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Dioclea wilsonii Standl. [ Fabaceae ]

Taxonomy Reports: ITIS | IPNI | IOPI

Samoan Name:
English Name:
Status: Indigenous
Habit: Vine

Whistler 10516

Whistler 11502

Indigenous to American Samoa, ranging from Central America and Hawai‘i to Fiji. In Samoa, it is restricted to a single mountaintop on Tutuila, Mt. Tau, where it occurs in montane scrub, reported only from 350 m elevation. It is widespread but rare elsewhere in Polynesia (Hawai‘i, Tahiti, and the Austral Islands) and possibly Fiji (“Dioclea sp.”). It may have originally been native to coastal forests in Honduras, if this is the same species, but has apparently spread long distances by means of its hard, seawater-resistant seeds. There is no plausible explanation as to how this vine got to the Mt. Tau summit and no place else in the archipelago. Further taxonomic work needs to be done on this species since it is unlikely that the same one occurs in both Honduras and Polynesia. This plant was recommended for a threatened or endangered status because it is very rare in Samoa (a single known locality) and the Pacific Islands. No uses or Samoan names have been reported for this species.

Liana, climbing or trailing, with pubescent stems and lanceolate, weakly peltate, subpersistent stipules ca. 9–12 mm long. Leaves trifoliate, alternate, rachis 7–10 cm long, pubescent, with a pubescent pulvinus at the base, leaflets elliptic, 7–12 cm long, rounded at the base, shortly acuminate at the tip; surfaces glabrous, upper side darker, lower side with pubescent veins; margins entire; stipules. Inflorescence an axillary, narrow, raceme-like panicle 20–50 cm long, with upcurved, short, thick flowering branches 3–5 mm long. Calyx campanulate, 1–1.4 cm long, divided halfway into 5 unequal lobes, subsessile. Corolla papilionaceous, dark purple; banner long-clawed, broadly ovate, ca. 1.3–1.5 cm long; wings long-clawed, unequally obovate, ca. 1.2–1.4 cm long; keel bent to nearly a right angle, ca. 1 cm long. Ovary superior, style thickened with a small capitate stigma. Stamens 10, diadelphous, with 9 fused together at the base, enclosed within the keel, only half of the anthers fertile. Fruit (not known from Samoa) a glabrescent. oblong pod 7–13 cm long, with 2 or 3 lens-shaped seeds 1.8–2 cm in diameter, these with an oblong hilum over half the diameter of the seed.

Distinguishable by its viney habit; alternate, trifoliate leaves; ovate leaflets; raceme-like panicles with flowers borne on short stalks; dark purple papilionaceous flowers with a yellow blotch in the center; and a legume fruit (not seen).

TUTUILA:
110. Whistler 10516—On top of Mt. Tau just west of the beacon.
111. Whistler 11502—On top of Mt. Tau just west of the beacon.

Other Collections:

Georeference: -14.315569, -170.701986

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