Millettia, sensu Dunn, 1912

Song, Zhu-Qiu, Li, Shi-Jin, Vu, Quang Nam & Khang, Nguyen Sinh, 2022, Taxonomic notes on the genus Millettia (Fabaceae: Millettieae) in Vietnam, Phytotaxa 571 (2), pp. 169-185 : 170

Key to species of Millettia from Vietnam

1. Woody climber (sometimes as tree with straggling branches in Millettia extensa ); brachyblasts distinct ........................................2

- Shrub or tree; brachyblasts distinct or indistinct ................................................................................................................................6

2. Stipels present.....................................................................................................................................................................................3

- Stipels absent ......................................................................................................................................................................................5

3. Stamens monadelphous; pods compressed...................................................................................... Millettia extensa (Benth.) Baker

- Stamens diadelphous; pods inflated ...................................................................................................................................................4

4. Flowers 14–17 mm long............................................................................................................................ Millettia pachyloba Drake

- Flowers 7–10 mm long.................................................................................................................... Millettia penduliformis Gagnep.

5. Leaflets densely sericeous below; pods inflated ............................................................................... Millettia sericea (Vent.) Hassk.

- Leaflets sparsely pubescent below; pods compressed.......................................... Millettia densiflora Mattapha, Lanors. & Lamxay

6. Stipels present............................................................................................................................................. Millettia kangensis Craib

- Stipels absent ......................................................................................................................................................................................7

7. Brachyblasts indistinct, bearing only 2 flowers at each node ............................................................................................................8

- Brachyblasts distinct, bearing 3 or more flowers at each node ........................................................................................................11

8. Ovules 2 (rarely 1 or 3); pods rather thick; seeds usually 1 .............................................................. Millettia pinnata (L.) Panigrahi

- Ovules 3–10 (rarely 2); pods compressed; seeds usually 3 or more ..................................................................................................9

9. Pod with two wings ..................................................................................................................................... Millettia diptera Gagnep.

- Pod with no wings ............................................................................................................................................................................10

10. Flowers 10–14 mm long, white to pale green; bracts 2–6 mm long; pods 1.5–3 cm wide.......................... Millettia xylocarpa Miq.

- Flowers 8–10 mm long, purple; bracts 1–1.5 mm long; pods 1.3–2 cm wide ................................... Millettia erythrocalyx Gagnep.

11. Stipules persistent, forming a brush at the top of the branches; standard with basal callosities ......................................................12

- Stipules caducous, not forming a brush at the top of the branches; standard without basal callosities ...........................................13

12. Shrub; flowers ca 1 cm long; pods glabrescent ..................................................................................... Millettia penicillata Gagnep.

- Tree; flowers 2–2.5 cm long; pods tomentose................................................................................................. Millettia cubittii Dunn

13. Bracteoles inserted at middle or upper part of pedicel ............................................................................. Millettia principis Gagnep.

- Bracteoles inserted at apex of pedicel ..............................................................................................................................................14

14. Leaflet blades abaxially appressed pilose..................................................................... Millettia pulchra (Benth.) Kurz var. pulchra

- Leaflet blades abaxially gray tomentose ........................................................ Millettia pulchra (Benth.) Kurz var. tomentosa Prain