Urtica thunbergiana, Siebold & Zuccarini, 1846

Becker, Karin, Grosse-Veldmann, Bernadette & Weigend, Maximilian, 2017, Weeding the nettles V: Taxonomic and phylogenetic studies of the eastern Asian species Urtica thunbergiana Sieb. & Zucc. (Urticaceae), Phytotaxa 323 (3), pp. 201-216 : 206-207

Key to the subspecies of Urtica thunbergiana

1. Leaf margin regularly dentate.............................................................................................................................................................2

- Leaf margin doubly dentate, usually each large tooth with one small tooth on each side (one or both of the small teeth may be missing on some teeth).......................................................................................................................................................................4

2. Teeth rounded, 2–5 mm long..................................................................................................... Urtica thunbergiana subsp. silvatica

- Teeth pointed, 2–15 mm long.............................................................................................................................................................3

3. Teeth simple, widely triangular; leaf base rounded to cordate; occasionally basal leaves nearly as long as broad with a cordate base and the apical leaves nearly three times longer than broad with a rounded to attenuate base (heteroblastic) ..................................... ..................................................................................................................................................... Urtica thunbergiana subsp. dentata

- Teeth oblong, leaf base rounded, cordate or attenuate; leaves lobulate with lobules with one small tooth, ca. 1 mm long, on each side (the small teeth may be missing); not or weakly heteroblastic.................................. Urtica thunbergiana subsp. thunbergiana

4. Plant sparsely covered with stinging hairs, stinging hairs 1–3 mm long; basal leaves broadly ovate with cordate base .................... ........................................................................................................................................... Urtica thunbergiana subsp. thunbergiana

- Plant densely covered with stinging hairs, stinging hairs up to 4 mm long; all leaves ovate .............................................................. ................................................................................................................................................ Urtica thunbergiana subsp. perserrata