a few days. These seeds only float a few days in fresh water, all sinking within 10 days, and even after a year’s drying they sink in a week or two. Precisely the same results were produced in my experiments in 1892 on Cornish seeds, and in 1904 on Devonshire seeds. In the great contrast between their floating capacity in sea-water and in fresh water the seeds of this plant defy the general rule that seeds that float a long time in sea-water float also a long time in fresh-water. According also to Sernander the seeds float a long time in the sea. He says that the capsules float, but since they ultimately dehisce this could scarcely be efficacious in dispersal. Floating portions of the plant also aid in its dispersal, according to the same authority (p. 174). The plant forms great extended masses on the pebbly shores of Spitzbergen (Ekstam, p. 28).

_Beta maritima._ Thuret found that the dried fruits of this plant floated only two or three days in sea-water; whilst in my sea-water experiments the freshly gathered fruits floated only one or two days. Sernander speaks of them as fitted for dispersal from shore to shore; but this could only be to a limited extent. Martins and Thuret established by experiment the capacity of the germination of seeds of other species of Beta after long immersion in sea-water; and the first seems to imply that those of Beta vulgaris float for many weeks; but I am inclined to think an error lies here.

_Cakile maritima._ The fruits, even after long drying, float, as a rule, only a week and sink within ten days, the same results being afforded in my sea-water experiments in 1893 on fruits from Cornwall, and in 1904 on fruits from Devonshire. The fruits are common in the stranded drift on the north coast of Devonshire and may often be seen germinating there. They are also frequent in the beach drift of the Scandinavian coasts (Sernander, p. 156).

_Crambe maritima._ The fruits were kept floating by Sernander more than 13 days (p. 165). Martins implies that they floated for 45 days. Darwin says that they germinated after 37 days’ immersion in sea-water, but does not specify that they floated all the time.

_Crithmum maritimum._ The ripe fruits readily separate into the two carpels, which are very buoyant and float in sea-water for months. In my experiments, 95 per cent. remained afloat after 10 months. It is remarkable that whilst in sea-water the spongy covering of the carpels retains its vitality, in fresh-water it becomes sickly and decays and the carpels lose their floating power, so that they float weeks instead of months as in the sea-water. The carpels are extremely light, being washed up in the spray and blown up by the wind amongst the lightest of the stranded drift of the Devonshire beaches. In a moderate gale they are often blown off the beach and up the cliff-faces.

_Convolvulus soldanella._ From 40 to 50 per cent. of the seeds float after six months in sea-water, and about 30 per cent. float after eighteen months, retaining up to the end their germinating capacity. Sernander implies that the plant is not found on the Scandinavian coast to the north of Nissum Fjord in Denmark. It is known, however, to occur in the south of Scotland. (I am indebted to Mr. Millett for his extremely kind assistance in experimenting on this plant about ten years since.)

_Eryngium maritimum._ The fruits float in sea-water, as a rule, only 3 or 4 days and all sink within a week. After drying for three months, the floating period is only increased by a day or two. Though not at all suited for transport for any distance by the currents, the carpels, on account of their long prickly calyx teeth, would readily become entangled in a bird’s plumage, and doubtless they are dispersed usually in that fashion.

_Euphorbia paralias._ The seeds float a long time unharmed in the sea. In my experiments at least 90 per cent. remained afloat after six weeks in sea-water. On account of their small size they are liable to be overlooked in beach drift; but they are to be found stranded on the sands of our southern coasts, and they came under my notice in abundance in the seed-drift of the Sicilian beaches.

_Glaucium luteum._—The seeds have no proper buoyancy even after prolonged drying. On account of their oiliness they will float at first on still water; but they can be made to sink at once or in a day by dropping water upon them. The mode of dispersal is problematical.

_Lathyrus maritimus._—The seeds are evidently able to float a long time. They were, according to Sernander (p. 178), found in quantities by J. Schmidt cast up on some sand-islets near Falster in Denmark; and the plant is regarded by Norman as distributed over the coasts of Arctic Norway through the agency of the currents. They have, as observed by Schmidt, considerable floating powers. Some small leguminous seeds, seemingly of this species, which I found in the beach drift of Woollacombe Sands, Devonshire, floated uninjured for many weeks in sea-water.

_Matricaria maritima,_ maritime variety of M. inodora. The fruits floated in my experiments unharmed after eight months in sea-water. In an experiment made some years since on the fruits of the inland form I noted that they had little or no buoyancy; but it is necessary to repeat the observation. Sernander (p. 181) supports Norman’s view that these plants are spread by the currents in Arctic Norway. The fruits occur in the Baltic sea-drift and also in fresh-water drift. M. inodora is found on sandy beaches in Nova Zembla. I am inclined to regard the maritime form from the dispersal standpoint as a distinct species.

_Polygonum maritimum._—I have made observations on this plant in Devonshire, the Lipari Islands, and the coast of Chile. As in the case of several other species of Polygonum tested by me the fruits have little or no buoyancy, but inclosed in the perianth they float three or four days. The entire plant floats; but portions placed in sea-water sank within five or six days. Shore-birds can alone explain the wide distribution of this species.

The structural characters of some of these fruits or seeds are in their relation to buoyancy discussed on page 115. It may be here observed that the valuable results obtained by Prof. Martins in testing the germinating capacity of the fruits and seeds of several of the shore-plants above mentioned, after long immersion in sea-water, are at times not to be depended on for the flotation indications, the persistence of the seed’s vitality being the special purpose of his research. His negative results as regards germination are not, however, always conclusive, since the period employed from April to June was quite insufficient. In many of my experiments seeds after long flotation in sea-water did not germinate for a year or more afterwards. If his investigation had been extended, the opinion that the Ranunculaceæ, the Malvaceæ, and the Convolvulaceæ are apparently least able to resist the action of sea-water would never have been formed. A very large amount of evidence now shows that most seeds or fruits that are at all well protected will germinate after long immersion in sea-water. But all experiments must be well safeguarded and extended over a year or two. The necessity of this was long since shown by Thuret. By employing double sets of seeds he ascertained that in a third of the species germination failed not only in the case of the seeds immersed in sea-water, but also in those that had not been placed in sea-water at all. Future investigators may, however, regard the buoyant qualities of seeds or fruits with their associated structural characters as offering now the true line of research. Observers beginning with Berkeley and Darwin down to the present time have quite established the fact that seeds as a rule germinate freely after long sea-water immersion.

