Generic key to the Hypnaceae of Tropical Africa

 

E. Petit

Extracted from: Bull. Jard. Bot. Nat. Belg. 48: 135-181 (1978)

Translated by C.R. Stevenson

 

1 Adjacent leaves very different from each other, the latero-dorsal being asymmetric, the ventral ± symmetric and clearly smaller Rhacopilopsis
1* Neighbouring leaves all more-or-less similar, though sometimes the lateral leaves are ± symmetric though ± the same size as the ventral leaves 2
2 Branch leaves differing from the stem leaves in size and sometimes shape. Adjacent leaves ± equal amongst themselves. Cells often papillose at the tip 3
2* Branch and stem leaves ± equal in size though sometimes neighbouring leaves may vary between themselves. Leaf cells rarely papillose 7
3 Branch leaves differing little from stem leaves, ± longly acuminate, and ± strongly toothed 4
3* Branch leaves differing in shape from stem leaves, shortly acuminate or even acute, at least amongst the branch leaves 5
4 Stems pinnate Ctenidium
4* Stems irregularly branched Allorgea
5 Leaf cells linear, without papillae Heterophyllium
(syn. Acanthocladiella)
5* Leaf cells elongate, ending in a papilla 6
6 Capsules erect; exostome teeth non-striate, endostome with linear teeth Leptohymenium
6* Capsules pendant or horizontal; exostome with teeth horizontally striate; endostome teeth narrowly triangular (African species of Gollania included Mittenothamnium
7 Adjacent leaves differing, the lateral ones ± asymmetric (falcate/secund leaves are here regarded as being symmetric) 8
7* Adjacent leaves all similar, lateral leaves being symmetrical or falcate-secund 12
8 Leaf cells ± elongate-hexagonal, 15 µ wide or more; cell walls at the leaf margins clearly thinner than those in the interior Vesicularia
8* Leaf cells linear and very narrow. Marginal leaf cell walls not thinner than those in the interior (genera difficult to separate: probably poorly defined) 9
9 Leafy branches flattened; leaves partly plicate 10
9* Leafy branches not flattened, or only slightly so; leaves not plicate 11
10 Leaf cells non-papillose, though occasionally with terminal papilla Isopterygium
10* Walls of leaf cells finely papillose Taxiphyllum
11 Capsules tilted Ectropothecium
11* Capsules erect Herzogiella
12 Leaves falcato-secund or spreading; branches often lying dorso-ventrally or flattened. Capsules inclined or pendent 13
12* Leaves imbricated, at least when dry; branches often erect and ± cylindric. Capsules erect and ± upright 17
13 Leaves longly nerved; strongly plicate, papillose Rhytidium
13* Leaves nerveless, or with a short double nerve; not, or only slightly, plicate 14
14 Capsules covered in large mammillae Trachythecium
14* Capsules smooth or nearly so 15
15 Capsules ovoid or cylindrical, generally upright; leaf cells sometimes bearing a terminal papilla Ectropothecium
15* Capsules ovoid-elongate or cylindrical, generally curved; leaf cells epapillose 16
16 Leafy stems flattened Breidleria
16* Leaft stems not flattened, often dorso-ventral Hypnum
17 Endostome made up of narrowly triangular teeth, keeled or broken up longitudinally and sometimes with rudimentary cilia Pylaisia
17* Endostome of linear teeth without cilia 18
18 Endostome teeth knotty/gnarled, non-perforate Bryosedgwickia
18* Endostome teeth with linked perforations Platygyrium

TBG53/hypn Issue 1 - 19.12.1997

---green line---