Observations of a Naturalist in the Pacific Between 1896 and 1899, Volume 2 / Plant-Dispersal

by H. B. Guppy

Cæsalpinia in Fiji, Tahiti, and Hawaii.

Locality.			Species.	Foliaceous stipules.	Pairs of pinnæ.	Leaflets			Seeds
						Pairs.	Length in inches.	Form.	Size in tenths of inch.	Colour
Coast, Fiji			Bonducella	Present	8-9	9-11	11⁄4-11⁄2	Oblong, obtuse mucronate: base rounded and in—equilateral	61⁄2-71⁄2	Usually lead-colour with at times brownish-yellow patches.
			Bonduc	Absent	5-6	4-6	21⁄2-5	Oblong, acuminate mucronate, base rounded or subcordate	51⁄2-6	Pale yellow
									61⁄2-71⁄2	Pale grey, sometimes mixed with yellow.
			Intermediate	Present	7-8	7-9	2-3	Oblong, obtuse mucronate,rounded at base; upper leaflets may be elliptical	6-7	Lead-colour or pale grey with brownish-yellow patches
Inland, Fiji			Mountain species	Present	5-6	9-10	11⁄2-23⁄4	Lanceolate with long tapering aristate apex and rounded base	6	Yellowish or pale grey or mixed.
Coast, Tahiti			Bonducella	Present			1⁄2-14⁄5	Oblong
Inland, Tahiti			Bonduc	Absent		5-6		Oblong
Inland, Hawaii			Bonducella		4-6	6-8	14⁄5-2	Oblong, obtuse, not cordate at base	6-7	Lead-colour.

Locality.			Species.	Foliaceous stipules.	Pairs of pinnæ.	Leaflets
						Pairs.	Length in inches.	Form.
Coast, Fiji			Bonducella	Present	8-9	9-11	11⁄4-11⁄2	Oblong, obtuse mucronate: base rounded and in—equilateral
			Bonduc	Absent	5-6	4-6	21⁄2-5	Oblong, acuminate mucronate, base rounded or subcordate
			Intermediate	Present	7-8	7-9	2-3	Oblong, obtuse mucronate,rounded at base; upper leaflets may be elliptical
Inland, Fiji			Mountain species	Present	5-6	9-10	11⁄2-23⁄4	Lanceolate with long tapering aristate apex and rounded base
Coast, Tahiti			Bonducella	Present			1⁄2-14⁄5	Oblong
Inland, Tahiti			Bonduc	Absent		5-6		Oblong
Inland, Hawaii			Bonducella		4-6	6-8	14⁄5-2	Oblong, obtuse, not cordate at base

Locality.			Species.	Foliaceous stipules.	Pairs of pinnæ.	Seeds
						Size in tenths of inch.	Colour
Coast, Fiji			Bonducella	Present	8-9	61⁄2-71⁄2	Usually lead-colour with at times brownish-yellow patches.
			Bonduc	Absent	5-6	51⁄2-6	Pale yellow
						61⁄2-71⁄2	Pale grey, sometimes mixed with yellow.
			Intermediate	Present	7-8	6-7	Lead-colour or pale grey with brownish-yellow patches
Inland, Fiji			Mountain species	Present	5-6	6	Yellowish or pale grey or mixed.
Coast, Tahiti			Bonducella	Present
Inland, Tahiti			Bonduc	Absent
Inland, Hawaii			Bonducella		4-6	6-7	Lead-colour.

Note.—The characters of the Fijian plants are from my own observations. Drake del Castillo is quoted for Tahiti, and Hillebrand for Hawaii. Reinecke observes that the pods of C. bonducella in the inland forests have no prickles.

In Fiji all three coast forms may be found on the same beach, or they may exist apart. The large-leaved species (C. bonduc) appears to be much the most frequent in Vanua Levu; and the intermediate form is common enough to disturb the serenity of the observer’s mind when he is anxious to diagnose rather than to collect cumbersome specimens. The mountain form, which came under my notice as a climber in the forest at an elevation of 1,700 feet on the slopes of Koro-mbasanga in Vanua Levu, acquires from the lanceolate shape of its leaflets quite a character of its own, though it comes nearest to Cæsalpinia bonducella. Mountain forms also occur, as indicated in a later page, in the forests of Samoa and in Tahiti; but in the first-named group they are referred by Reinecke to C. bonducella, and in Tahiti by Drake del Castillo to C. bonduc. In the Samoan forests the inland plants possess pods deprived of the prickles that are so characteristic of the beach plants. Before one can pronounce definitely on the relation between the coast and inland forms in any of the groups, a thorough investigation of the connections between the two shore-species is needed. I am inclined to think that they will prove to belong to a single dimorphic (or perhaps polymorphic) species.

The distribution of Cæsalpinia bonducella and C. bonduc.—Botanists agree in giving C. bonducella a distribution around the tropics of the globe; but they are not at all unanimous with respect to the other species. According to Mr. Hemsley this species is by no means so universally dispersed as C. bonducella. It is unknown from Africa and Australia; but it is generally characteristic of tropical Asia and the Malay Archipelago. The same authority alludes to specimens in the Kew Herbarium from Florida and the West Indies (Bot. Chall. iv, 300). Drake del Castillo gives both species a range through the tropics, whilst Schimper seems in doubt about the occurrence of C. bonduc in the New World, and Mr. Burkill makes no allusion to its American habitat in his paper on the Tongan flora. The cause of this confusion is doubtless to be mainly attributed to the variation in characters of the plants, and to the occurrence of intermediate forms.

We should be scarcely consistent if we assumed that of two kindred shore-species dispersed by the currents one had its home in America and the other in the Old World. The same home must belong to both. According to the principle laid down in [Chapter VIII], and referred to under Entada scandens, it is held that a strand-plant, with its home in Asia, on account of the arrangement of the currents could never reach the American continent, and that American shore-plants are for the most part native-born except those hailing from the African West Coast, which, however, lies within the American province of tropical strand-plants. From this standpoint Cæsalpinia bonducella would be regarded as now having its home in the New World, and since it is found on both the Pacific and Atlantic coasts of that continent (as well as on both coasts of Africa), it is assumed, as with Entada scandens, that it has reached the African West Coast by crossing the Atlantic, and the African East Coast by way of the Pacific and Indian Oceans. The genus, I may remark, is distributed over the tropics of the eastern and western hemispheres.

As regards the general distribution of the two species in the Pacific islands, it would appear from the writings of Seemann, Hillebrand, Hemsley, Drake del Castillo, Reinecke, Cheeseman, and Burkill that with the exception of Hawaii and Samoa, where Cæsalpinia bonducella alone occurs, and of Rarotonga where C. bonduc alone is found, they are generally associated in the larger groups, as in Fiji, Tonga, Tahiti, and the Marquesas.

The station of Cæsalpinia bonducella and C. bonduc.—Both the species are to be regarded as littoral plants likely to stray inland. The first-named is described in the Botany of the “Challenger” Expedition as essentially a sea-side plant, though flourishing equally well inland, and in India extending to the Himalayas as far as Kumaon, and up to elevations of 2,500 feet. Schimper speaks of both species as characteristic of the Indo-Malayan strand-flora, and he quotes Kurz when referring to C. bonduc as a constituent of the beach-jungle of Pegu.