NOTE 19 (page 35)

ON GERMINATION IN SEA-WATER

During my experiments on the buoyancy of about 270 British plants, about a fourth of them (including most of those with buoyant seeds or fruits) were subjected to prolonged immersion in sea-water from periods varying from six to thirty-three months. If we except plants like Aster tripolium, Salicornia herbacea, Triglochin maritimum, &c., that live normally in salt marshes, or on the muddy banks of estuaries, only one of the whole number, namely, Ranunculus sceleratus, displayed the capacity of germination in sea-water. Amongst the plants that failed may be mentioned the following that are confined to the sea-beach—Arenaria peploides, Cakile maritima, Convolvulus soldanella, Eryngium maritimum, Euphorbia paralias, Glaucium luteum, and we may here include Crithmum maritimum of the rocky coasts. Of the beach-plants that also grow inland, Silene maritima and Spergularia rubra (excepting the form found on muddy coast flats) likewise failed. Amongst the plants of miscellaneous inland stations that failed were Atriplex patula, Bidens cernua, B. tripartita, Calla palustris, several species of Carex both from dry and wet situations, Convolvulus arvensis, C. sepium, Hydrocotyle vulgaris, Iris pseudacorus, several species of Juncus, Lycopus europæus, Mentha aquatica, Ranunculus repens, Rhinanthus crista galli, several species of Rumex, Scutellaria galericulata, Sparganium ramosum, &c.

In nearly all the plants that failed to germinate in sea-water the capacity of readily germinating in fresh water was displayed. The restraining power of immersion in sea-water was illustrated over and over again in my experiments. During the course of an experiment seeds removed from the sea-water vessel and placed directly in a vessel of fresh water kept beside the other germinated in a few days, whilst those left in the sea-water never germinated, though often kept there for months after. It was also noticeable that a previous sea-water immersion favoured early germination in fresh water. It may be added that most of the experiments were on floating seeds and seedvessels, though germination also occurred in the sunken state.

It was ascertained in the exceptional case of Ranunculus sceleratus, that although germination took place in sea-water, it was only after a prolonged soaking of months had prepared the way. Of a number of its seed-like fruits placed in fresh water and in sea-water in April and kept under the same conditions, those in fresh water germinated freely in a week or two, whilst those in sea-water did not begin to germinate until the following October. Whilst the floating seedlings produced by germination in fresh water grew vigorously and developed roots, those resulting from germination in sea-water and left in the vessel only attained a length of four millimetres in two months, developed no roots, and showed only the first leaf. The sea-water seedlings were pale green, and in their stout fleshy appearance contrasted greatly with the slender fresh-water seedlings.

With regard to the germination in sea-water of the plants of the salt marsh and of the mud-flats of estuaries, the following observations may be made. With Aster tripolium the seeds germinate readily in sea-water even when its density is raised by evaporation to 1·040; and I think that by a carefully graduated series of experiments they could be induced to germinate in brine. The seeds of Salicornia herbacea germinate in sea-water more readily than in fresh water; and the sea-water seedling is much the more vigorous and healthy of the two. I kept the floating seedlings in sea-water for about ten weeks from the date of germination, when they had developed the second joint and were throwing out rootlets. After that, unless placed in salt-mud, they became sickly and died. The floating seedling can evidently disperse the species. I found with Spergularia marina, the maritime form of S. rubra, that seeds of the plants growing on a sandy beach did not germinate in sea-water, only those from plants growing on muddy coast-flats doing so. But the sea-water seedlings, unlike those of Salicornia herbacea, but like those of Ranunculus sceleratus, when left in sea-water did not thrive. The seeds of Triglochin maritimum, as well as those of T. palustre, behave very similarly in sea-water, germinating readily, the liberated seedlings thriving afloat and producing the plumule. The ultimate test of the capacity for germinating in sea-water seems to lie in the behaviour of the seedling when left in the sea-water. Unless it belongs to a characteristic plant of the salt marsh or of the estuary, like Salicornia, it makes but little attempt at growth whilst afloat in sea-water, showing no rootlets, though at times developing the plumule.

The germination of seeds in sea-water also attracted the notice of Darwin; but his results in some respects are scarcely those I should have looked for (_Gardener’s Chronicle_, May, 1855, and _Journ. Linn. Soc._, vol. i., p. 130, 1857). Out of the seeds of 87 plants placed in sea-water to test their capacity of germination when afterwards planted, in three cases, those of Tussilago farfara, Convolvulus tricolor, and the garden Orache (Atriplex), the seeds germinated under the water, the freed seedlings, as with the two first named plants, living in the sea-water for some time after. Darwin was evidently himself surprised at these results, and I am quite unable to understand them. In England and in the tropics I have carried on prolonged sea-water experiments on the seeds of at least fifteen species of Convolvulus and Ipomœa (including the beach plants C. soldanella and I. pes capræ) and have never obtained such a result. The seeds will nearly always germinate well in fresh water; but in sea-water the process begins, as indicated by the swollen seed, and then aborts, the embryo dying (see page 83). The seeds of Atriplex patula, though a long time in sea-water in my experiments, made no attempt to germinate there. Neither Prof. Martins, who experimented upon the effects of sea-water immersion on the seeds of nearly 100 plants, including many coast species, nor M. Thuret, who experimented in sea-water on the seeds of 251 plants, the experiments being in some cases prolonged for more than a year, make any reference, as far as I could gather from their writings, to any cases of germination in sea-water. Darwin’s results, however, are always significant in matters of dispersal; and perhaps one of my readers will be able to experiment again on his three plants.

When in Hawaii, I made some observations on the germination of Batis maritima in sea-water, a plan with which I was also familiar in its home in the salt-water pools of the coast of Peru. The mature fruits, on being freed from the parent plant in sea-water, float away, and in from one to two weeks they break down from decay, setting free the seeds. The seeds float in sea-water indefinitely, their buoyancy only terminating with their germination, the first seeds germinating afloat about six weeks after the breaking down of the fruit, whilst the rest continue to float in the sea-water during the next three months, some of them germinating at intervals, and all of them doing so eventually. Strange to say, although the seedlings remained healthy whilst afloat in the sea-water, they made no effort either to separate the cotyledons or to produce a plumule.

NOTE 20 (page 42).

