Selaginella watsonii Underwood
Family: Selaginellaceae
Watson's spikemoss,  more...
Selaginella watsonii image
Tony Frates  
Plants on rock or terrestrial, forming long or compact cushionlike mats. Stems radially symmetric, decumbent to long-creeping, not readily fragmenting, irregularly forked, without budlike arrested branches, tips straight; main stem conspicuously determinate, lateral branches conspicuously or inconspicuously determinate, strongly ascending, 1--3-forked. Rhizophores borne on upperside of stems, throughout stem length, 0.35--0.55 mm diam. Leaves monomorphic, in alternate pseudowhorls of 4, tightly or loosely appressed, ascending, green, linear-lanceolate, (2.5--)3--4 X 0.5--0.7 mm; abaxial ridges prominent; base cuneate, decurrent, glabrous or sometimes pubescent; margins entire or short-ciliate, cilia transparent, scattered, spreading, 0.05--0.1 mm; apex strongly keeled, obtuse, abruptly bristled; bristle whitish to transparent, smooth, 0.25--0.5 mm. Strobili solitary, 0.5--3(--3.5) cm; sporophylls lanceolate to ovate-lanceolate, abaxial ridges well defined, base glabrous, margins entire, rarely dentate, apex strongly keeled to truncate in profile, short-bristled. On exposed or shaded cliffs, rocky slopes, rock crevices, granite boulders, quartzite rock, gravelly or sandy soil, alpine meadows, or swampy grounds; 1800--4300 m; Ariz., Calif., Idaho, Mont., Nev., Oreg., Utah, Wyo. R. M. Tryon (1955) suggested that Selaginella watsonii is a possible ancestor of (or shares a common ancestor with) S . leucobryoides , S . asprella , and S . utahensis (see discussion).

STEMS: monomorphic, prostrate, not readily fragmenting when dry, the branch tips appearing straight when dry, forming dense usually cushion-like mats. RHIZOPHORES: produced throughout. LEAVES: monomorphic, 2.5-4.0 mm long, narrowly lanceolate, green to yellowish green when hydrated, the base more or less decurrent (similar in color to the stem) and more or less symmetrically narrowed, the tip with a straight or somewhat curved white seta 0.2-0.5 mm long (sometimes breaking off with age), the margins entire, denticulate, or short-ciliate. STROBILI: 5-30 mm long, the sporophylls lanceolate to broadly lanceolate, narrowed to an acute tip with a short seta, the margins entire or denticulate. MEGASPORES: finely rugose to rugose-reticulate, orange. NOTES: Rock outcrops, ledges, boulders, cliffs, and rarely on open gravelly slopes, on igneous and volcanic substrates and sandstone: Coconino, Mohave cos. (Fig. 1H); 2400-2550 m (7850-8400 ft); e WA s to e CA, e to MT and AZ. REFERENCES: Yatskievych, G. and M. D. Windham. Vascular Plants of Arizona: Selaginellaceae. CANOTIA 5 (1): 39-48, 2009.
Yatskievych and Windham 2009
Common Name: Watson's Spikemoss Wetland Status: None Leaves: Monomorphic, 2.5-4 mm long, narrowly lanceolate, green to yellowish green when hydrated, the base more or less decurrent (similar in color to the stem) and more or less symmetrically narrowed, the tip with a straight or somewhat curved white seta 0.2-0.5 mm long (sometimes breaking off with age), the margins entire, denticulate, or short-ciliate. Sporangia: Strobili 5-30 mm long, the sporophylls lanceolate to broadly lanceolate, narrowed to an acute tip with a short seta, the margins entire or denticulate. Megaspores finely rugose to rugose-reticulate, orange. Ecology: Found on rock outcrops, ledges, boulders, cliffs, and rarely on open gravelly slopes, on igneous and volcanic substrates and sandstone from 7,500-8,500 ft (2286-2591 m). Notes: Similar to S. leucobryoides which overlaps in range in the Mojave desert, but is distinguished by S. leucobryoides having dry stems that readily fragment. Ethnobotany: Unknown Etymology: Selaginella is a diminutive of Selago, the name of another similar plant, while watsonii is named for the American botanist Sereno Watson. Synonyms: None Editor: SBuckley 2013
Selaginella watsonii image
Tony Frates  
Selaginella watsonii image
Tony Frates  
Selaginella watsonii image
Tony Frates  
Selaginella watsonii image
Tony Frates  
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
Selaginella watsonii image
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This project made possible by National Science Foundation Award 1410069