方茎耳草 fang jing er cao

Diplophragma tetrangulare Korthals, Ned. Kruidk. Arch. 2: 149. 1851 ["tetrangularis"]; Hedyotis parryi Hance; H. quadrangularis Miquel; Oldenlandia parryi (Hance) Kuntze; O. quadrangularis (Miquel) Kuntze.

Herbs or subshrubs, erect, perennial or perhaps sometimes annual, to 50 cm tall; stems subterete to 4-angled with angles thickened to ridged, glabrous. Leaves sessile; blade drying papery, linear, linear-lanceolate, narrowly elliptic, or narrowly elliptic-oblong, 1-3.5 × 0.2-0.55 cm, glabrous, base acute to obtuse and usually decurrent, margins usually revolute, apex acute; secondary veins not visible; stipules shortly fused to petiole bases, triangular to truncate, 1-1.5 mm, glabrous, rounded to acute or usually with leaflike appendage, this narrowly elliptic to lanceolate, 2-10 mm, entire or shortly 2- or 3-lobed or ‑setose. Inflorescences terminal and sometimes in axils of uppermost leaves, compound-cymose to paniculate, 4-13 cm, glabrous, many flowered, pedunculate; peduncle 1-5.5 cm; axes mostly regularly dichotomous; bracts linear, 1-2.5 mm; pedicels (or ultimate inflorescence axes) 0.5-3 mm. Flowers subsessile or pedicellate, apparently distylous. Calyx glabrous; hypanthium portion turbinate, 0.8-1 mm; limb lobed nearly to base; lobes narrowly lanceolate to narrowly triangular, 1-1.5 mm. Corolla white, tubular or tubular-funnelform, outside glabrous, inside tomentose at throat and onto lobes; tube ca. 2 mm; lobes lanceolate-oblong, ca. 2 mm. Anthers included or exserted, 0.8-1 mm. Stigmas 0.8-1 mm, included or exserted. Fruit capsular, subglobose, sometimes slightly didymous, ca. 2 × 2 mm, glabrous, septicidally then loculicidally dehiscent; seeds several, black, angled. Fl. and fr. Jul-Nov.

Open fields, grassy slopes, sometimes on ridges of farmlands; low elevations. Guangdong, Guangxi [Borneo, Cambodia, Indonesia, Malaysia, Thailand, Vietnam].

Merrill and Metcalf (Lingnan Sci. J. 16(3): 400. 1937) noted that Valeton provided a much-expanded and detailed description of this species (Bot. Jahrb. Syst. 44: 543. 1910), and they formally synonymized Hedyotis parryi with H. tetrangularis, though as "tetrangularia."