ON THE MAXIMUM HEIGHTS REACHED BY SOME SHORE PLANTS IN THEIR EXTENSION
INLAND IN VANUA LEVU, FIJI

Since they occupy the “talasinga” districts described in the following note, these shore plants would be expected to extend as high as those districts extend, namely, to about 1,500 feet above the sea. This indeed represents their limit excepting in one instance; but many fall considerably short of this elevation.

_Canavalia obtusifolia_, variety, 700 feet, rare. _Cassytha filiformis_, 950 feet. _Cerbera Odollam_, 1,200 feet: 2,600 feet in one exceptional case on the slopes of Mbatini. _Colubrina asiatica_, 400 feet. _Cycas circinalis_, 1,100 feet. _Derris uliginosa_, 1,000 feet, rare. _Ipomœa pes capræ_, 1,300 feet. _Morinda citrifolia_, 700 feet. _Scævola Kœnigii_, not common inland, and rarely over 100 feet above the sea; but it may occur miles from the beach, as near Vatu Levoni, where a few stunted plants were growing five miles from the coast. _Vitex trifolia_, 1,300 feet, usually more or less unifoliolate and procumbent.

Unless otherwise stated all the plants above named are common inland, as also are _Premna tahitensis_, _Tacca pinnatifida_, _Tephrosia piscatoria_, _Hibiscus tiliaceus_, &c.; but I have made no note of _Thespesia populnea_ occurring far off the beach.

NOTE 21 (pages 42, 43)

ON THE DWARFING OF SHORE PLANTS WHEN EXTENDING INLAND INTO THE
“TALASINGA” PLAINS IN VANUA LEVU.

_Premna tahitensis_, 9 or 10 feet high at the coast, may here be only 3 feet high. Other trees like _Morinda citrifolia_ become also stunted. _Cerbera Odollam_, a moderate-sized tree at the coast, may in the “talasinga” plains be only 4 to 6 feet high, but it here displays distinct varietal characters. Whilst the shore trees of Cerbera Odollam have broad leaves (length 3 times the breadth) with obtuse points, and short, stout flower-peduncles (1-1/2 - 2 inches), the inland or “talasinga” species has long lanceolate leaves (length 7 or 8 times the breadth), and long, slender flower peduncles (3 inches). However, intermediate forms are common, the broad-leaved coast tree approaching the inland plant and _vice versâ_.

NOTE 22 (page 43)

THE “TALASINGA” PLAINS OF VANUA LEVU, FIJI

Amongst the most conspicuous features of the north and north-west or lee sides of the large islands of Vanua Levu and Viti Levu are the extensive rolling plains that extend from the sea-border for some miles inland to the foot of the mountains. It is to those of the first-named island that the following remarks strictly apply; but no doubt they will serve equally well for those of the other island. In the first volume on the geology of Vanua Levu, reference is frequently made to this subject, and the reader may profitably look at the remarks there made.

Here the mountain-forests more or less abruptly cease, and we have an undulating region of grass, reeds, and ferns dotted over with Casuarinas, Pandanus trees, Cycads, Acacias, and shrubby growths. Though the list of plants characteristic of these plains is not small, they are not, as a rule, numerous in any one locality, and the general appearance is one of aridity. A dry, crumbling soil, often deeply stained by iron-oxide, is plentifully exposed; and blocks of basic volcanic rocks in all stages of disintegration are strewn over the surface in many localities. Rivers, fed by the heavy rainfall of the forested slopes of the mountains, traverse these regions, but, as a rule, receive no tributaries; and the districts have, in fact, well earned the name given to them by the natives of the “talasinga,” or sun-burnt, lands.

The vegetation, though sparse and scanty in comparison with that of the forests, is sufficiently varied when it comes to be more closely examined. In one locality we may have extensive tracts covered with Gleichenia, Pteris, and other ferns of the bracken habit. In another, tall reeds (Eulalia) and grasses cover large areas. Here, more than one species of Tacca (T. pinnatifida and T. maculata) thrive. There, the Turmeric (Curcuma longa) abounds. Trailing over the soil in one place we notice Ipomœa pes capræ, in another the Yaka (Pachyrrhizus trilobus), and in another the procumbent unifoliolate form of Vitex trifolia. Amongst the shrubs and small trees we observe in different localities the Sama (Commersonia echinata), the Mbulei (Alstonia plumosa—one of the rubber plants), Mussænda frondosa, Melastoma denticulatum, and Nelitris vitiensis, the Nunga-nunga. Dodonæa viscosa, found in similar regions in Australia and New Zealand, abounds in places; and here and there may be seen species of Hibbertia, another Australian genus. Fagræa Berteriana, the Mbua tree, grows abundantly in certain districts, as in the Mbua plains, and Gardenias are at times abundant. One or two characteristic beach-plants have been already mentioned, and amongst others particularly frequent in these plains are Cassytha filiformis, Cerbera Odollam, Morinda citrifolia, and Premna tahitensis.

When these talasinga districts approach the forests, patches of wood occur at intervals, and we observe here the Candle-nut Tree (Aleurites moluccana), the Vunga (Metrosideros polymorpha), and the Thau-kuro (Casuarina nodiflora). Such are some of the botanical features of these districts; but the reader will acquire a sufficiently correct general notion of the floral physiognomy of these regions if he bears in mind their most conspicuous characters, those of an undulating region more or less covered with ferns, tall reeds, and grass, and dotted over, either separately or in clumps, with Casuarinas (C. equisetifolia), Screw-pines (Pandanus odoratissimus), Cycads (C. circinalis), and Acacias (A. Richii, &c.).

However, the peculiar vegetation of these plains often ascends the lower slopes of the mountains, reaching to various elevations. In Vanua Levu it often ceases at 900 or 1,000 feet, but it may only reach to 400 or 500 feet, and, on the other hand, not uncommonly it ascends to as much as 1,500 feet, the greatest elevation recorded by me being 1,600-1,700 feet in the Sealevu district. It extends miles inland, and where conditions are suitable it may reach the heart of the island.

Different explanations have been offered of the origin of the peculiar vegetation of the leeward slopes of these islands. It is, however, a phenomenon that is presented over much of the globe by islands lying in the track of regular winds, the weather, or wet, side being densely wooded, whilst the lee, or dry, side is covered with grass, ferns, and similar vegetation. The predisposing cause must be climatic; and although Mr. Horne’s explanation attributing it to the effect of fires and to a faulty system of native cultivation (pp. 80, 132) may be doubtless true in certain localities, the influences at work here must be the same as are at work in other islands and on continental coasts in other parts of the world.

