1	Female gametophyte tissue slightly ruminate	T.grandis
–	Female gametophyte tissue deeply ruminate	2
2	Inner wall of seed coat smooth; female gametophyte tissue without grooves	3
–	Inner wall of seed coat with 2 opposite longitudinal ridges; female gametophyte tissue with 2 conspicuous longitudinal grooves	6
3	Leaves 1.2‒3 cm long, usually straight	T.fargesii
–	Leaves 2.5‒7 cm long, slightly to strongly falcate	4
4	Leaves 2.5‒5 cm long, stomatal bands brown; arils green-brown or brown, not powdery	5
–	Leaves 3.5‒7 cm long, stomatal bands silvery gray; arils white powdery	T.jackii
5	Leaf apex acute; seeds obovoid or narrowly obovoid, base acuminate; testa usually smooth	T.jiulongshanensis
–	Leaf apex acuminate; seeds broadly ovoid-globose or globose, base obtuse; testa with irregular and shallow grooves	T.dapanshanica
6	Leaves 2‒3.6 cm long; testa smooth	T.yunnanensis
–	Leaves 1.2‒2 cm long; testa with irregular and shallow grooves	T.parvifolia