半日花 ban ri hua

Helianthemum ordosicum Y. Z. Zhao et al.

Shrubs dwarf, densely branched, cushionlike, 5-12 cm tall. Old branches brown; branchlets opposite or nearly opposite, tightly appressed white pubescent when young, glabrescent, apex spinose. Leaves opposite; stipules subulate or linear-lanceolate, ca. 0.8 mm, longer than petiole, apex acute; petiole short to almost absent; leaf blade simple, lanceolate or narrowly ovate, 5-7(-10) × 1-3 mm, leathery, both surfaces white puberulous, margin entire, often revolute; midrib slightly impressed. Flowers solitary at tips of branches, 1-1.2 cm in diam.; pedicel 0.6-1 cm, white villous. Sepals 5, unequal, abaxially densely white puberulous; outer 2 sepals linear, ca. 2 mm; inner 3 sepals ovate, 5-7 mm, abaxially 3-ridged. Petals yellow or orange-yellow, obovate, ca. 8 mm, base cuneate. Stamens ca. 1/2 as long as petals; anthers yellow. Ovary ca. 1.5 mm, densely puberulous; style ca. 5 mm. Capsule ovoid, 5-8 mm, puberulous. Seeds brown, ovoid, ca. 3 mm, angled, reticulate-striate, sometimes rugose, apex acuminate.

Rocky hills and slopes in steppe-desert regions; 1000-1400 m. Gansu, Nei Mongol, Xinjiang [C Asia].

Helianthemum songaricum is easily distinguished from other C Asian species by the spine-tipped branches and stipulate leaves. It was listed as rare by Zhou (in Fu & Jin, China Pl. Red Data Book 1: 218-219. 1992).