sīˈläpsədə noun plural
Usage: capitalized
Etymology: New Latin, from psil- + -opsida (as in lycopsida )
: 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