Equisetum hyemale L. x E. myriochaetum Schltdl. & Cham.
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Authority
Mickel, John T. & Beitel, Joseph M. 1988. Pteridophyte Flora of Oaxaca, Mexico. Mem. New York Bot. Gard. 46: 1-580.
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Family
Equisetaceae
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Scientific Name
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Description
Species Description - Stems tall, unbranched to irregularly and sparsely branched or much-branched, to 2.5 m tall, 3.5-8. 5 mm diam., with 14-36 ridges; stem sheath with length to width ratio of 1:1.7; lower sheaths with two dark bands and ashen gray between, upper sheaths with single marginal band and same color as stem; teeth mostly deciduous; branch ridges with irregular to saw-toothed tubercles; strobili strongly apiculate, with abortive spores.
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Discussion
According to Hauke (1963), all specimens of this combination come from the region of parental overlap, in Mexico and Guatemala. The hybrid has abortive spores, lacking contents and elaters. The nodal sheaths resemble those of E. hyemale near the base and those of E. myriochaetum towards the tip and distinguish both branched and unbranched stems.
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Distribution
Infrequent in wet ditches and seepage areas about the state; Centro, Ixtlán, Juquila, Tlacolula, Villa Alta; 750-2250 m. Mexico (Mich, Gro, Mex, NL, SLP, Ver, Pue, Oax); Guat. Oaxaca collections: 775, 859a&b, 1420, 5958, 6095; Camp 2570 (NY); Hallberg 1020 (MICH); Kenoyer 1580 (GH).
Mexico North America| Michigan United States of America North America| Guatemala Central America|