Key to the area around Southern Africa

1a Scape without flowerless bracts 2
1b Scape with flowerless bracts 25
2a Petals undivided 3
2b Petals divided into 3-5 lobes 24
3a Flowers non-resupinate; lip 3-Iobed Holothrix majubensis
3b Flowers resupinate; lip various 4
4a Petals green, yellow or cream, carnose at the apices 5
4b Petals white, sometimes with purplish margins, membranous at apices 18
5a Petals linear; lip lobes short and triangular with obtuse apices Holothrix pilosa
5b Petals broader; lip lobes various 6
6a Lip entire or 3-1obed 7
6b Lip lobes 5-7 13
7a Spur longer than lip Holothrix longicornu
7b Spur shorter than lip 8
8a Lip entire Holothrix exilis
8b Lip 3 lobed 9
9a Lip midlobe broader than long Holothrix brevipetala 
9b Lip midlobe longer than broad 10
10a Hairs on scape stiff, strongly deflexed 11
10b Hairs on scape villose, not strongly deflexed 12
11a Spur c.0.5-2.5 mm long; lip side lobes up to half the length of the midlobe; Drakensberg Holothrix thodei
11b Spur normally 1.5-4 mm long; lip lobes subequal in length; Western Cape and Eastern Cape as far as Grahamstown Holothrix cernua
12a Spur up to 1.8 mm long Holothrix exilis
12b Spur 2-5.5 mm long Holothrix villosa
13a Spur 1.5-4.5 mm long; from Northern, Western and Eastern Cape; if spur only I mm long then scape with strongly reflexed hairs 14
13b Spur 1 - l .5 mm long; from the Drakensberg and Gauteng 17
14a Spur longer than lip Holothrix longicornu
14b Spur shorter than lip 15
15a Base ofpetals adnate to lip; leaves glabrous Holothrix secunda
15b Petals free from lip; leaves with hairs or squamules 16
16a Lip lobes usually less than 2x as long as broad Holothrix brevipetala
16b Lip lobes linear, more than 2 x as long as broad Holothrix cernua
17a Petals more than 5 mm long; flowering from December to April; Drakensberg Holothrix incurva
17b Petals less than 5 mm long; flowering September to October; Gauteng Holothrix micrantha
18a Lip lobes 5 19
18b Lip lobes 7 or more, or lip serrate along margin 20
19a Spur circinnate; leaves uniform in colour; bascs of petals adnate to lip Holothrix parviflora
19b Spur straight; leaves veined with white; petals free from lip Holothrix orthoceras
20a Lip lobes 7 21
20b Lip lobes more than 7, or lip serrated 23
21a Lip lobes broadly triangular except for the outermost lobe on either side, acute; petals tapering to an acuminate apex; occurring east of Port Elizabeth Holothrix orthoceras
21b Lip lobes truncate or obtuse, lobes on either side of the central lobe shorter than midlobe; petal apices obtuse; occurring west of Port Elizabeth 22
22a Inflorescence condensed at apex of spike; spur straight Holothrix mundii
22b Inflorescence lax; spur curved abruptly forward Holothrix aspera
23a Outermost lip lobe on either side longer than central lobes; leaves veined with white; Eastern Cape to Northern Province Holothrix orthoceras
23b Lobes of lip subequal, short and indefinite in number, giving lip a serrated appearance; leaves not veined with white; Eastern Cape Holothrix macowaniana
24a Spur 1.5-2 times the length of the lip; Northern Cape and Southern Namibia Holothrix filicornis
24b Spur as long as or shorter than the lip; 1.5x longer to equal the length of the lip; Eastern Cape, KwaZulu-Natal, Lesotho, Free State and Mpumalanga Holothrix scopularia
25a Petals undivided Holothrix culveri
25b Petals divided 26
26a Flowers dimorphic, upper flowers with much elongated petals and lip lobes Holothrix burchellii
26b Flowers not dimorphic 27
27a Lip lobes hair-like; from Gauteng Holothrix randii
27b Lip lobes filiform, carnose; Northern, Western and Eastern Cape 28
28a Spur half to nearly equal the length of the lip; scape with a covering of short, fine, somewhat velvety hairs Holothrix schlechteriana
28b Spur 1/5 to 1/4 the length of the lip; scape usually glabrous or sometimes with a few short hairs towards base Holothrix grandiflora

World Checklist of Selected Plant Families. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; accessed 05.03.2020