Selaginella apoda
Selaginella mutica
meadow spike-moss, sélaginelle apode
bluntleaf spikemoss
prostrate to short-creeping, sparsely branched, branches mostly simple or 1-forked, flat, not articulate, glabrous.
radially symmetric, long- to short-creeping, not readily fragmenting, ± regularly forked, without budlike arrested branches, tips straight;
main stem indeterminate, lateral branches determinate, 1–2-forked.
delicate, papery.
monomorphic, in ± alternate pseudowhorls of 3, tightly appressed, ascending, green, lanceolate to linear-lanceolate or lanceolate-elliptic, 1–2 × 0.45–0.6 mm;
abaxial ridges well defined;
base rounded and adnate, sometimes slightly decurrent, pubescent or glabrous;
margins ciliate to denticulate, cilia transparent, spreading or ascending, 0.03–0.17 mm;
apex keeled, obtuse or slightly attenuate, nearly truncate in profile, blunt to short-bristled;
bristle transparent to greenish transparent or whitish, smooth, 0.06–0.45 mm.
paired or solitary, lax, flattened, 1–2 cm;
sporophylls ovate to ovate-deltate, strongly keeled, keel dentate, base slightly cordate to rounded, margins with scattered teeth, apex acuminate;
megasporophylls larger and wider than microsporophylls, usually on underside of strobili.
solitary, (0.6–)1–3 cm;
sporophylls ovate-lanceolate, ovate-elliptic, or deltate-ovate, abaxial ridges well defined, base glabrous, margins ciliate to denticulate, apex strongly to slightly keeled, short-bristled to blunt.
axillary, throughout stem length or restricted to proximal 1/3 of stem, 0.05–0.1 mm diam.
borne on upperside of stems, throughout stem length, 0.13–0.23 mm diam.
leaves distant, green, ovate to ovate-lanceolate, 1.35–2.25 × 0.75–1.35 mm;
base slightly cordate;
margins green or with 1 row of transparent cells, serrate;
apex acute, ending in teeth.
leaves ovate-lanceolate, 1–1.6 × 0.45–0.7 mm;
base oblique on inner side, rounded and prominent on outer side;
margins green or with row of transparent cells, serrate;
apex straight, acuminate to long-acuminate.
= 18.
Selaginella apoda
Selaginella mutica
Selaginella apoda is the central component of a taxonomically difficult species complex of eastern North America. It is closely related to S. eclipes (see discussion) and S. ludoviciana. Naturally occurring and experimental hybrids between S. apoda and S. ludoviciana have been reported (P. Somers and W. R. Buck 1975; T. R. Webster 1990). Also, some evidence indicates that hybrids may occur between S. apoda and S. eclipes. More studies are needed in this complex.
The species in the S. apoda complex may be best classified under subg. Homostachys of J. G. Baker (1883, 1887), with which they share flattened strobili and larger sporophylls (megasporophylls) that are usually in the same plane as the vegetative lateral leaves. They are, however, treated here with the other heterophyllous species of subg. Stachygynandrum until a reassessment of the classification of the genus Selaginella can be made.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
Selaginella mutica, S. underwoodii (R. M. Tryon 1955; C. A. Weatherby 1943), and S. wallacei all have similar patterns of variation. Study is needed to assess to what degree such variability is caused by environmental or genetic factors. Within S. mutica, two rather distinct, morphologic extremes are recognized here as varieties. Many specimens having leaves with spreading, long, marginal cilia and a short, broken, apical bristle have been considered intermediate between the two varieties, but they belong in S. mutica var. mutica.
Selaginella mutica may be one of the parent species of the putative hybrid species S. × neomexicana (see discussion). Selaginella mutica is often found growing in the same habitat with S. underwoodii, S. × neomexicana, and S. weatherbiana. According to R. M. Tryon (1955), where the two grow together, S. mutica mats gradually entirely replace mats of S. underwoodii over time. Selaginella mutica is sometimes confused with S. viridissima.
Varieties 2.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
1. Margins of sporophylls usually long-ciliate, seldom denticulate, cilia spreading; apex of leaves with or without bristle, 0.03–0.06 mm; leaf margins long- ciliate, rarely denticulate, cilia spreading. | var. mutica |
1. Margins of sporophylls mostly very short-ciliate to denticulate, cilia and teeth ascending; apex of leaves with bristle 0.2–0.45 mm; leaf margins short-ciliate to denticulate, cilia and teeth ascending. | var. limitanea |
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