Hypericum japonicum Thunb.

Annual herb 0.02-0.05 m tall, erect to decumbent or prostrate and rooting at the base or along stem, unbranched or branched from the base and sometimes also distally and  (when decumbent to prostrate) elsewhere. Stems green, 4- angled, ancipitous above, with lines smooth; internodes 2-52 mm long, usually exceeding leaves. Leaves sessile, spreading, not tetrastichous, persistent; lamina 2-18 x 1-10 mm, broadly ovate-deltoid or ovate to oblong or oblong-lanceolate or elliptic or suborbicular or more rarely oblanceolate or obovate-spathulate, plane, not cucullate, midrib slightly prominent beneath, smooth, paler or sometimes glaucous beneath, membranous; apex obtuse to rounded, margin plane, base cordate-amplexicaul to cuneate or more rarely attenuate, not sheathing, free; basal veins 1-7, sometimes with obscure ascending branches, tertiary reticulation apparently absent; laminar glands dense, punctiform, not prominent. Inflorescence 1-c. 30-flowered, terminal, branching regularly dichasial/monochasial or rarely pseudo-dichotomous at first, sometimes with flowering branches from up to 3 nodes below or sympodial with flowers apparently lateral, the whole diffuse; pedicels (l.4-)2-14 mm long; bracts lanceolate- subulate to foliar. Flowers 4-8 mm in diam., stellate. Sepals 2-5.5 x 0.5-2 mm, subequal to unequal, imbricate, narrowly oblong or rarely lanceolate to elliptic or obovate, acute or obtuse to rounded, margin entire; veins 3-5, unbranched, often with midrib promiment; glands linear, distally punctiform. Petals pale to bright yellow or orange, not veined red outside, 1.7-5 x 0.8-1.8 mm, 0.8-1.3 x sepals, obovate to oblong or elliptic; apiculus obsolete or absent; glands absent. Stamens 5-30, irregular or in 5 obscure groups when few, longest 1.5-2.8 mm, 0.4-0.8 x petals. Ovary l-l.5(-l.8) x 0.5-1 mm, broadly ovoid to subglobose; styles (2)3, 0.4- 0.8(-l) mm long, 0.4-0.6 x ovary; stigmas rather broadly capitate. Capsule (2-)2.5-6 x 1.3-2.8 mm, cylindric to globose, slightly shorter than or more rarely equalling or exceeding sepals. Seeds c. 0.5 mm long; testa finely linear- scalariform.