Definition of Sphenopsida
: a subdivison of Tracheophyta comprising vascular plants (such as the horsetails and extinct related forms) with jointed stems, small leaves usually in whorls at distinct stem nodes, and sporangia in sporangiophores and including the orders Hyeniales, Sphenophyllales, and Equisetales — compare lycopsida, psilopsida, pteropsida
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Origin and Etymology of sphenopsida
New Latin, from sphen- + -opsis + -ida
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