34 Maidenhair 
bearing at apex two pinne and, except in very small leaves, on 
upper side about two to twelve radiating pinne interspersed 
with single pinnules, a single pinnule also borne on rachis below 
one of basal pinnz: pinne lanceolate or linear-lanceolate or the 
smaller oblong or suboval, obtuse, pinnate, the basal six to ten 
inches long, the outer successively shorter: pinnules numerous, 
two-fifths of an inch to one inch long, alternate, stalked, oblong or 
oblong deltoid, the apical cuneate, the lower mostly becoming cu- 
neate or transversely oblong, attached at acute lower corner, other 
corners rounded; entire on sides next footstalk, otherwise dentate 
and on upper side or both upper and outer sides cut into oblong 
often oblique lobes; apical pinnules, and outermost basal pinnules 
of outermost pinnz, sometimes bifid: surfaces glabrous; the 
upper repelling water, bright green or darker; the lower paler; 
texture elastic, membranaceous. 
Venation conspicuous, free: principal vein of each pinnule 
dividing at base of pinnule into two branches: in oblong or 
deltoid-oblong pinnules, the outer branch forming a unilateral 
midvein next pinnule’s lower margin, bearing branches on upper 
side; the inner branch appearing as basal primary branch of 
the outer, little, if any, more complex than primary branch next 
it: in cuneate or transversely oblong pinnules both branches 
forming unilateral midveins, one each side of pinnule’s footstalk, 
next pinnule’s margin, bearing branches on upper side: primary 
branches of midvein three to four times forked at midvein’s 
base diminishing to once-forked or simple at midvein’s apex, 
pinnule’s lobes each occupied by one. 
Sori borne at apices of veinlets on under side of indusia: 
indusia consisting of reflexed altered portions, chiefly ends of 
lobes, of pinnule’s upper margin, transversely oblong or linear 
