PELLAEA GLABELLA AND ITS SEGREGATES 77 
foliolate (very rarely 5-foliolate). In such pinnae the 
middle pinnule is twice as long as the lateral ones. In 
semi-compound pinnae the basal pinnules are commonly 
represented merely by basal auricles, which, in marked 
contrast to P. glabella, are frequently found on both 
sides of the pinna. Even when compound, the basal 
pinnae are often smaller than the second pair, and they 
frequently wither early, so that in many specimens only 
their petiolules remain. This characteristic tends, of 
course, to conceal the twice pinnate character of the 
fronds in many cases. 
In P. pumila the fronds of the smaller specimens are 
usually strictly once-pinnate. Those of larger specimens 
have one or two pairs of nearly compound 2-3-foliolate 
pinnae. In these the terminal pinnule is not distinctly 
stalked, but is narrowed at the base, which is confluent 
with the one or two lateral pinnules, which are less than 
14 as long as the terminal one. The anterior basal 
pinnule is often better developed than the posterior, and 
unilateral (mitten-shaped) pinnae are very common. 
The basal lobes are very rarely reduced to auricles. 
Though somewhat variable, the shape of the simple 
pinnae is characteristic in each species. In P. glabella 
they are oblong-linear, rarely somewhat lanceolate, 
obtuse and pseudomucronate‘ or somewhat acute at the 
apex, and often cordate atthe base. The lower ones 
have stalks about 0.5 mm. long. In P. Suksdorfiana 
they are lanceolate or oblong-lanceolate, obtuse or some- 
what acute and rarely pseudomucronate at the apex, 
and cuneate or narrowed to the base. The lower ones 
have stalks 1-2 mm. long. In P. pumila they are ovate 
(rarely elliptical, ovate-lanceolate, or lanceolate), obtuse 
at the apex, and truncate or abruptly cuneate at the 
base. All are sessile, or the lowest may have very short 
stalks, less than 0.5 mm. long. 
ed by the straight tip of the leaflet, while 
17T ‘ ‘ 
he apparent mucro is form ay taded ia te baci wack ot te 
on each side of the tip the margin is abrupt 
indusium 
