[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.”

Some of the trees, usually littoral in their station in the tropical Pacific, which are regarded as having been introduced in early times into the Hawaiian group by the Aborigines (see Chapter VII.), behave, nevertheless, quite like indigenous plants in the inland regions and in the lower levels. This is true, for instance, of Hibiscus tiliaceus and Pandanus odoratissimus, the last-named forming forests at the sea-board extending in places far up the mountain slopes. The same, however, may be said of other plants known to have been introduced since the discovery of the islands, as in the cases of Cactus Tuna and of Ricinus communis; and it also applies to Aleurites moluccana, the Candle-nut Tree, which, although it could only have been introduced by the Aborigines, now forms forests on the lower slopes of the mountains.

NOTE 32 (pages 19, 112, 165)
 
The Fijian Species of Premna

I was much interested in the small trees and shrubs of this genus in Fiji, more especially on account of the relation between the shore and inland species. This is an Old World genus containing some eighty species mainly characteristic of tropical Asia and Malaya, and represented in the South Pacific archipelagoes by two species, one Premna taitensis or tahitensis, spread over the region and very near P. integrifolia, an Asiatic species; the other Premna serratifolia, an Asiatic plant found in Fiji, the Marquesas, and other groups. Without endeavouring to give a precise value to the Fijian plants, I will merely describe the prevailing forms, which are, however, connected by intermediate varieties. These trees, I may add, are known by the same name in the various Pacific groups, “Avaro” or “Avalo” in Tahiti, “Alo-alo” in Samoa, “Yaro” and “Yaro-yaro” in Fiji.

The Fijian plants may be thus described.... (a) Premna serratifolia, an inland tree, growing in open woods and on the outskirts of the forest, 25 to 30 feet high, more or less hairy, leaves coarsely serrated with long tapering points, putamen prominently tuberculated and thick-walled.

(b) Premna taitensis or P. integrifolia, a low straggling coast tree or shrub of the beaches, the coral islets, the swampy borders of the estuaries, and the inland talasinga plains, its usual height being eight to ten feet, except in the inland plains, where it is dwarfed, and three to five feet high. It is more or less glabrous, the leaves being typically entire with obtuse or retuse and mucronate apices. The putamen is thin-walled and relatively smooth. (c) Intermediate forms found generally in the inland plains or talasinga regions.

On the Modes of Dispersal.—Speaking generally, the small drupes of both species float at first, but the soft parts are soon removed by decay, and the stone is freed. In the case of the coast species, P. taitensis, the stones float indefinitely and are often found afloat in rivers. In the case of the inland tree, P. serratifolia, most of the stones sink at once, whilst the others sink in a few days. It is probable that currents are one of the effective agencies in distributing the coast species, but this could not apply to the inland tree. The fruits of both the inland and the coast species would attract birds, and the stones would resist injury in their crops. This is the agency advocated by Prof. Schimper for the shore species, P. integrifolia, of Indo-Malaya; and fruits referred with a query to this genus were found in the collection of seeds and fruits obtained by me from the crops of pigeons in the Solomon Islands (Bot. Chall. Exped., Introd. p. 46, part IV. p. 312).

On the Cause of the Buoyancy of the Stone or Putamen of the Coast Species.—This is primarily connected with the empty seed-cavities, the four-celled stone usually developing only one seed, the other cavities being empty. This inference was established by the dissection of a large number of stones, but it will be seen from the table below that one-seeded stones are also frequent in the case of the inland tree (P. serratifolia), where they as a rule sink. With either species the substance of the stone has no floating power, but with the shore species, on account of the thin-walled stone, the empty seed-cavities cause it to be specifically lighter than water whilst with the inland species the walls of the stone are so thick that the empty spaces of the unfilled seed-cavities do not effect the same result. It may be remarked that when the coast species grows in the inland plains the buoyancy of the stone is preserved.

