Orthophytum Beer 1854

Key to the species of Orthophytum with sessile inflorescence

1 Plants with short stem, inconspicuous, 1–4.2 cm long; petals white, obtuse to subacute not cucullate...................... 2

- Plants with long stem, ca 10 cm long; petals green with white margins, obtuse-cucullate........................................ 11

2 Compound inflorescences (rarely simple in O. ulei).................................................................................................... 3

- Simple inflorescences................................................................................................................................................... 4

3 Floral bracts and sepals pink to red............................................................................................................................. 7

- Floral bracts and sepals green..................................................................................................................................... 10

4 Sepals without glandular trichomes; prickles of leaf blade (1.7–) 2–3.5 mm long................................ O. hatschbachii

- Sepals with glandular trichomes; prickles of leaf blade 0.3–1.5 mm long................................................................... 5

5 Leaf blades densely lepidote; sepals narrowly triangular............................................................................... O. humile

- Leaf blades sparsely lepidote; sepals triangular-lanceolate.......................................................................................... 6

6 Leaf blades 8–23 × 0.4–0.7 cm; petals c. 2.5 cm long............................................................................... O. navioides

- Leaf blades 2.5–6.7 × 0.3–0.4 cm; petals c. 1.9 cm long........................................................................ O. mucugense

7 Leaf blades adaxially lepidote, not lucid......................................................................................................................8

- Leaf blades adaxially sparsely lepidote, lucid.............................................................................................................. 9

8 Leaf blades adaxially glabrous at base; petals 1.8–2.5 cm long, apices subacute................................. O. burle-marxii

- Leaf blades adaxially densely lepidote at base; petals 1.3–1.7 cm long, apices obtuse...................................... O. ulei

9 Leaf blades coriaceous, 0.5-1 cm wide; prickles 1.5–3 mm long; floral bracts c. 1.8 × 1 cm; anthers 3.2–3.5 mm long.................................................................................................................................................................... O. amoenum

- Leaf blades subcoriaceous, 0.2–0.4 cm wide; prickles 0.3-0.4 mm long; floral bracts 0.9–1.2 × 0.6–0.7 cm; anthers 2.3–2.5 mm long..................................................................................................................................... O. ophiuroides

10 Leaf blades margins serrate, adaxial surfaces with white-lanate ring at base; prickles 0.5–3.5 cm long; sepals and petals without glandular trichomes.......................................................................................................... O. albopictum

- Leaf blades margins serrulate, adaxial surfaces without white-lanate ring at base; prickles 0.3–0.5 mm long; sepals and petals with glandular trichomes......................................................................................................... O. heleniceae

11 Simple inflorescences..................................................................................................................................... O. vagans

- Compound inflorescences........................................................................................................................................... 12

12 Leaf blades densely lepidote on both surfaces; prickles 0.6-1 mm long....................................................... O. zanonii

- Leaf blades adaxially glabrous toward the; prickles 2-3.5 mm long.................................................. O. pseudovagans