Trigonostemon whiteanus (Croizat) Airy Shaw

Yu, R. - Y. & Welzen, P. C. van, 2018, A taxonomic revision of Trigonostemon (Euphorbiaceae) in Malesia, Blumea 62 (3), pp. 179-229 : 225

38. Trigonostemon whiteanus (Croizat) Airy Shaw — Map 15

Trigonostemon whiteanus (Croizat) Airy Shaw (1983a) 68; (1983b) 48. — Cheilosa whiteana Croizat (1942b) 507; Airy Shaw (1963) 365, in note. — Type: FB (Curran) 17733 (holo A; iso K), Philippines, Luzon, Pampanga Prov., Mt Arayat.

Shrubs or trees; flowering branches c. 3 mm diam. Bark 0.3–0.4 mm thick, blackish, smooth, lenticellate, appressed pubescent when young, glabrous when mature; wood yellowish. Stipules not seen (see note 2). Leaves: petiole furrowed above, rounded beneath, 3–5.5 cm long, 1.2–1.5 mm diam (middle part), slightly thickened at base and apex, slightly pubescent above, glabrous beneath; blade broad ovate, 9–13 by 6.5–9 cm, thin coriaceous, base rounded, with 2 adaxial glands, slightly hairy, margin entire, apex acute to acuminate, yellowish green above (when dry), pinkish brown beneath, both sides glabrous; venations triplinerved, midrib slightly raised above and distinctly elevated beneath, nerves 4–7 pairs, curved, slightly raised on lower side, veinlets reticulate. Inflorescences: staminate ones not seen; pistillate ones few branched, pyramidal, densely appressed pubescent, up to 7 cm long and 2.5 mm diam; bracts triangular, 1.5–3 by 1–1.5 mm, apex acuminate, densely appressed pubescent outside, glabrous inside. Staminate flowers not seen. Pistillate flowers 3.5–4.5 mm diam; pedicel 4–6.5 mm long, 0.45–0.8 mm diam, appressed pubescent; sepals triangular to lanceolate, 2–2.5 by 0.8–1.2 mm, apex acuminate, appressed pubescent outside; petals fallen, remnants membranous, yellowish, glabrous; disc lobes c. 0.5 mm wide, appressed pubescent; ovary 2–2.2 mm diam, densely appressed pubescent; style c. 0.5 mm long, trifid, stigma 0.7–0.8 mm long, branches basally connate, apex very slightly thickened and bifid. Fruits and seeds unknown.

Distribution — Philippines (endemic).

Notes — 1. Only known from the type collection. No staminate flowers are available, which makes the generic identification uncertain, but the petals and trifid styles are typical for Trigonostemon , though not exclusively.

2. The development of the stipules seemed to be con- strained, only two very obscure elevations with a few hairs were found instead of normal stipules.