But for all that it is not easy to give a definite explanation even from a meteorological standpoint. Those who are interested in this subject will recall the desert districts of Australia and the dreary sandy wastes of the coast of Northern Chile and Peru; and they will be cautious in venturing on a definite explanation even with such relatively unimportant examples of the same principle as are exhibited by the islands of Fiji. Dr. Seemann, writing of these “talasinga” plains (p. xii), remarks that “their very aspect is proof that rain falls in only limited quantity,” the mountainous backbone of the islands intercepting, as he holds, much of the rainfall. But the subsequent observations of Mr. Holmes, at Delanasau, in the “talasinga” district on the north-west side of Vanua Levu, have shown that there is by no means a small rainfall in this locality, the average rainfall, for instance, for the seven years ending December, 1877, being 113 inches, which must be quite two-thirds or three-fourths of the fall on the weather side of the island (see p. 215); whilst the average number of days on which rain fell was 156. The true cause would seem to lie in the excessive dryness of the air on the lee side of the islands between the rains, and the whole matter may, perhaps, be one rather for the hygrometer than for the rain-gauge. I have no comparative data bearing on this point; but Mr. Holmes, whose observations as here quoted are from Horne’s _Year in Fiji_, found that the mean relative humidity for 1875 at 1 P.M. was 63, which is certainly very low for the tropics. I may remark that, as far as personal experience goes, the climate on the lee side of Vanua Levu is much more enervating, much less healthy, and the air is far more “drying” than on the side exposed to the trade-wind.

Geological characters, as I found, explained nothing in this connection, the “talasinga” vegetation sometimes occurring on basaltic areas, at other times on the “soapstone” or calcareous mud-stone, and again on coarser tufaceous rocks. In my volume on the geology of Vanua Levu (p. 57), it is pointed out that the extensive disintegration of the basaltic rocks, that are exposed on these plains in places, affords evidence of the great antiquity of these “talasinga” districts in their present unforested condition. The extent to which these rocks have weathered downward is remarkable. In some places they are decomposed to a depth of ten feet and more. The same inference is to be drawn from the occurrence of fragments of limonite, or bog-iron ore, over these plains, marking as they do original swampy tracts that, with a few exceptions, have long since disappeared. Such deposits indicate that these plains have been for ages in the same condition. ... It may be added that, according to Mr. Lister and Mr. Crosby, the features of the “talasinga” plains occur in the Tongan Group on the leeward sides of the islands of Eua and Vavau.

NOTE 23 (page 43)

SCHIMPER’S GROUPING OF THE INDO-MALAYAN STRAND-FLORA

It is divided into four formations—the Mangrove, the Nipa, the Barringtonia, and the Pes-capræ. The two last make up my Beach-formation, the Barringtonia formation comprising the trees, shrubs, &c., immediately lining the beach, and the Pes capræ including the creepers and bushes of the beach itself. In the Pacific islands it is not always easy to preserve this distinction. The Nipa formation corresponds in some respects with my Intermediate or Transition formation, lying as it does between the mangrove-belts and the woods of the interior; but the swamp-palm (Nipa fruticans) that forms it in the mass is not found in Fiji or, indeed, in the Pacific islands, excepting the Solomon and Caroline Groups.

NOTE 24 (page 44)

GROUPING OF SOME OF THE CHARACTERISTIC PLANTS OF THE STRAND-FLORA OF
FIJI

(a) _Beach-formation._—Calophyllum inophyllum, Thespesia populnea, Triumfetta procumbens, Carapa moluccensis, Canavalia obtusifolia, Vigna lutea, Pongamia glabra, Sophora tomentosa, Cæsalpinia Bonducella, Acacia laurifolia, Barringtonia speciosa, Terminalia Katappa, Gyrocarpus Jacquini, Pemphis acidula, Morinda citrifolia, Guettarda speciosa, Wedelia biflora, Scævola Kœnigii, Cordia subcordata, Tournefortia argentea, Ipomœa pes capræ, Cassytha filiformis, Hernandia peltata, Pandanus odoratissimus, &c.

(b) _Mangrove-formation._—Carapa obovata, Rhizophora mucronata, Rhizophora mangle, Bruguiera Rheedii, Lumnitzera coccinea, Scirpodendron costatum, &c. (See below.)

(c) _Intermediate or Transition-formation._—Hibiscus tiliaceus, Heritiera littoralis, Smythea pacifica, Derris uliginosa, Entada scandens, Barringtonia racemosa, Cerbera Odollam, Clerodendron inerme, Vitex trifolia, Excæcaria Agallocha, &c.

N.B.—It is not possible to draw a definite line between the plants of the mangrove swamp and those of the tracts around. Several of the plants placed in the intermediate formation, such as Heritiera littoralis, Entada scandens, Excæcaria Agallocha, &c., are just as much at home amongst the mangroves. In the same way it is often difficult to distinguish between the Beach and the Intermediate formations, and plants like Cerbera Odollam, Hibiscus tiliaceus, and Vitex trifolia belong equally to both.

NOTE 25 (page 47)

THE STRAND-FLORA OF THE TAHITIAN REGION

Drake del Castillo’s _Flore de la Polynésie française_ deals mainly with the Society or Tahitian Islands, but also with the Marquesas, Paumotus, Gambier Islands, and Wallis Island. The last-named, however, lies in Western Polynesia, and is not dealt with in this connection. There is no reason to believe, judging from the general character of the islands and from Cheeseman’s memoir on the Rarotongan flora, that the strand-plants of the islands of the Cook and Austral Groups, which also belong to this region, differ materially from those of the Tahitian islands proper. Rarotonga, however, possesses Entada scandens, not recorded as a growing plant from any other part of East Polynesia, excepting perhaps Mangaia in the same group.

NOTE 26 (page 48)

THE FIJIAN SHORE-PLANTS NOT FOUND IN TAHITI

Although most of these plants, such as Barringtonia racemosa, Clerodendron inerme, Entada scandens, Excæcaria Agallocha, Heritiera littoralis, Smythea pacifica, &c., have fruits that float for months, and could have reached Tahiti as readily as some of the beach-plants that have successfully established themselves, there are a few like Dalbergia monosperma, Derris uliginosa, and Scirpodendron costatum, the fruits of which only float for weeks, and it is possible that they may have been unable to reach there.

