1	"Sterile leaves monomorphic (although those at base of stem may be smaller); plant erect"	2
1	"Sterile leaves dimorphic (at least on the branches); plant erect or creeping"	5
2	"Plant an annual, without a perennial rootstock or fleshy rhizome; stems 2–5 cm tall, simple or divided once or twice near base; sporophylls occupying the greater part of the stem, not forming distinct strobili"	"Selaginella gracillima"
2	"Plant a perennial; stems to 35 cm long, usually much-branched, profusely tufted from a short perennial rootstock or arising singly at short intervals along a stout subterranean widely creeping rhizome; sporophylls forming distinct terminal strobili on all branches"	3
3	"Stems stout, arising singly from a fleshy underground rhizome; branches erect, simple, in 1 plane; roots thick, rarely branched; megaspores 350–500 µm diameter"	"Selaginella uliginosa"
3	"Stems slender, erect; several arising together from a short horizontal rootstock, or prostrate and less tufted; branches often compound and spreading in several planes; roots many, fibrous; megaspores 250–300 µm diameter"	4
4	"Stems erect, to 35 cm tall; sporophylls several, forming distinct strobili"	"Selaginella pygmaea"
4	"Stems prostrate; branches straggling, irregular in length; sporophylls few, in indistinct strobili"	"Selaginella sp. A"
5	"Plants erect or scrambling, unbranched below, with frondose branches (in 1 plane) in the upper parts"	6
5	"Plants to 20 cm tall, creeping or shrubby"	10
6	"Margins of lateral leaves at least partly denticulate or fringed with hairs; branches confined to the upper half of erect stems"	7
6	"Margins of lateral leaves entire; stems branched for most of their length"	8
7	"Stems stramineous; lowermost branches not the longest, giving an oblong-ovate outline to frondose branch system"	"Selaginella longipinna"
7	"Stems reddish; lowermost branches the longest, giving a triangular outline to frondose branch system"	"Selaginella umbrosa"
8	"Stems bearing short stiff pale hairs; base of lateral leaves without acroscopic lobe"	"Selaginella biformis"
8	"Stems glabrous; base of lateral leaves with a distinct acroscopic lobe"	9
9	"Stems often climbing to several metres; branch outline lanceolate; apex of median leaves rounded"	"Selaginella willdenovii"
9	"Stems not climbing, 15–45 cm long; branch outline triangular; apex of median leaves long-acuminate"	"Selaginella plana"
10	"Stems with short hairs"	"Selaginella biformis"
10	"Stems glabrous"	11
11	"Strobili square in cross-section; sporophylls monomorphic"	12
11	"Strobili flattened in cross-section; sporophylls dimorphic"	15
12	"Lateral leaves c. 1.5–2 mm long"	13
12	"Lateral leaves to more than 2 mm long"	14
13	"Stems thread-like, creeping, rooting throughout their length; lateral leaves c. twice as long as wide, entire or denticulate; acroscopic margins at base"	"Selaginella brisbanensis"
13	"Stems wiry, ascending, rooting at base only; lateral leaves c. 3 times as long as wide, with long spinose cilia on base"	"Selaginella andrewsii"
14	"Sterile lateral leaves acute; margins minutely toothed over most of length (sometimes difficult to see)"	"Selaginella kraussiana"
14	"Sterile lateral leaves obtuse; margins ±entire except for a few longish teeth on the acroscopic basal lobe and few minute teeth towards the apex"	"Selaginella australiensis"
15	"Plant shortly creeping, rooting along its length; margins of median leaves denticulate"	"Selaginella ciliaris"
15	"Plants shrubby or erect, often little branched, rooting at the base only; margins of median leaves long-ciliate"	"Selaginella longiciliata"