Selaginella apoda
Selaginella weatherbiana
meadow spike-moss, sélaginelle apode
Weatherby's spike-moss
prostrate to short-creeping, sparsely branched, branches mostly simple or 1-forked, flat, not articulate, glabrous.
radially symmetric, underground (rhizomatous) and aerial, not readily fragmenting, irregularly forked; rhizomatous and aerial stems often with 1 branch arrested, budlike, tips straight;
aerial stems erect, less often ascending, cespitose, stout, branches not conspicuously arrested, budlike branches mostly near base.
delicate, papery.
dimorphic, not clearly ranked.
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, (0.7–)1–3 cm;
sporophylls narrowly ovate-lanceolate to lanceolate, abaxial ridges prominent, base glabrous, margins denticulate to short-ciliate, apex keeled, bristled.
axillary, throughout stem length or restricted to proximal 1/3 of stem, 0.05–0.1 mm diam.
borne on upperside of stems, mostly restricted to rhizomatous stems or to lower 1/2 of aerial stems, 0.16–0.26(–3) 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.
stem leaves persistent, loosely appressed, ascending, often incurved, scalelike.
stem leaves tightly appressed, ascending, green, linear-lanceolate to narrowly lanceolate, 1.7–2.4 × 0.36–0.43 mm;
abaxial ridges prominent;
base cuneate and decurrent on main stem or rounded and abruptly adnate on apical branch portions, glabrous or pubescent;
margins short-ciliate at base, cilia transparent, spreading, denticulate, and ascending toward apex, 0.03–0.06 mm;
apex keeled;
bristle transparent to opaque or yellowish to brownish (on old leaves), puberulent to smooth, 0.3–0.6(–0.7) mm.
= 18.
Selaginella apoda
Selaginella weatherbiana
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.)
One of the most striking features of Selaginella weatherbiana is that at branch forks the larger branch continues to grow as a vegetative shoot, and the smaller one usually forms a strobilus. Therefore, the strobili appear to be lateral rather than terminal. Selaginella weatherbiana grows in close association with S. underwoodii (R. M. Tryon 1955). The two species (as well as S. mutica var. mutica) are very often mixed on herbarium specimens.
Of conservation concern.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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