Selaginella apoda
Selaginella acanthonota
meadow spike-moss, sélaginelle apode
sandy spike-moss, spiny 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; rhizomatous stems with budlike branches, these sometimes inconspicuous;
aerial stems erect or ascending, lateral branches conspicuously determinate.
delicate, papery.
monomorphic, in pseudowhorls of 4 or 5, tightly appressed, ascending, green, narrowly triangular-lanceolate or narrowly lanceolate, 2–3.25 × 0.4–0.6(–0.7) mm;
abaxial ridges present;
base rounded to cuneate, slightly decurrent to adnate, pubescent;
margins ciliate, cilia transparent, spreading at base, dentiform, ascending toward apex, 0.02–0.1 mm;
apex plane, attenuate or seldom slightly keeled;
bristle white or whitish to transparent, sometimes with brownish to reddish band at base marking breaking point (in old leaves), straight, puberulent, (0.35–)0.5–1.4 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, (0.5–)1–3(–3.5) cm;
sporophylls ovate-lanceolate to lanceolate, abaxial ridges not prominent, base pubescent, margins ciliate, apex bristled.
axillary, throughout stem length or restricted to proximal 1/3 of stem, 0.05–0.1 mm diam.
borne on upperside of stems, restricted to rhizomatous stems or lowermost base of aerial stems (seldom on distal 2/3, if so, short), mostly aerial, 0.25–0.43 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.
Selaginella apoda
Selaginella acanthonota
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 acanthonota is a member of the S. arenicola complex, a taxonomically difficult group. Specimens of S. acanthonota from the northern part of its range (e.g., North Carolina, South Carolina, and Georgia) tend to have rather prostrate underground (rhizomatous) stems, with ascending to erect, short aerial stems. Those from Florida have rather ascending underground (rhizomatous) stems and more slender aerial stems. Selaginella acanthonota, in addition to features given in the description, is characterized by having hairs running lengthwise along or at least to the proximal half of the ridges bordering the abaxial groove of the leaves and sporophylls, and, usually, puberulent leaves and sporophyll apices. The hairs on the ridges sometimes break off easily or are somewhat enclosed within the abaxial groove (when the ridges close as a response to dryness), but they can be seen under a microscope. More systematic studies are needed within S. acanthonota and the entire S. arenicola complex.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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