Key to the species of Nervilia occurring in Africa
Notes:
All characters used refer to unpollinated flowers in full anthesis (A) and to fully developed and mature leaves (B). Variable species are keyed out in more than one place. The variability of some of the species makes it necessary, in extreme cases, to know both flowering scape and leaf for a certain determination. However, most "single-aspect" specimens (leaf only or flowers only) are easily determinable.
Unfortunately, "geographical characters" have had to be used to separate the leaves of Nervilia pectinata and Nervilia subintegra. Apart from a difference in mean size they are indistinguishable.
Key to vegetative specimens of the genus Nervilia:
1 | Leaf pubescent | 2 |
Leaf glabrous | 7 | |
2 | Leaf distinctly polygonal or star-shaped in outline, thin, held a few cm above ground | 3 |
Leaf reniform to orbicular, often rather thick, mostly prostrate | 4 | |
3 | From Malawi, Mozambique, Zambia, Zimbabwe or southern Tanzania | Nervilia pectinata |
From Northern Hemisphere or lower Zaire | Nervilia subintegra | |
4 | A ± wide zone near main veins glabrous, leaf width 4-6 cm, Madagascar only | Nervilia affinis |
Hairs also on or near main veins | 5 | |
5 | Leaf small, < 3 cm across, purple below, reticulated with silver above (silvery pattern may be absent) | Nervilia stolziana |
Leaf larger, 4.5-20 cm wide, green on both sides | 6 | |
6 | Leaf 4.5-14 cm wide | Nervilia crociformis |
Leaf larger, 18-22 cm across, Madagascar only | Nervilia leguminosarum | |
7 | Leaf base attenuate to truncate, leaf blade erect | 8 |
Leaf base cordate, leaf blade prostrate or raised | 10 | |
8 | Leaf olive green with silvery veins above, purple below | Nervilia ballii |
Leaf green on both sides | 9 | |
9 | Leaf blade > 4 cm wide | Nervilia shirensis |
Leaf blade < 4 cm wide | Nervilia kotschyi vat. purpurata | |
10 | Petiole very long, >10 cm; leaf held well above ground | Nervilia bicarinata |
Petiole < 6 cm; leaf often more or less prostrate | 11 | |
11 | Leaf pleated with ragged keels running along the ridges of the pleats | Nervilia kotschyi var. kotschyi |
Leaf without such keels | 12 | |
12 | Leaf large, > 9 cm wide, very pleated | Nervilia renschiana |
Leaf smaller, < 9 cm wide, not pleated | 13 | |
13 | Leaf very small, not more than 2 cm wide | 14 |
Leaf larger | 15 | |
14 | Leaf with silvery rays (silvery pattern may be absent), ± orbicular, purple below | Nervilia petraea |
Leaf without silvery pattern, broadly cordate, green below, Madagascar only | Nervilia lilacea | |
15 | Leaf above marbled or tesselate with silver or light green | 16 |
Leaf above uniformly green | 17 | |
16 | Leaf very conspicuously tesselated silver and dark green, reniform, shortly apiculate or with rounded apex | Nervilia adolphi var. seposita |
Leaf marbled in light and dark green, cordate, with prominent, triangular apical part | Nervilia fuerstenbergiana | |
17 | Leaf <5 cm wide | 18 |
Leaf > 5 cm wide | 19 | |
18 | Leaf with triangular apex, not strongly prostrate, never dark purple below | Nervilia lilacea |
Leaf with more or less rounded apex, often strongly prostrate and dark purple below | Nervilia adolphi var. adolphi | |
19 | Leaf spade-shaped, slightly longer than wide, thick | Nervilia kotschyi var. kotschyi |
Leaf reniform, cordate to orbicular, wider than long, ± thin | 20 | |
20 | Leaf broadly heart-shaped with distinct apical point, not strongly prostrate | Nervilia adolphi var. adolphi |
Leaf reniform to almost orbicular without distinct apical point, often strongly prostrate | Nervilia crociformis |
And species without a key:
Nervilia similis | SW. Tanzania. |
Nervilia hirsuta | Madagascar. |
World Checklist of Monocotyledons. The Board of Trustees of the Royal Botanic Gardens, Kew. Published on the Internet; http://www.kew.org/wcsp/monocots/ accessed 06/11/2013