NOTE 27 (page 49)

THE INTRUDERS INTO THE BEACH-FLORA FROM THE INLAND PLANTS OF TAHITI

Drake del Castillo mentions several, such as species of Boerhaavia, that could only be occasional intruders; but it is noteworthy that Gardenia tahitensis appears to be a genuine recruit from inland. The xerophilous habit of the Pacific Gardenias and their station, usually near the coast, however, would render this possible.

NOTE 28 (page 52)

THE LITTORAL PLANTS OF THE HAWAIIAN ISLANDS

Column headings:

A: Indigenous. B: By aborigines in ancient times. C: By Europeans soon after discovery. D: Old World. E: New Worlds. F: Both Worlds. G: Large. H: Small. I: Float for months. J: Sink at once or in a few days. K: Attract frugivorous birds.

+---------------------------+---+---+---+---+---+---+---------------------+ | | Origin. | Distri- | Characters of fruit | | | | bution. | or seed. | | +---+---+---+---+---+---+-------+---------+---+ | Species.[5] | |Intro- | | | | Size. |Buoyancy.| | | | |duced. | | | | [6] | | | | | +---+---+ | | +---+---+-----+---+---+ | | A | B | C | D | E | F | G | H | I | J | K | +---------------------------+---+---+---+---+---+---+---+---+-----+---+---+ | Acacia Farnesiana |...|...| + |...|...| + |...| + |weeks|...| ? | | Cæsalpinia Bonducella | + |...|...|...|...| + |...| + | ... | + |...| | Calophyllum inophyllum |...| + |...| + |...|...| + |...| + |...|...| | Cassytha filiformis | + |...|...|...|...| + |...| + | + |...| + | | Colubrina asiatica | + |...|...| + |...|...|...| + | + |...|...| | Cordia subcordata |...| + |...| + |...|...|...| + | + |...|...| |E Cuscuta sandwichiana | + |...|...|...|...|...|...| + | ... | + |...| | Cocos nucifera |...| + |...|...|...| + | + |...| + |...|...| |P Gossypium tomentosum | + |...|...|...|...|...|...| + | ... | + |...| |P Heliotropium anomalum | + |...|...|...|...|...|...| + | ... | + |...| | Heliotropium curassavicum| + |...|...|...|...| + |...| + | ... | + |...| | Herpestis Monnieria | + |...|...|...|...| + |...| + | ... | + |...| | Hibiscus tiliaceus |...| + |...|...|...| + |...| + | + |...|...| | Ipomœa glaberrima | + |...|...| + |...|...|...| + | + |...|...| | Ipomœa pes capræ | + |...|...|...|...| + |...| + | + |...|...| |E Jacquemontia sandwicensis| + |...|...|...|...|...|...| + | ... | + |...| |E Lipochæta integrifolia | + |...|...|...|...|...|...| + | ... | + |...| | Morinda citrifolia |...| + |...| + |...|...|...| + | + |...| ? | | Mucuna gigantea | + |...|...| + |...|...| + |...| + |...|...| | Pandanus odoratissimus |...| + |...| + |...|...| + |...| + |...|...| | Portulaca oleracea |...| + |...|...|...|...|...| + | ... | + |...| | Scævola Kœnigii | + |...|...| + |...| + |...| + | + |...| + | | Sesuvium Portulacastrum | + |...|...|...|...|...|...| + | ... | + |...| | Tacca pinnatifida |...| + |...| + |...| + |...| + | + |...|...| | Tephrosia piscatoria | + |...|...| + |...|...|...| + | ... | + |...| | Terminalia Katappa |...|...| + | + |...|...| + |...| + |...|...| | Thespesia populnea |...| + |...| + |...|...|...| + | + |...|...| | Tribulus cistoides | + |...|...|...| + |...|...| + | ... | + |...| | Vigna lutea | + |...|...|...|...| + |...| + | + |...|...| | Vitex trifolia | + |...|...| + |...|...|...| + | + |...| + | +---------------------------+---+---+---+---+---+---+---+---+-----+---+---+ Footnote 5:

There are three endemic species here included which are preceded by E.
Two species preceded by P are confined to Polynesia. Most of the
plants are at present typically littoral, though often also occurring
inland.

Footnote 6:

All fruits or seeds, an inch or over in size, that could not have been
transported to Hawaii by birds are regarded as large.

NOTE 29 (page 54)

BOTANICAL NOTES ON THE COAST-PLANTS OF THE HAWAIIAN ISLANDS

[The following remarks have been extracted from my journals and represent some of the field-notes of journeys made in the more interesting localities.]

(1) _Walk along the Puna Coast, Hawaii, from Punaluu to Hilo_ (Dec. 26, 1896, to Jan. 6, 1897).—For the first two to three miles to Kamehame Point, the following plants were noticed on the flows of smooth ropy lava that formed the cliff-bound coast—Capparis sandwichiana, Jacquemontia sandwicensis, Ipomœa insularis, Lipochæta lavarum, Portulaca villosa, Tephrosia piscatoria, Tribulus cistoides, Waltheria americana, &c. Beyond this point Scævola Kœnigii was abundant in places on the old lava-flows near the sea, and further on patches of Myoporum sandwicense growing, not as a tree 20 to 30 feet high, as in the mountains, but as a prostrate shrub with fleshy leaves. Vegetation similar to that above described occurred on the surface of the old lava-flows that constituted the cliff-bound sea-border as far as Kapapala Bay. On the sandy beach at Kapapala Bay grew Ipomœa pes capræ, serving as host to Cuscuta sandwichiana. In the vicinity of the house at Keauhou there were a few Coco palms and Pandanus trees, whilst Capparis sandwichiana and Morinda citrifolia were growing on the adjacent lava-fields.

Morinda citrifolia and Tephrosia piscatoria grew on the lava flows between Keauhou and Apua. On the beach at Apua, Ipomœa pes capræ and Scævola Kœnigii were abundant, the last extending a few hundred yards inland on the lava. Further east the inland bush, made up of Cyathodes tameiameiæ, Metrosideros polymorpha, &c., descended to the coast to within a few hundred yards of the sea. In crossing the lava coast plains to Kapa-ahu I observed Morinda citrifolia growing frequently out of the cracks in the bare lava-rock, and an occasional solitary tree of Erythrina monosperma growing also from the fissures.

