Monographs Details:
Authority:
Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
Family:
Selaginellaceae
Selaginellaceae
Description:
Latin Diagnosis - Foliis lateralibus hispidis, megasporis auran-tiacis et praestertim sporophyllis valde dimorphis insignis. (Gr., distichos, of two rows, referring to the strongly dimorphic sporophylls.)
Species Description - Stems prostrate, creeping, 4-10 cm long, rooting throughout, to 0.4 mm diam., not articulate, not flagelliform, not stoloniferous, pale green; rhizophores filiform, less than 0.1 mm diam.; anisophyllous throughout, leaves membranous, silvery beneath; lateral leaves ovate to obliquely oblong, 2-3 mm long, apex acute, base rounded with eccentric attachment, margin entire to minutely denticulate, hispid on basiscopic half of upper surface; median leaves ovate-lanceolate, keeled-acuminate at apex, base exauriculate, margin minutely denticulate to entire, with white border; axillary leaves ovate-lanceolate, asymmetrical, wider on acroscopic side (similar in size and shape to lateral leaves), exauriculate, margin denticulate only at base, base broadly rounded; strobili 2.3-4.0 mm wide, 6-15 mm long; sp-rophylls dimorphic and of two colors (the upper [median] two ranks green, spreading, the lower [lateral] two ranks nearly colorless and ascending), asymmetric with denticulate margins and with prominent keel; megasporangia in two ventral rows; megaspores light orange to orange, 200270 pm diam., with reticulum of low ridges; microsporangia very small; microspores light orange, with fine reticulum.
Latin Diagnosis - Foliis lateralibus hispidis, megasporis auran-tiacis et praestertim sporophyllis valde dimorphis insignis. (Gr., distichos, of two rows, referring to the strongly dimorphic sporophylls.)
Species Description - Stems prostrate, creeping, 4-10 cm long, rooting throughout, to 0.4 mm diam., not articulate, not flagelliform, not stoloniferous, pale green; rhizophores filiform, less than 0.1 mm diam.; anisophyllous throughout, leaves membranous, silvery beneath; lateral leaves ovate to obliquely oblong, 2-3 mm long, apex acute, base rounded with eccentric attachment, margin entire to minutely denticulate, hispid on basiscopic half of upper surface; median leaves ovate-lanceolate, keeled-acuminate at apex, base exauriculate, margin minutely denticulate to entire, with white border; axillary leaves ovate-lanceolate, asymmetrical, wider on acroscopic side (similar in size and shape to lateral leaves), exauriculate, margin denticulate only at base, base broadly rounded; strobili 2.3-4.0 mm wide, 6-15 mm long; sp-rophylls dimorphic and of two colors (the upper [median] two ranks green, spreading, the lower [lateral] two ranks nearly colorless and ascending), asymmetric with denticulate margins and with prominent keel; megasporangia in two ventral rows; megaspores light orange to orange, 200270 pm diam., with reticulum of low ridges; microsporangia very small; microspores light orange, with fine reticulum.
Discussion:
Type. Mexico. Oaxaca: Dist. Ixtlán, 7 km S of Vista Hermosa, along stream in wet montane forest, 5400' [1645 m], 23 Sep 1972, Mickel 6735 (NY!; isotypes to be distributed). Resembling S. apoda in general habit and denticulate leaves, S. disticha is distinctive in its hispid lateral leaves, the leaves silvery beneath, orange megaspores, and especially its strongly dimorphic sporophylls, which give a broad, flattened appearance to the strobili. It differs from S. lychnuchus Spring of Costa Rica to Venezuela by its hispid lateral leaf surfaces and the main stems rooting throughout. See S. bernoullii and S. porphyrospora, the other species with hispid lateral leaves and denticulate median leaves, for comparison with S. disticha. The other specimens (NY) examined are from Chiapas (Breedlove 32680, Mun. of Rayón, 1700 m; Gittins 4238B, Puerto Viendo near Rincón Chamula, 1850 m) and Guerrero (Lorea 2998, ca. 2 km SE of El Molote, 1620 m).
Type. Mexico. Oaxaca: Dist. Ixtlán, 7 km S of Vista Hermosa, along stream in wet montane forest, 5400' [1645 m], 23 Sep 1972, Mickel 6735 (NY!; isotypes to be distributed). Resembling S. apoda in general habit and denticulate leaves, S. disticha is distinctive in its hispid lateral leaves, the leaves silvery beneath, orange megaspores, and especially its strongly dimorphic sporophylls, which give a broad, flattened appearance to the strobili. It differs from S. lychnuchus Spring of Costa Rica to Venezuela by its hispid lateral leaf surfaces and the main stems rooting throughout. See S. bernoullii and S. porphyrospora, the other species with hispid lateral leaves and denticulate median leaves, for comparison with S. disticha. The other specimens (NY) examined are from Chiapas (Breedlove 32680, Mun. of Rayón, 1700 m; Gittins 4238B, Puerto Viendo near Rincón Chamula, 1850 m) and Guerrero (Lorea 2998, ca. 2 km SE of El Molote, 1620 m).
Distribution:
Mexico North America|
Mexico North America|