Table 1. Leaf epidermal characteristics of Holcoglossum, its relatives and outgroup under LM.

Taxa	Shape of cells	Pattern of anticlinal walls	Stomatal apparatus	Size of stoma (L/W)	Stoma index (%)	Stoma grouping (%)	Figures
	(Ad/Ab)
Holcoglossum nujiangense	Pol(4)/Pol(4)	Str/Str	Exist/Exist	1.2/0.9	2.6/2.8	0/28.6	Fig 3, B–C
H. weixiense	Pol(4)/Pol(4)	Str/Str	Exist/Exist	1.4/1.2	2.1/2.8	30.8/22.9	Fig 3, D–E
H. sinicum	Pol(4)/Pol(4)	Str/Str	Exist/Exist	1.1/1.0	2.2/3.1	7.7/11.3	Fig 2, G–H
H. rupestre	Pol(4)/Pol(4)	Str/Str	Exist/Exist	1.1/1.0	2.0/2.6	31.3/23.6	Fig 2, I; Fig 3 A
H. flavescens	Pol(4–6)/Pol(4–6)	Str/Str	Exist/Exist	0.9/1.0	2.0/2.6	7.1/21.4	Fig 2, E–F
H. omeiense	Pol(4–6)/Pol(4–6)	Str/Str	Exist/Exist	-/0.9	-/4.3	-/19.8	Fig 3, H–I
H. lingulatum	Pol(4–6)/Pol(4–6)	Str/Str	Exist/Exist	-/1.1	-/4.0	-/16.5	Fig 3, F–G
H. himalaicum	Pol(6)/Pol(6)	Str/Str	Exist/Exist	1.3/1.1	2.0/2.1	0/0.6	Fig 4, C–D
H. wangii	Pol(6)/Pol(6)	Str/Str	Exist/Exist	0.9/1.0	0.6/0.7	0/0	Fig 1, G–H
H. kimballianum	Pol(6)/Pol(6)	Str/Str	Exist/Exist	1.2/1.3	0.6/0.7	0/0	Fig 1, E–F
H. amesianum	Pol(6)/Pol(6)	Str/Str	Exist/Exist	1.0/1.0	1.9/2.2	0.5/0.5	Fig 1, A–B
H. subulifolium	Pol(6)/Pol(6)	Str/Str	Exist/Exist	1.1/1.1	2.1/1.4	0/0	Fig 1, C–D
Papilionanthe biswasiana	Pol(4–6)/Pol(4–6)	Str-arc/Str-arc	Exist/Exist	1.3/1.3	7.5/7.5	25.0/25.0	Fig 1, I
Ascocentrum ampullaceum	Pol(4–6)/Pol(6)	Str-arc/Str-arc	Exist/Exist	-/1.4	-/2.5	-/3.1	Fig 2, A–B
Vanda pumila	Pol(4–6)/Pol(4)	Str/Str	Absent/Exist	0/1.3	0/2.6	0/0	Fig 2, C–D
Rhynchostylis retusa	Pol(6)/Pol(6)	Str/Str	Exist/Exist	1.3/1.4	3.8/4	0/1.5	Fig 4, A–B
Luisia magniflora	Pol(4–6)/Pol(4–6)	Str-arc/Str-arc	Exist/Exist	1.2/1.2	3.1/3.1	5.8/5.8	Fig 4, E

Pol(4), polygon (quadrilateral); Pol(6), polygon (hexagonal); Pol(4–6), polygon (quadrilateral to hexagonal); Str, straight; Str-arc, straight to arched; Ad/Ab, adaxial epidermis/abaxial epidermis; -, no data analysis.