Before reaching Kapa-ahu we passed the site of an old coast village, named Laepuki, where there were growing from forty to fifty Coco-nut palms, as well as another village, represented by a solitary house, and named Kamomoa, where there were 27 Coco-nut palms and a few Pandanus trees. Kapa-ahu, with its numerous Coco-nut palms, was more like a South Sea coast village than any before seen; and the coast vegetation suddenly acquired a South Pacific character.

At Pulama, for instance, about a mile west of Kapa-ahu, where the ancient lava-flows, fairly vegetated, terminate at the sea in cliffs 20 or 25 feet high, there is a curious and quite unexpected development of a littoral flora such as we should see in the South Pacific. Here, growing on the broken lava surface at the brink of the cliffs and overlooking the sea, thrive Cæsalpinia Bonducella, Cocos nucifera, Ipomœa pes capræ, Ipomœa glaberrima, Morinda citrifolia, Pandanus odoratissimus, Scævola Kœnigii, Sesuvium Portulacastrum, Thespesia populnea, and Vigna lutea. This shore-belt of characteristic littoral plants is backed by vegetation more inland in its character, amongst which Aleurites moluccana, Dodonæa viscosa, Erythrina monosperma, Ipomœa insularis, I. bona nox, Osteomeles anthyllidifolia, &c., are to be observed. Such a shore-belt of typical littoral plants is rarely to be found in the large island of Hawaii; and its usual position at the margin of cliffs, and raised 20 or 25 feet above the sea, is rather suggestive of an uplift in recent times of this part of the coast.

Between Kapa-ahu and Kalapana is a low country occupied mostly by Guavas, and often turfy. At Kalapana, which is a large village situated on a grassy plain by the sea, Coco palms and Pandanus trees abound, and Mucuna gigantea and Cæsalpinia Bonducella are frequent near the coast, whilst Ipomœa pes capræ is common on the beach. Calophyllum inophyllum is planted near the houses. Here Osteomeles anthyllidifolia in its dwarfed form descends to the edge of the cliffs. About half a mile beyond Kalapana is the hamlet of Kaimu, and here among the Coco palms close to the beach I noticed four Loulu palms (Pritchardia Gaudichaudii). Beyond Kaimu the trees and shrubs of the inland wood, Metrosideros polymorpha, Cyathodes tameiameiæ, &c., descend on the spurs of old lava-flows close to the coast; whilst Pandanus and Morinda citrifolia with Mucuna gigantea are common near the sea as far as Kehena, where there are plenty of Coco palms. I approached Opihikao through as fine a Pandanus forest as I have ever seen, the large Bird’s Nest Fern (Asplenium nidus) growing half-way up their trunks, adding picturesqueness to the scene, whilst Mucuna gigantea was a common climber. Beyond Opihikao the inland woods descend to the coast. Thence on to Makuu the coasts are mostly occupied by Pandanus forests, and the lower coast road from Makuu to Hilo traverses a region where these Pandanus trees abound, extending far inland. Scævola Koenigii and Ipomœa pes capræ are common on the coast near Coco-nut Island, Hilo Bay.

It may be added that the agency of the wild goat explains the dispersal of Myoporum sandwicense, Morinda citrifolia, Tephrosia piscatoria, Waltheria americana, &c., over the almost bare surfaces of the lava flows on the Puna coast. Goat droppings were frequent under the patches of Myoporum and Waltheria. In some of them I found the entire seeds of Portulaca oleracea and the small cocci of Euphorbia pilulifera, weeds common in the district.

(2) _Coasts of the Kalae Promontory and its Vicinity, Hawaii._— This is the most southerly portion of the group, and it is on the eastern coasts of this district that many of the North American drift logs are embayed and stranded. At Kamilo, to the east of the promontory, there is a long beach of calcareous sand where Heliotropium anomalum, Scævola Kœnigii, and Tribulus cistoides grow in abundance, whilst Sesuvium Portulacastrum thrives on the beach and in brackish pools. Portulaca lutea (Sol.), Ipomœa glaberrima (Boj.), and Jacquemontia sandwicensis also occur. Where the beach-sand has encroached on the adjacent lava surface, the Scævola covers extensive tracts off the beach, and is stunted. I noticed a solitary thicket of Thespesia populnea on the beach.

The actual headland of Kalae is wind-swept and covered with grass, amongst which Portulaca villosa and Sida fallax thrive. By the sea occur Scævola Kœnigii and Ipomœa pes capræ, and there is some Sesbania tomentosa near the point. Waiheiaukini beach is shut in between the lofty arid slopes of the promontory on one side and a modern lava-flow on the other side. Here Scævola Kœnigii grows in quantity, together with Ipomœa pes capræ, Tribulus cistoides, Sida fallax, and Jacquemontia sandwicensis, whilst Cuscuta sandwichiana is abundant, finding its hosts in the first four plants just named.

(3) _South Kona Coast, Hawaii._—The coast here, as exemplified by that between Kapua and Hoopuloa, is mostly bare lava. Here and there, a little coral sand collects amongst the lava blocks of the rubbly shore, and it is in such places that Scævola Kœnigii and Ipomœa pes capræ find a home and apparently thrive, whilst Hibiscus tiliaceus and Morinda citrifolia grow behind. I observed Cordia subcordata and one or two specimens of Pritchardia Gaudichaudii by the coast on the south side of Milolii. Around a brackish pool at Kapua I observed Heliotropium curassavicum, and Acacia Farnesiana was to be seen growing on the beach at Okoe. On the lava coast between Hoopuloa and Papa, two miles to the north, Tephrosia piscatoria was very abundant.

