Definition of Psilopsida
: a subdivision of Tracheophyta comprising vascular plants with no roots, leaves only partially differentiated or lacking, no leaf traces, a usually protostelic vascular cylinder, and the sporangia merely terminal enlargements of the stem — compare lycopsida pteropsida sphenopsida
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Origin and Etymology of psilopsida
New Latin, from psil- + -opsida (as in lycopsida)
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