NOTE 33 (page 63)
 
De Candolle’s List of Plants dispersed exclusively by Currents

Drepanocarpus lunatus; Ecastaphyllum Brownei; Mucuna urens, D.C.; Tephrosia piscatoria; Hibiscus tiliaceus; Rhizophora mangle; Guilandina Bonduc, Linn.; Ipomœa pes capræ; Canavalia obtusifolia.

I have experimented on the buoyancy of the fruits and seeds of all these plants excepting the two first named. In five species the seeds float in sea-water unharmed for several months. With Rhizophora it is the floating seedling that disperses the plant. Neither the pods nor the seeds of Tephrosia piscatoria are suited for dispersal by the currents.

NOTE 34 (page 64)
 
The Littoral Plants of the Easternmost Polynesian Islands

Except in the case of Hernandia peltata my authority here is the Botany of the “Challenger” Expedition. Mr. J. H. Maiden gives some further details of the flora of Pitcairn Island in a more recent paper (Austral. Assoc. Rep., Melbourne, 1901, vol. 8), and Hernandia peltata is included in his list.

NOTE 35 (page 68)
 
Distribution of the Littoral Plants with Buoyant Seeds or Fruits that are found in the Fijian, Tongan, Samoan, Tahitian, and Hawaiian Groups

This list probably contains nearly all the species of the Polynesian region, but it is not implied that these plants have been recorded from all the groups (vide infra).

(a) Species found only in the Old World.—Calophyllum inophyllum, Hibiscus diversifolius, Thespesia populnea, Heritiera littoralis, Kleinhovia hospita, Carapa moluccensis, C. obovata, Smythea pacifica, Colubrina asiatica, Mucuna gigantea, Erythrina indica, Strongylodon lucidum, Dalbergia monosperma, Pongamia glabra, Inocarpus edulis, Derris uliginosa, Afzelia bijuga, Barringtonia racemosa, B. speciosa, Rhizophora mucronata, Bruguiera Rheedii, Terminalia Katappa, T. littoralis, Lumnitzera coccinea, Pemphis acidula, Morinda citrifolia, Guettarda speciosa, Wedelia biflora, Scævola Kœnigii, Cerbera Odollam, Ochrosia parviflora, Cordia subcordata, Tournefortia argentea, Ipomœa glaberrima, I. grandiflora, I. peltata, Aniseia uniflora, Clerodendron inerme, Vitex trifolia, Hernandia peltata, Excæcaria Agallocha, Tacca pinnatifida, Cycas circinalis, Pandanus odoratissimus, Scirpodendron costatum.

(b) Species occurring in both the Old and New Worlds.—Hibiscus tiliaceus, Suriana maritima, Ximenia americana, Dodonæa viscosa, Canavalia obtusifolia, C. ensiformis, Vigna lutea, Sophora tomentosa, Cæsalpinia Bonduc, C. Bonducella, Entada scandens, Gyrocarpus Jacquini, Luffa insularum, Ipomœa pes capræ, Cassytha filiformis, Cocos nucifera.

(c) Species occurring in America to the exclusion of the Old World.—Dioclea violacea, Mucuna urens, Rhizophora mangle.

(d) Species found only in Polynesia.—Canavalia sericea, Mucuna platyphylla(?), Cynometra grandiflora, Serianthes myriadenia, Parinarium laurinum(?), Premna tahitensis.

Remarks.—Of these seventy plants there is not one that has not come within the scope of my observations and experiments. The West Coast of Africa is included in the American region for reasons given in Chapter VIII. For the other authorities on the buoyancy of these seeds and fruits reference should be made to the list given under Note 2 and to other parts of this work. About one or two of the plants, like Ipomœa peltata, one scarcely knows whether they are most characteristic of the coast-flora or of the inland-flora.