(4) _North Kona Coast, Hawaii._—I examined the coast between Kailua and Kiholo. White beaches are common south of Keahole Point, the coast further north being usually lava-bound with sandy beaches here and there. Heliotropium anomalum, Ipomœa pes capræ, and Sesuvium Portulacastrum are the commonest beach plants on this coast. Scævola Kœnigii is also abundant in places, whilst Tribulus cistoides and Morinda citrifolia are also fairly common on the beaches. The Morinda also grows on the adjacent lava flats; but on both sand and rock it is evidently usually self-sown, since seedlings are to be seen near the older plants. Heliotropium curassavicum is to be seen here and there on the sand all along the coast, but nearly always associated with H. anomalum. Jacquemontia sandwicensis occurs occasionally on the beach; and Cuscuta sandwichiana is abundant in places, growing generally on Ipomœa pes capræ, but sometimes on Scævola Kœnigii. Brackish water ponds are common on the coast inside the beaches, Ruppia maritima flourishing in the water, with Sesuvium Portulacastrum growing at the edges. Sometimes Hala trees (Pandanus odoratissimus) fringe the borders of the pools. I noticed Pritchardia Gaudichaudii on the coast at Kiholo, and I learned that Cordia subcordata was once common here as on other parts of the Kona coast; but it has died out as in most other localities.

(5) _Kohala Coast, Hawaii._—Several littoral plants are scantily represented on the beach of black sand at the mouth of the Waimanu valley, especially Ipomœa pes capræ, Morinda citrifolia, Pandanus odoratissimus, and Scævola Kœnigii. The Pandanus covers the adjacent precipitous slopes up to a height of several hundred feet above the sea. Ipomœa pes capræ is abundant on the sand dunes backing the beach at Waipio. I observed Naias marina in the Waipio River just inside the mouth. No one seems to have recorded the plant from the group since Chamisso found it in Oahu.

(6) _Hamakua Coast, Hawaii._—Not many opportunities presented themselves on this cliff-bound coast of finding littoral plants. At the mouth of a gulch between Ookala and Laupahoehoe I found growing at the coast Vitex trifolia (var. unifoliolata) in quantity, together with Morinda citrifolia, Scævola Kœnigii, and Pandanus odoratissimus, the last-named clothing the hill-slopes overlooking the sea.

(7) _The Coasts of Oahu._—The littoral vegetation of the south-east portion of the island from Diamond Head round to Waimanalo is, as a rule, scanty. Ipomœa pes capræ and Tribulus cistoides prevail to Koko Head, and on the rubbly coast between that headland and Makapuu Point occur Tephrosia piscatoria, different species of Lipochæta, &c. Between Makapuu Point and Waimanalo, Scævola Kœnigii and Vitex trifolia (var. unifoliolata) are fairly abundant, the former growing on the rocky slope at the base of the cliffs, and raised perhaps some 20 feet above the sea. Along the whole east coast of the island the littoral vegetation is rarely well represented. However, Ipomœa pes capræ is common everywhere, whilst Scævola Kœnigii occurs frequently, and here and there a few plants of Morinda citrifolia are seen on the beach, while thickets of Hibiscus tiliaceus mark in some localities the mouths of streams.

On the north coast of Oahu, as on the Waialua and Waimea beaches, the one-leaved variety of Vitex trifolia is common, together with Ipomœa pes capræ and Euphorbia cordata; whilst Acacia Farnesiana is frequent on the Waialua beach, its pods being much appreciated by the cattle. Occasionally, as by the bridge at Waimea, Colubrina asiatica and Thespesia populnea are to be noticed.

Shore vegetation is a little better represented on the beaches at and near Kaena Point, the north-west corner of the island. Here on the sand we find often in abundance Heliotropium anomalum, the same variety of Vitex trifolia, Scævola Kœnigii, and Ipomœa pes capræ; whilst on the rocks bordering the beach occur Gossypium tomentosum, Jacquemontia sandwicensis, Tribulus cistoides, Vigna lutea, and more than one species of Lipochæta, the last being derivatives from the inland flora.

On the west coast of the island true shore-plants play an inconspicuous part. Ipomœa pes capræ is common on the beaches, and such plants as Acacia Farnesiana, Jacquemontia sandwicensis, Gossypium tomentosum, and Tribulus cistoides immediately border the beach. Ipomœa tuberculata is a frequent intruder as well as the recently introduced Algaroba tree (Prosopis dulcis). Acacia Farnesiana also extends inland, covering entire large areas and forming in the Waianae valley extensive thickets impenetrable for the cattle. It occupies great districts near the coast in different parts of Oahu, and with Hibiscus tiliaceus is to be found far inland. The cattle are active dispersers of its seeds. (See Note 30.)

True beach plants are infrequent at the mouth of Pearl Harbour, although the coast is well suited for them. Here I found Heliotropium anomalum, H. curassavicum, Jacquemontia sandwicensis, Lipochæta integrifolia (a true beach plant), Herpestis Monnieria, &c. Batis maritima occurs in one or two localities around Oahu, but it is, according to Hillebrand, of recent introduction.

NOTE 30 (page 58)

THE BEACH-DRIFT OF THE HAWAIIAN ISLANDS

It was pointed out by Dole long ago in one of the Hawaiian Club Papers (1868) that the existing currents bring to this archipelago only huge pine logs from Oregon, but no tropical fruits; and Hillebrand (p. xiv.) refers to the driftwood of pine logs from the north-west coast of America, stranded on the shores of these islands. This drift seems to collect in quantity in particular localities, as on the south-east coast of Hawaii between Honuapo and the Kalae promontory (especially on the Kamilo beach near Kaluwalu) and on the east coast of Oahu; and probably there are other favourable localities for catching the drift on the northern shores of Maui and Molokai.

It was on the south-east coast of Hawaii (on the beach at Kamilo and on the eastern side of the Kalae promontory) that this drift came particularly under my notice. Here the logs are stranded in abundance, in sufficient quantity, in fact, to build a town, and they were employed for building purposes by the manager of the neighbouring sugar-cane plantation. Several of the logs are of huge size, as much as 4 feet in diameter; and they are known locally as “white cedar” and “red cedar,” and characterised as Oregon timber. Some of them are extensively burrowed by the “teredo” and other boring mollusks. Others recently stranded are covered with barnacles (Lepadidæ), whilst others that have lain long on the beach are bare. I have seen these logs occasionally washed up at Punaluu and at different places on the lava-bound Puna coast. They apparently first strike the Puna coast, and are drifted along until they become embayed near the Kalae promontory, and ultimately stranded. Mingled with them on the beaches Pandanus trunks occur in number; they evidently hail from those parts of the Puna coast where Pandanus forests prevail, and thus they indicate the direction of the drift on the coast of this island. In places there was a considerable amount of small vegetable _débris_, sometimes partially concealed by the sand, and containing seeds and fruits in fair quantity.

