Spiradiclis, BLUME IN

Tong, Yi-Hua, Xia, Nian-He, Wu, Lei & Vu, Tien Chinh, 2020, Critical notes on Spiradiclis purpureocaerulea H. S. Lo (Rubiaceae) from Vietnam, Adansonia (3) 42 (19), pp. 291-296 : 296

KEY TO THE SPECIES OF SPIRADICLIS BLUME IN VIETNAM

1. Leaf blades cordate; plant creeping ............................................................................. S. hainanensis H. S. Lo

— Leaf blades not cordate; plant ascending or erect ......................................................................................... 2

2. Peduncles longer than 2 cm; corolla tube shorter than 1 cm ........................................................................ 3

— Peduncles shorter than 1 cm; corolla tube longer than 1.6 cm ..................................................................... 4

3. Leaf blades 1-6.5 cm long; secondary veins 3-7 on each side of the midrib; capsules narrowly oblong or linear- oblong .............................................................................................................................. S. caespitosa Blume

— Leaf blades 5-10 cm long; secondary veins 8-15 on each side of the midrib; capsules subglobose ................... ............................................................................................................................................. S. leptobotrya Pit.

4. Plants usually erect, glabrous or subglabrous; leaf blades narrowly elliptic-oblong or elliptic-oblong; calyx lobes 1.7-3 mm long ................................................................................................................ S. coccinea H. S. Lo

4. Plants usually ascending, densely pubescent; leaf blades ovate to ovate-elliptic; calyx lobes 3.5-4.5 mm long ........................................................................................................................... S. purpureocaerulea H. S. Lo