NOTE 36 (page 72)
 
Hawaiian Plants with Buoyant Seeds and Fruits known to be dispersed by the Currents either exclusively or, as in a few Species, with the Assistance of Frugivorous Birds

Colubrina asiatica.—Usually regarded as confined to the Old World; but since nearly all the species are American, that continent may be considered as the probable home also of this species. Hillebrand gives it a locality in the West Indies.

Dioclea violacea.—Tropical America.

Mucuna gigantea.—Old World.

Mucuna urens.—America, and extending to the African West Coast, which is to be included in the American region of shore-plants.

Strongylodon lucidum.—Old World.

Vigna lutea.—Old and New Worlds.

Cæsalpinia Bonducella.—Old and New Worlds.

Scævola Kœnigii.—Usually regarded as confined to the Old World, but according to the synonymy accepted by some authors it is also to be ascribed to America. The genus is chiefly Australian, and it is possible that the littoral species may have reached America through the agency of birds, since all the species of the genus possess fruits that would attract frugivorous birds.

Ipomœa glaberrima (Boj.).—Old World.

Ipomœa pes capræ.—Old and New Worlds.

Vitex trifolia.—Old World. The genus is also dispersed by pigeons.

Cassytha filiformis.—Old and New Worlds. Like Scævola the genus is chiefly Australian, and here, also, the fruits of the littoral species are not only dispersed by the currents, but are known to be also disseminated by fruit-pigeons.

It is possible that birds may have taken a predominant part in the dispersal of the species of Scævola, Vitex and Cassytha.

There thus remain nine species for consideration. Of these two are exclusively American, three are found in both the Old and New Worlds and four are usually regarded as exclusively Old World plants, but one of them (Colubrina asiatica) has a fair claim to be regarded as of American origin. Thus it is quite possible that six out of these nine plants were brought to Hawaii from America through the agency of the currents.

NOTE 37 (page 78)
 
On Vivipary in the Fruits of Barringtonia racemosa and Carapa obovata

As observed by me in the Rewa delta, Fiji, there was no external evidence of such a process in the case of the fruits on the trees; but I did not pay very special attention to the matter, and it will be gathered from Chapter XXX. that the initial stage of germination may show no indication in the appearance of the fruit. More observation is needed for both species. As indicated in Note 50, the structure of the seed of Barringtonia racemosa is suggestive of a lost viviparous habit. With regard to Carapa, Schimper (p. 43) remarks that he has never observed vivipary; but Miquel, in his Flora Indiæ Bataviæ, particularly speaks of the seeds germinating in the capsule. I think this is very likely, and that perhaps even the rupture of the capsule may be partly due to this cause.

NOTE 38 (page 78)
 
On the Temperature and Density of the Surface-water of the Estuaries of the Rewa River in Fiji, and of the Guayaquil River in Ecuador

(a) The Rewa Estuary.—My observations were made mostly in the warm, wet seasons, from October to January, 1897-99, and generally in the vicinity of the Roman Catholic Mission. The density varied usually between 1·000 and 1·010, the water being quite fresh after heavy rains inland. Though the density was usually greatest at high water, this was by no means always the case. The temperature of the water in dry weather varied from 79° to 84° F. With the river in flood after heavy rains it fell to 75° and 76°. As a rule, the fresher the water the lower the temperature, but this was not invariable. There was evidence of super-heating in the estuary, the water there having sometimes a temperature of 82° or 83°, when the water higher up the river as far as Viria was two or three degrees cooler, the sea-temperature being 79° to 80°. The average temperature of the water of the estuary during the season would be 80 to 81°.

(b) The Estuary of the Rio Guayas, also known, as the Guayaquil River.—My observations were made in the last week of February and in the first half of March, 1904. Whilst the sea-temperature a few miles off the Ecuador coast varied from 76° to 80° F., the water of the estuary from the mouth up to Guayaquil ranged from 79° to 86°, whilst rather higher up the river the temperature was about 79° or 80°. The super-heating of the estuary is thus directly indicated. It was well marked in the lower part of the estuary during one of my ascents of the river.