7. Bidens parviflora Willdenow, Enum. Pl. 2: 840. 1809.
小花鬼针草 xiao hua gui zhen cao
Annuals. Stems (10-)20-50(-80) cm tall, erect, branched, glabrous or bearing rarely indistinct hairs. Leaves bi- or tripinnatisect with narrow lanceolate or linear-lanceolate to linear segments, with small teeth and incisions on petioles, usually sparsely fine hairy to subglabrous. Capitula discoid, solitary (or 2 or 3) at stem and branch apices, on long peduncles, narrow, subcylindric; calycular bracts linear, shorter than achenes; outer phyllaries green, narrowly linear, herbaceous, finely hairy, shorter than inner ones, inner greenish brown, linear-lanceolate, bearing rarely short bristles only on margin. Florets all tubular, yellow, few. Achenes linear-tetragonal, ± compressed, beset with upright lucid bristles along ribs, otherwise glabrous or finely hairy, unequal in length; inner 15-20(-25) mm, outer shorter, 2 upright awns, 4-5 mm, at top of achenes. Fl. Jul-Sep.
Marshes, fields, streamsides. Anhui, Gansu, Guizhou, Hebei, Heilongjiang, Henan, Jiangsu, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan [Japan, Korea, Mongolia, Russia].