Osmoxylon truncatum (Kaneh.) Fosberg & Sachet, 1980

Costion, Craig M. & Plunkett, Gregory M., 2016, A revision of the genus Osmoxylon (Araliaceae) in Palau, including two new species, PhytoKeys 58, pp. 49-64 : 54

Osmoxylon truncatum (Kaneh.) Fosberg & Sachet Fig. 3

Boerlagiodendron truncatum Kaneh., Bot. Mag. Tokyo, 48: 403, fig. 2, 1934.

Osmoxylon oliveri Fosberg & Sachet, Smithsonian Contr. Bot. 45: 16. 1980.

Osmoxylon truncatum Type. Palau. Ngardmau: near Dudui’s homestead, 2 Apr 1966 (fr.,fl.), Cheatham 54 (holotype: US!; isotype: NY!, BISH!).

Type.

Palau. Aimeliik State: 2 Aug 1933, R. Kanehira 2364 (holotype FU!; isotype: NY!).

Description.

Small to medium-sized understory tree, 10-20 m tall, branched. Leaf blades palmately lobed and large, up to 80 cm long and 85 cm wide, glabrous, generally with 11-15 lobes, strongly serrated; serrations protruding from margin, 2 or 3 in between each prominent secondary vein; prominent secondary veins meeting the mid-rib at a sharp 45°angle; petioles up to 1.2 meters long, petiolar crests 3 or 4, circular, ciliate; stipule appressed to stem, shallowly furrowed on top with 1-3 ciliate crests resembling horizontal lines of teeth or wart-like projections; margin of stipule papery and tannish, expanding in towards the center as the stipule matures. Compound inflorescences 20-30 cm in diameter, primary axis bearing 20-40 secondary inflorescence units, secondary axis (from primary axis to where lateral umbels are attached) 3-6 cm long, supporting an umbel of 20-30 dark purple to blackish baccate pseudo-fruits up to 1 cm in diameter; peduncles jointed, purple, 5-7 cm long, with bottom segment 2-6 times shorter but becoming longer with maturity. Flowers 45-80 per head with yellow, angular, bright yellow calyx crowning the ovary; corolla tube bright reddish-orange, 5-lobed, 4 mm long; stamens alternate to the petal lobes, strongly exserted; ovary inferior with sessile stigma. Fruits pedicelate, obpyramidal, resembling corn kernels, each c. 1 cm long, 1 cm wide, greenish to white, maturing with a dull purple apex and striations down to the base; fruiting umbellules c. 5 cm long, 4 cm wide, mulberry shaped, with up to 80 fruits densely pressed together.

Notes.

Osmoxylon truncatum is common in both the limestone and volcanic islands of Palau and is often found in villages near dwellings. The flowers are used for decorations in traditional and modern customs and events. The species is distinguished from the other Palau Osmoxylon taxa by its leaves with 11-15 lobes, ciliate crested stipules, and its much larger inflorescences with up to 80 flowers and fruits.

Specimens examined.

Palau. Aimeliik State: along road to power plant, Dec 2014, Costion 3987-3989, (BNM, US); Airai State: just south of main entrance to airport, 07°21'49.0"N; 134°31'54.1"E, 64 m,12 Nov 2013 (fl., fr.), G.M. Plunkett 2716 (BNM, NY); Ngetkib, agroforest, 7 Aug 2007 (fr.), M. Balick 4475 (BNM, NY); near airport, 15 Oct 1978 (fl.) Shearard & Spence 89 (BISH); Babeldaob, 1 Nov 1933 (fl.) Herre 71 (BISH); Kaiguru, 15 Apr 1936 (fl.), Takamatsu 1611 (BISH); Koror State: Koror, BNM botanical garden, 9 Mar 2007 (ster.), Kitalong 30907 (BNM); Coral island, Aug 1932, Kanehira 1853 (FU); Aug 1929, Kanehira 129 (FU); BNM botanical garden, 5 Dec 2014, Costion 3980-3986, 3990-4000 (BNM, US); Melekeok State: Aug 1932, Kanehira 2057 (FU); Ngaraard State: tributary of Ngereakl R., 20 Jan 1978 (fr.) J. Canfield 397 (BNM, BISH); Ngarchelong State: west of Pkulrengerelong, 3 Jan 1978 (ster.), J. Canfield 304 (BMM); Ngaremlengui State: upper Ngarmiskan R., 8 Dec 1978 (fr.) J. Canfield 650, 651, (BNM); Ngatpang State: Mechutelngatpang, 5 Aug 2008 (fr.), M. Balick 4594 (BNM, NY); Ngiwal State: along Ngareboku R., 17 Jan 1978 (ster.), J. Canfield 362 (BNM); Aug 1932, Kanehira 2065 (FU), Aug 1932, Kanehira 2066 (FU).

Figures

Figure 3. Osmoxylon truncatum a compound infructescence with mature fruits b mature fruits c compound inflorescence with un-opened flowers d mature leaf e one mature inflorescence f flower head g one fertilized inflorescence, without corollas h petiolar stipule i petiole crests.