HEMESTHEUM THELYPTERIS.
MARSH
FEEN,
123
(one-ninth the natural size).
Genus.—HEMESTHEUM. Midvein of pinnules distinct; late­
ral veins alternate, always forked soon after leaving the midvein, and both branches running in parallel lines to the
margin: each bears a cluster of capsules near the fork, and
these being equidistant from the midvein and the margin, form
two continuous series, which are concealed by the convolute
margin of the pinnule : involucre minute, indistinct, subreniform, evanescent : each first upper and first lower pinnule