Table 1.

Morphological comparison of diagnostic features of Gastrodia kachinensis and its related species (Meng et al. 2007, Chen et al. 2009, Huang et al. 2015).

Character	G. kachinensis	G. gracilis	G. longitubularis	G. huapingensis
Flower position	bending downwards	nodding	horizontal or slightly bending	pointing slightly downwards
Flower colour	dark yellowish brown	dull brownish	grey-brownish	greyish brown
Perianth tube	punctate, urceolate, outer surface of sepal lobe verrucose, petals orbicular	glabrous, ventricose, outer surface of sepal lobe glabrous, petals ovate	glabrous, slender, outer surface of sepal lobe glabrous, petals ovate or sub-rotundate	glabrous, bell-shaped, outer surface of sepal lobe glabrous, petals ovate
Labellum	orange-yellow towards apex and pale greenish white along each lateral margin, ovate-elliptic, apex truncate, base auriculate-clawed, adaxial surface of lip glabrous, with a pair of twin protuberance-like lamellae only at apex	red or orange-red, ovate-triangluar, apex obtuse, base truncate-clawed, adaxial surface of lip tomentose, with a pair of longitudinal lamellae which are distinctly crested only at apex	red or orange-red, ovate or cordate, apex cuspidate, base rounded-clawed, adaxial surface of lip longitudinally 3-5-grooved, with a pair of longitudinal lamellae near apex	pale yellowish brown, ovate, apex truncate, base obtuse-clawed, adaxial surface of lip with 5 longitudinally ridges, of which central two are much longer and more prominent
Column	As long as lip, with a pair of blade-like lateral wings and acute stelidia at apex	As long as lip, with a pair of semilunar lateral wings and acuminate stelidia at apex	Longer than lip, laterally winged from middle to apex, stelidia acute-triangular at apex	Dimorphic column; extended in some flowers, whereas incurved in some flowers