Selaginella mutica
Selaginella arizonica
bluntleaf spikemoss
Arizona spike-moss
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.
not readily fragmenting, prostrate, upperside and underside structurally different, irregularly forked, branches determinate, tips upturned in extremely dry conditions.
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.
conspicuously dimorphic, in 8 ranks, tightly appressed to ascending, green;
abaxial ridges present;
apex with transparent to opaque, flattened bristle 0.1–0.3 mm, sometimes becoming acute (by breaking off of bristle).
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, 5–10 mm;
sporophylls ovate-deltate, abaxial ridges not prominent, base glabrous, margins short-ciliate to denticulate, apex acute.
borne on upperside of stems, throughout stem length, 0.13–0.23 mm diam.
borne on upperside of stem throughout, 0.25–0.3 mm diam.
leaves lanceolate, 2–2.5 × 0.5–0.6 mm;
base decurrent, glabrous;
margins ciliate, cilia transparent to opaque, spreading or ascending, 0.06–0.13 mm.
leaves linear-lanceolate to slightly falcate (on marginal ranks), 1.9–2.25 × 0.4–0.55 mm;
base abruptly adnate, pubescent or glabrous;
margins ciliate, cilia transparent to opaque, spreading, 0.06–0.15 mm.
= 18.
Selaginella mutica
Selaginella arizonica
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 arizonica can be further distinguished from the similar S. peruviana by its broad, thin underside leaves. In S. peruviana the underside leaves are narrow and fleshy.
(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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