The following seeds and fruits were collected:—

_Pandanus_ drupes, common; most of them fresh-looking, but a few much worn. _Thespesia populnea_, a few seeds. _Ipomœa pes capræ_, seeds, fair numbers. _Ipomœa bona nox_, seeds, a few. _Ipomœa glaberrima_, seeds, a few. _Argyreia tiliæfolia_, fruits and seeds, a few. _Strongylodon lucidum_, seeds, a few. _Cæsalpinia Bonducella_, a single seed. _Vigna lutea_, seeds, a few. _Calophyllum inophyllum_, a few fruits. _Ricinus communis_, a few, the seeds either free or in the cocci, and often empty or decaying. _Aleurites moluccana_, seeds, common, none sound, either empty or containing a rotten kernel: also a single fruit. One or two seeds not identified.

There was seemingly a total absence of the fruits or seeds of any littoral plant not found in these islands, such as I was familiar with in the South Pacific. In the mass this seed-drift could have been derived from the neighbouring coasts of the island. This is especially indicated in the cases of the fruits and seeds of Aleurites moluccana, Ricinus communis, and Argyreia tiliæfolia. The sound seeds of Aleurites do not float, the buoyant seeds being always empty, or nearly so; and the presence of the seeds in beach-drift, as explained on page 419, is due partly to the buoyancy of the empty seed and partly to the decay of the stranded fruit, the fruits being able to float for a week or two. So, also, the seeds of Ricinus, whether free or inclosed in the coccus, do not, when sound, float longer than a week or ten days. The capsules of the Argyreia can float two or three weeks, whilst the seeds vary in their behaviour, as observed on page 20. I noticed in places where the vegetable _débris_ was heaped up and exposed to the sun’s heat, that some of the Ipomœa seeds were germinating. It is to be remarked that horse-dung and goat-dung are always common in the beach-drift of these islands. Seeds are sometimes to be seen in the stranded material; and it was evident that the droppings of these animals can float for some weeks before breaking down.... I may add that large sponges, apparently of no value, are thrown up in quantities on the east side of the Kalae promontory.

Excepting the pine logs, the only things coming under my notice in this beach-drift that could be characterised without hesitation as non-Hawaiian, were two well-worn pieces of acid pumice, less than an inch in size. One of them was incrusted partially by the tubes of annelids, and both of them had evidently been drifting about in the Pacific for a long period, perhaps for years. They were such as occur in abundance on the beaches of the South Pacific, and, in fact, on all the shores of the Pacific Ocean, both temperate and tropical. Although I carefully searched the stranded drift of many beaches in this group, no other specimens of drift pumice were found.

On different parts of Oahu the beach-drift was always made up of materials derived from the vegetation of the coast adjacent. Of most frequent occurrence were the seeds of Ipomœa pes capræ and Vigna lutea, and the fruits of Scævola Kœnigii, Vitex trifolia, and Pandanus odoratissimus. In addition, the empty seeds of Aleurites moluccana were numerous, and there were occasional seeds of Thespesia populnea, Colubrina asiatica, and Mucuna gigantea. On one beach there were a number of fruits of Terminalia Katappa, showing but little signs of ocean travel, and evidently derived from trees in the vicinity. This tree was introduced by Europeans; but it is not unlikely that in a generation or two it will become, without man’s aid, one of the characteristic beach trees of Oahu. It may be remarked that the pods of Acacia Farnesiana, a shrub now growing abundantly in Oahu near the sea, are washed up in great quantities on the beaches of the west coast of this island, and the seeds are to be seen germinating in numbers on the beach, the seedlings striking into the sand. The pods float unharmed in sea-water for four or five weeks, but the seeds, when freed, sink.

Although the above evidence gives no indication of tropical drift of non-Hawaiian origin on the beaches, it is probable, for reasons adduced in Chapter VIII., that, in the winter, drift may be brought from tropical America.

NOTE 31 (page 59)

THE INLAND EXTENSION OF THE SHORE-PLANTS OF HAWAII

_Cæsalpinia Bonducella._—According to Hillebrand, this plant, so characteristic of the littoral floras of tropical regions, grows “in gulches of the lower plains on all the islands,” no reference being made to its occurrence on the beaches. It is very rarely to be seen on the beaches of the large island of Hawaii; but it is to be found on the lava-bound coasts, and from there it extends inland usually on old lava-flows for five or six miles, and reaches sometimes considerable elevations. In one locality I found it at 2,000 feet above the sea (see page 188).

_Cassytha filiformis._—Though a typical shore-plant in Fiji and other tropical localities, it is rarely so in these islands. Hillebrand says nothing of its station. It grows well in the lower open wooded regions, and is frequently found amongst the blocks of old lava-flows near the coast.

_Cuscuta sandwichiana._—Unlike its fellow parasite Cassytha filiformis, this species of Cuscuta, which is confined to this group, never came under my notice away from the beach; and Hillebrand speaks of finding it only at the coast (see page 366).

_Ipomœa pes capræ_, as I observed it in the islands of Hawaii and Oahu, is confined to the beach or to neighbouring sand-dunes. Hillebrand makes no reference to its occurrence inland. This species in these islands offers thus a great contrast to its behaviour in Fiji.

_Scævola Kœnigii._—Whilst most at home on the sandy beaches, this plant is also frequently met with in the island of Hawaii on scantily vegetated lava-flows near the coast; but I never noticed it more than a few hundred yards from the sea.

_Tephrosia piscatoria._—Though it may occur on the beach, it is generally found as described by Hillebrand on the rocky or rubbly ground at the back of the beach, as well as further inland. It is common on the old lava-fields of the island of Hawaii near the coast; and, according to the natives, its seeds are disseminated by the wild goats that frequent these localities.

_Tribulus cistoides._—Hillebrand observes that this plant is found along the sea-shore and on the lower plains. I found it most frequently on the beaches and on the old lava-flows near the sea.

_Vitex trifolia, var. unifoliolata._—It is confined, as Hillebrand remarks, to the beaches. Neither in Oahu nor in Hawaii did I ever find it straying inland, which is the more remarkable since this variety, or one closely similar to it, is one of the most characteristic inland plants of the Fijian strand-flora.

_Vigna lutea._—This plant was found by me growing on the beaches and in their vicinity. Hillebrand merely speaks of it as “growing at short distances from the shore.”