1	Panicles emerging directly from the main trunk (cauliflorous)	W. nieuwenhuisii
–	Panicles terminal on branches	2
2	Flowers 20–23 mm long; calyx 8–9 mm long; stipules persistent	W. erianthum
–	Flowers 11–15 mm long; calyx 3–4 mm long; stipules caducous	3
3	Flowers 11–13 mm long; stipules 3–4 mm long	W. sumatranum
–	Flowers 13–15 mm long; stipules 1–2 mm	W. scandens