Euphorbia hyssopifolia L.

Herbs, annual, 15-20 cm tall. Root fibrous, 0.8-1 mm. Stems many from base, ascending or suberect, rarely prostrate, ca. 1 mm thick, usually glabrous, rarely with a few hairs when young. Leaves opposite; stipules interpetiolar, truncate, 0.7-0.9 mm, shallowly lacerate; petiole 1.5-2 mm; leaf blade oblong-elliptic, 0.7-3 cm × 0.3-1.2 mm, thickly papery, base slightly oblique, asymmetric, subrounded, margin sparsely crenate, apex obtuse, adaxially with a few purple spots. Cyathia axillary and terminal, single or in small cymes, peduncle to 4 mm; involucre narrowly campanulate, ca. 0.8 × 0.4-0.5 mm, glabrous, marginal lobes 5, triangular; glands 4, yellow-green, rounded to transversely elliptic, appendages white or pale pink, wider than glands, to 0.7 × 0.5 mm, margin entire to slightly undulate. Male flowers 5-15, exserted; anthers red. Female flower pedicellate, exserted from involucre; ovary smooth, glabrous; styles free; stigma slightly 2-lobed. Capsule 3-angular-ovoid, 2-2.5 × ca. 2.5 mm, smooth, glabrous; fruiting pedicel ca. 2 mm. Seeds ovoid-tetragonal, ca. 1.1 × 0.8 mm, blackish, each side with 3 or 4 transverse furrows; caruncle absent. Fl. and fr. Jan-Apr.

Disturbed areas along railways and roads. Hainan, Taiwan (Gaoxiong, Tainan, Taizhong) [New World; naturalized in the Old World].

Euphorbia hyssopifolia, known by the common name of hyssopleaf sandmat in English and hierba de pollo ("chicken grass") in Spanish, is a member of the spurge family, Euphorbiaceae. It is an annual herb, native to Central and South America and the Southeastern United States. It has also been introduced to west Tropical Africa, India, and Australia.