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KEY TO FAMILIES - MOSSES

The diversity of mosses in sub-Saharan Africa is estimated at 78 families, 363 genera and 2791 species (O'Shea 2003), but a more realistic estimate would be nearer 2000 species; totals are updated periodically via checklists and the latest figures can be found on the Tropical Bryology Research website. For those desiring a taxonomic sequence of families, the following list is provided. This reflects the current ideas about the general patterns of evolutionary history with regards to African mosses. It must be noted, however, that this is not necessarily a phylogenetic sequence, and the monophyly of most families (or higher levels) has not been demonstrated. Currently there is a healthy debate with regard to the definition of family limits and relationships within and between families.
Literature. Goffinet, B. & Buck, W.R. 2004. Systematics of the Bryophyta. In: Goffinet, B., Hollowell, V. & Magill, R. (eds.) Molecular Systematics of Bryophytes. St Louis: Missouri Botanical Garden Press. Edwards, S. R. 1984. Homologies and inter-relationships of moss peristome. In: R. M. Schuster (ed.), New Manual of Bryology 2: 658-695.

It is recommended that those trying to identify an unknown moss should use the general key to families below, although those with a good knowledge of the families might find it faster to go straight to the summary of sections.

Taxonomic sequence of families
Key to classes of bryophytes
General key to families (This section is still under construction - comments welcome)
Summary of sections of general key



Class SPHAGNOPSIDA  Order Dicranales (cont.)    Order Hypnales
   Order Sphagnales       Family Eustichiaceae       Family Amblystegiaceae
      Family Sphagnaceae       Family Fissidentaceae       Family Anomodontaceae
        Family Leucobryaceae       Family Brachytheciaceae
Class ANDREAEOPSIDA       Family Rhabdoweisiaceae       Family Calliergonaceae
   Order Andreaeales       Family Rhachitheciaceae
       Family Catagoniaceae
      Family Andreaeaceae    Order Pottiales
       Family Cryphaeaceae
        Family Cinclidotaceae       Family Entodontaceae
Class POLYTRICHOPSIDA       Family Pottiaceae       Family Fabroniaceae
   Order Polytrichales       Family Serpotortellaceae       Family Fontinalaceae
      Family Polytrichaceae       Family Splachnobryaceae       Family Hylocomiaceae
     Order Splachnales       Family Hypnaceae
Class BRYOPSIDA       Family Splachnaceae       Family Lembophyllaceae
   Order Diphysciales       Family Meesiaceae       Family Leptodontaceae
      Family Diphysciaceae    Order Orthotrichales       Family Leskeaceae
   Order Encalyptales
       Family Orthotrichaceae       Family Leucodontaceae
      Family Encalyptaceae    Order Hedwigiales       Family Meteoriaceae
   Order Funariales       Family Hedwigiaceae       Family Myriniaceae
      Family Funariaceae       Family Rhachocarpaceae       Family Neckeraceae

      Family Gigaspermaceae

    Order Bryales       Family Phyllogoniaceae
   Order Splachnales       Family Aulacomniaceae       Family Plagiotheciaceae
      Family Splachnaceae       Family Bartramiaceae       Family Prionodontaceae
   Order Bryoxiphiales       Family Bryaceae       Family Pterigynandraceae
      Family Bryoxiphiaceae       Family Mniaceae       Family Pterobryaceae
   Order Grimmiales       Family Orthodontiaceae       Family Pylaisiadelphaceae
      Family Grimmiaceae       Family Phyllodrepaniaceae       Family Regmatodontaceae
      Family Ptychomitriaceae    Order Rhizogoniales       Family Rhytidiaceae
      Family Seligeriaceae       Family Rhizogoniaceae       Family Rigodiaceae
   Order Archidiales       Family Racopilaceae       Family Rutenbergiaceae
      Family Archidiaceae    Order Hookeriales       Family Sematophyllaceae
   Order Dicranales       Family Adelotheciaceae       Family Stereophyllaceae
      Family Bruchiaceae       Family Daltoniaceae       Family Symphyodontaceae
      Family Calymperaceae       Family Hookeriaceae       Family Thuidiaceae
      Family Dicranaceae       Family Hypopterygiaceae  
      Family Ditrichaceae       Family Leucomiaceae  
      Family Erpodiaceae       Family Pilotrichaceae  
     
     

Keys to the classes and families of mosses of sub-Saharan Africa

The following keys are intended to assist in the identification of mosses from sub-Saharan Africa. The keys are designed to stress gametophytic features whenever possible. Sporophytes are often not present in collected material, and, in some cases, not known in our area or elsewhere. For this reason, and because a number of families exhibit considerable variation, families are often keyed out in more than one place. The keys often emphasize salient features of families with primary emphasis on gametophytic characters, secondarily on sporophytic characters, and lastly on habitat or geography. In using the keys, one normally follows the lead that best fits the two alternative choices given. When one reaches a point in the keys at which neither lead appears appropriate, one then should follow both, hopefully ending with two alternative families. Both should then be compared carefully with the descriptions, keys to genera and illustrations. If neither alternative appears appropriate, then one must back-track in the keys to find where the problem of interpreting a particular character exists. In any case, one should read carefully the family description, keeping in mind the variation exhibited by that family (this applies equally to genera).


