Selaginella mutica
Selaginella willdenowii
bluntleaf spikemoss
vine spike-moss, Willdenow's spikemoss
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.
high-climbing, many times branched, branches 4–5-forked, flat, not articulate, glabrous.
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.
delicate, papery.
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.
solitary, 0.5–2 cm;
sporophylls monomorphic, cordate to ovate-deltate, base glabrous, margins green, entire, apex slightly cuspidate.
borne on upperside of stems, throughout stem length, 0.13–0.23 mm diam.
borne on upperside or underside of stems throughout stem length, 2–3 mm diam.
leaves distant, iridescent, blue-green, ovate to oblong, (2.5–)3–4 X (1–)1.5–2 mm (leaves on tertiary stems ± 1/3 smaller);
basiscopic base rounded, acroscopic base with whitish, long, downward-curving auricle;
margins transparent (whitish and shiny when dry), entire;
apex rounded or obtuse.
leaves falcate-lanceolate or oblique-ovate, 2.4–2.7 × 0.9–1.3 mm;
base auriculate, outer auricle larger than inner;
margins transparent, entire;
apex obtuse.
= 18.
= 20.
Selaginella mutica
Selaginella willdenowii
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.)
Selaginella willdenowii is cultivated principally as a garden plant; it escapes and becomes naturalized in southern Florida. It is now widely distributed and naturalized in many regions in tropical and subtropical America. Its bushy to vinelike habit and blue-green, iridescent leaves are unusual. The iridescence is apparently caused by the effect of thin film interference filters in the leaf epidermis (D. W. Lee 1977). Lee pointed out that the convex epidermal cells in this species may focus light into a single, distal, large chloroplast, possibly adaptations for the improvement of photosynthetic efficiency at the forest floor level.
Selaginella willdenowii is related to S. uncinata (Desvaux ex Poiret) Spring and to S. plana (Desvaux ex Poiret) Hieronymus, which has been reported in Florida (O. Lakela and R. W. Long 1976) but apparently has not become naturalized. Selaginella plana is an erect plant; the secondary branches have obovate-oblong axillary leaves with the apices acute to slightly acuminate, lateral leaves with rounded apices, and median leaves obtuse to rounded. The sporophylls are ovate-lanceolate, with serrate to short-ciliate and very distinctive, white transparent margins.
(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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