Trigonostemon stenophyllus Quisumb.

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

37. Trigonostemon stenophyllus Quisumb. — Map 15

Trigonostemon stenophyllus Quisumb.(1930) 330,f. 8. — Type: BS ( Ramos & Edaño) 47331 (holo PNH†; iso A, K, NY*, UC*), Philippines, Luzon, Isabela Prov., Mount Moises .

Shrubs, up to 1 m tall; branches terete, 2–3.5 mm diam, pubescent when young, glabrous when mature. Stipules unknown. Leaves: petioles 1–4 cm long, somewhat pubescent; blade oblong to lanceolate, 5.5–16.5 by 1–2.5 cm, chartaceous, base acute to obtuse, margin entire to slightly distantly serrate, apex acuminate, upper surface brown to dark brown when dry, glabrous, lower surface paler and sparsely pubescent; midrib flat above and elevated beneath, nerves 6 –11 pairs, veinlets reticulate. Inflorescences: staminate ones unknown; pistillate ones axillary, racemose, up to 5.5 cm long, pubescent; bracts narrowly lanceolate, 3–4 mm long. Staminate flowers unknown. Pistillate flowers c. 4.5 mm diam; pedicels slightly thickened towards apex, c. 9.5 mm long, apically c. 0.6 mm diam, appressed pubescent; sepals oblong to lanceolate, c. 3 by 0.7 mm, margin entire, apex acute to acuminate, appressed pubescent outside, glabrous inside; petals oblong-obovate, c. 5 by 2 mm, apex rounded, glabrous; disc lobes elliptic, c. 0.5 by 0.3 mm, apex rounded, glabrous; ovary c. 0.95 mm diam, densely pubescent; styles 0.1–0.2 mm long; stigma linear, c. 1.3 mm long, deeply bifid into 2 arms, each arm c. 1 mm long, slightly thickened near base. Fruits c. 1.2 cm diam, brown, sparsely puberulent, persistent sepals not accrescent; wall c. 0.35 mm thick, exocarp partly detaching. Seeds c. 7 mm diam.

Distribution — Philippines (endemic).

Note — The species is only known from the type. The description is based on Quisumbing (1930). Due to the insufficient specimen seen, especially the lack of staminate flowers, the species is regarded doubtful here. It is probably a synonym of T. filiformis .