Key to the classes

1. Plants typical of boggy or marshy sites, whitish; branches spirally arranged in fascicles; laminal cells of stem and branch leaves alternating between leucocyst (hyaline cells) and chlorocyst (green) cells; capsules globose, supported by a pseudopodium Sphagnopsida (Sphagnaceae)
1. Plants mostly of drier sites, mostly green, yellow or brown; laminal cells uniformly similar with chlorophyll, or chlorophyll cells layered between hyaline cells above and below; not alternating between hyaline and green cells; capsules variously shaped, supported by a pseudopodium or seta 2
2. Plants small, deep dark red or blackish, largely restricted to open high elevations; capsules supported by a pseudopodium, opening by 4 (division throughout) or 8 (distal tip) slits or valves Andreaeopsida (Andreaeaceae)
2. Plants small to medium sized or robust, present in all environments; capsules stegocarpic, supported by a seta, generally with a peristome and operculum 3
3. Leaves bearing rows of lamellae on distal upper surface; capsules with a single series of peristome teeth, teeth 16, 32, or 64, distally attached to a circular membrane (epiphragm) Polytrichopsida (Polytrichaceae)
3. Leaves lacking rows of lamellae, or very rarely so (see Grimmiaceae, Pottiaceae); capsules either with a peristome in a single series with 16 teeth, or a double series with the outer series of 16 teeth (exostome), and an inner series with a basal membrane bearing 16 segments and cilia (endostome); in a number of cases the peristome is reduced Bryopsida


General key to the families


1. Plants whitish, laminal cells alternating or layered between leucocyst and chlorocyst cells
1. Plants variously green, yellow to golden or brown to blackish; laminal cells uniform, neither layered or alternating between leucocyst and chlorocyst cells walls
2
2. Upper distal surface of leaf with discontinuous or continuous rows of lamellae
2. Upper distal surface lacking lamellae
3
3. Plants acrocarpous; stems erect or occasionally spreading, solitary or in short to long tufts or cushions; sporophytes terminal on stems or branched innovations; peristome single (a single series of teeth 16 or divided into 32 narrow segments) or double (two series, outer series of 16 teeth, inner series often with 16 segments and often cilia atop a short to tall membrane)
4
3. Plants pleurocarpous, stems creeping, spreading, or pendent, frondose or dendroid from a conspicuous or inconspicuous creeping primary stems; sporophytes lateral on stems; peristome double or variously reduced
6
4. Leaves arranged in 2 ranks (distichous) or 4 ranks (but appearing 2-ranked)
4. Leaves arranged in 3 or more rows
5
5. Laminal cells papillose or mammillose
5. Laminal cells smooth
6. Leaf costa absent, short and forked, or elongate and double
7
6. Leaf costa single
9
7. Leaves distinctly 2-ranked, usually strongly folded
7. Leaves in 3 or more ranks, when complanate often with lateral asymmetric leaves (occasionally partially folded on one side) and median symmetric leaves
8
8. Leaves ecostate (some to most leaves lacking a costa, but some leaves may have a weak to strong costa)
8. Leaves with costa, short and forked or elongate and double
9. Leaves strongly dimorphic, upper or lower leaves on stems smaller and differing in shape than larger lateral leaves
9. Leaves monomorphic, usually differing if at all between smaller branch leaves or lateral leaves asymmetric and median leaves symmetric
10
10. Laminal cells mammillose or papillose
10. Laminal cells smooth

 

Summary of Sections


Section 1. Plants whitish, laminal cells alternating or layered between leucocyst and chlorocyst cells.

Plants whitish, occasionally reddish or purplish tinged; laminal cells differentiated, alternating or layered between hyaline cells (leucocysts) and green cells (chlorocysts).


Section 2. Upper distal surface of leaves with rows of lamellae or short filaments.

PLANTS ACROCARPOUS

Plants acrocarpous, stems mostly erect or occasionally spreading, solitary or in short to tall loose or dense tufts; sporophytes terminal on stems or branched innovations; peristome single or double, rarely absent.


Section 3. Plants acrocarpous. Leaves arranged in 2 ranks (distichous) or in 4 ranks but appearing 2-ranked.

Section 4. Plants acrocarpous. Leaves in 3 or more rows. Laminal cells papillose or mammillose (cells often isodiametric or shortly elongate).

Section 5. Plants acrocarpous. Leaves in 3 or more rows, ranked or not. Laminal cells smooth.


PLANTS PLEUROCARPOUS

Plants pleurocarpous; stems creeping, spreading, forming mats, or pendent, frondose or dendroid, often forming tufts, from a creeping primary stem; sporophytes lateral on stems; peristome double or variously reduced, rarely absent.

Section 6. Plants pleurocarpous. Leaves 2-ranked, strongly folded throughout.

Section 7. Plants pleurocarpous. Leaves ecostate.

Section 8. Plants pleurocarpous. Leaves costate; costae short and forked or double and elongate (often 1/2 or more than lamina length).

Section 9. Plants pleurocarpous. Leaves costate; costa single. Leaves strongly dimorphic, upper or lower leaves on stem smaller and differing in shape from larger lateral leaves.

[Sections 10-11. Plants pleurocarpous. Leaves monomorphic, usually differing only in that branch leaves are somewhat smaller, differing in shape or not, or that lateral leaves asymmetric and median leaves symmetric, or primary and secondary stem leaves differentiated; costa single.]

Section 10. Plants pleurocarpous. Leaves costate; costa single; laminal cells mammillose or papillose.

Section 11. Plants pleurocarpous. Leaves costate; costa single; laminal cells smooth.