Holarrhena, Brown, 1809

Ambika, Viswanathan Pillai, Jose, Sojan & Suresh, Veerankutty, 2024, Holarrhena parishadii (Apocynaceae), a new species from Palakkad gap of Western Ghats, South India, Phytotaxa 664 (4), pp. 290-296 : 294

Key to the genus Holarrhena

1. Leaves subcoriaceous when dry, apex mostly rounded or emarginate; follicles erect at least when young; seed body testa pubescent; undershrub or shrub, 2.5 m, mostly much smaller .............................................................................................................. H. curtisii

- Leaves papery when dry, apex mostly acute or acuminate, follicles pendulous, shrub or tree, 0.60–25 m .......................................2

2. Corolla lobes linear, 6–10 times longer than wide; leaf lamina narrowly elliptic, 3–5 times longer than wide, 1–13 × 0.5–3 cm; endemic to Sri Lanka............................................................................................................................................................... H. mitis

- Corolla lobes ovate, 2–5 times longer than wide, Leaf lamina ovate to elliptic, 2–19 × 2–11 cm ....................................................3

3. Inflorescence very dense, fruits 30–60 cm long; shrub or tree to 25 m; West and Central Africa ............................... H. floribunda

- Inflorescence rather lax, fruits 20–37.5 × 0.2–0.9 cm; Shrub or tree 0.6–18 m; eastern and southern Africa and continental Asia ... ............................................................................................................................................................................................................4

4. Shrub or tree to 18 m; corolla lobes 10–24(–30) × 3–8 mm, 3–4 times longer than wide; eastern and southern Africa and continental Asia................................................................................................................................................................................. H. pubescens

- Shrub or small tree to 3 m; corolla lobes 9–10 × 4–5 mm, about twice as long as wide; known only from Palakkad gap of Western Ghats, South India.......................................................................................................................................................... H. parishadii