Brachypterum (Wight & Arnott, 1834) Bentham, 1837

Song, Zhu-Qiu, 2023, Taxonomic notes on the genus Brachypterum (Fabaceae: Millettieae), Phytotaxa 584 (4), pp. 251-263 : 258

Key to species of the genus Brachypterum

1 Trees ...................................................................................................................................................................................................2

- Scandent shrubs..................................................................................................................................................................................4

2 Leaflets 19–43, terminal ones 0.5–0.9 cm wide; corolla purplish; pods glabrescent...................................... B. microphyllum Miq.

- Leaflets 7–25, terminal ones 0.9–2.6 cm wide; corolla white to pale pink; pods sericeous ..............................................................3

3 Bracts subtending inflorescence 5–10 mm long; ovules 2–4; pods with 1–2 seeds; restricted to Philippines..................................... .............................................................................................................................................. B. cumingii (Benth.) Adema & Sirich.

- Bracts subtending inflorescence usually less than 1 mm long, rarely 3 mm long; ovules 7–11; pods usually with 3–6 seeds; not from Philippines.......................................................................................................... B. robustum (Roxb. ex DC.) Dalzell & A. Gibson

4 Leaflets 5–9, terminal ones usually more than 7 cm wide; brachyblast absent; standard petal tomentose outside, with 2 small basal callosities ............................................................................................................... B. koolgibberah (F.M.Bailey) Adema & Sirich.

- Leaflets 7–19, terminal ones usually less than 5 cm wide; brachyblast present; standard petal glabrous or sparsely pubescent outside, with no callosities .................................................................................................................................................................5

5 Inflorescences 3–6 cm long, with 2–3 flowers per brachyblast; corolla pale greenish........................................................................ ............................................................................................................................................. B. thorelii (Gagnep.) Adema & Sirich.

- Inflorescences 10–40 cm long, with 3 or more flowers per brachyblast; corolla white, pink or purple ............................................6

6 Leaflets 13–19; pods usually more than 3 seeds .......................................................... B. eriocarpum (F.C.How) Adema & Sirich.

- Leaflets 7–13; pods usually with 1–2 seeds .......................................................................................................................................7

7 Leaflets densely sericeous below .......................................................................................................................................................8

- Leaflets glabrescent or sparsely pubescent below..............................................................................................................................9

8 Pods tomentose, with a 4–6 mm long stipe ..................................................................... B. involutum (Sprague) Adema & Sirich.

- Pods glabrescent or sparsely pubescent, withan about 2.5 mm long stipe ............... B. pseudinvolutum (Verdc.) Adema & Sirich.

9 Terminal leaflets obtuse at apex, usually retuse; stipels present, or sometimes inconspicuous; pods 0.8–1.2 cm wide (mean: 1.0 cm)............................................................................................................................................................. B. scandens (Roxb.) Miq.

- Terminal leaflets acuminate at apex; stipels absent; pods 1–2.2 cm wide .......................................................................................10

10 Leaflets 5–7, terminal ones 8–11 cm long; pods 1–1.5 cm wide, without stipes ........... B. philippinense (Merr.) Adema & Sirich.

- Leaflets 9–11, terminal ones 4.8–6 cm long; pods 1.4–2.2 cm wide, with a 4–9 mm long stipe......................................................... ..................................................................................................................................... B. submontanum (Verdc.) Adema & Sirich.