紫穗槐族 zi sui huai zu
Wei Zhi[1]; Michael G. Gilbert[2]
Tribe description??.
Eight genera and slightly under 250 species: all indigenous to the Americas, and two species found as escapes elsewhere, one of them in China.
The Amorpheae was first thought to be most closely related to the preceding tribe, Psoraleae, but both molecular and morphological analyses now place it as sister to the Dalbergioid clade (eg McMahon & Hufford, Amer. J. Bot. 91: 1219–1230. 2004).
紫穗槐属 zi sui huai shu
Shrubs or shrublets, glandular-punctate. Leaves imparipinnate; stipules small or absent; leaflets many, small. Inflorescences terminal, racemes or spikes, these sometimes in leafy panicles. Calyx 5-toothed. Corolla reduced to just the standard, embracing the stamens and pistil; stamens 10, monadelphous, sheath split adaxially; anthers uniform; ovary sessile, 2-ovuled. Pod oblong, falcate, indehiscent, often densely glandular-warted, falling with persistent calyx. Seed with small hilum.
About 15 species: mostly in North America, including Mexico; one species (introduced) in China.
紫穗槐 zi sui huai
Deciduous shrubs, 1–4 m. stems pubescent, glabrescent. Leaves 10–15 cm; stipules bristlelike; petiole 1–2 cm; leaflets 11–25, ovate to elliptic, 1–4 × 0.6–2 cm, abaxially white puberulent, adaxially glabrous or sparsely pubescent, black glandular-dotted, base broadly cuneate or rotund, apex acute, obtuse or retuse, with a shortly curved spiny tip. Racemes 1-many, terminal or subterminal, 7–15 cm, densely pubescent; bracts 3–4 mm; calyx 2–3 mm, teeth triangular, shorter than the tube; standard purple, obcordate, 6 mm, wings and keel absent; style puberulent. Pod oblong, curved, 6–10 × 2–3 mm, apex beaked, dark brown, strongly glandular-dotted, 1-seeded. Seed reniform, ca. 5 mm, curved upward, lustrous. Fl. May–Jun, fr. Jul–Sep.
Sandy bank of ravine, cultivated or escaped. Anhui, Gansu, Guangxi, Hebei, Heilongjiang, Henan, Hubei, Jiangsu, Jilin, Liaoning, Nei Mongol, Ningxia, Qinghai, Shaanxi, Shandong, Shanxi, Sichuan, Xinjiang [North America, widely introduced in northern Asia and Europe].
This is a variable species with many synonyms and described varieties in North America. It is regarded as a noxious weed in some parts of the United States.