1. Diodia teres Walter, Fl. Carol. 87. 1788.
山东丰花草 shan dong feng hua cao
Borreria shandongensis F. Z. Li & X. D. Chen; Diodella teres (Walter) Small; Spermacoce shandongensis (F. Z. Li & X. D. Chen) Govaerts.
Herbs, annual, erect, to 30[-50] cm tall; stems somewhat flattened to slightly [or sharply] 4-angled, pilosulous [and/or pilose to glabrescent]. Leaves sessile; blade drying papery, linear-lanceolate, [8-]20-40 × [1-]3-5[-7] mm, both surfaces hispidulous, base obtuse [to rounded or subcordate], margin weakly [to strongly] revolute, apex acute to acuminate; secondary veins indistinct; stipule sheaths truncate, 1-2.5 mm, pilosulous to glabrescent, with 5-9 setae 1-7 mm. Flowers 1[-3] per axil or 1[-6] per node; bracts reduced. Calyx pilosulous to glabrescent; ovary portion obovoid, 0.5-0.8 mm; limb deeply lobed; lobes lanceolate, ca. 1 mm, pilosulous to glabrescent. Corolla pink [to pale purple or blue], funnelform, hispidulous to glabrescent outside; tube [1.5-]4[-7] mm, glabrescent inside; lobes elliptic-oblong, 0.5-2 mm. Fruit obovoid, [1.5-]3-3.5 mm, papery to bony, hispid to hispidulous, separating into 2 mericarps each with a Y-shaped sulcus on adaxial surface; seeds ca. 2.5 mm, yellowish brown when dry, longitudinally 1-grooved. Fl. and fr. Aug-Sep.
Disturbed, often degraded open ground. S Fujian (Jinmen), Shandong (Qingdao) [native to Antilles and North and South America; adventive in N Africa, Japan, Korea, and Madagascar].
Diodia teres has not been widely reported previously from Asia, but it is known from Japan (Honshu, 18 Oct 1995, S. Tsuagaru & G. Murata 22898, MO!) at a similar latitude to its occurrence in China and probably should be expected elsewhere.