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144 F E R N S O F NORTH AM E R IC A .
apex, and strongly serrated throughout. The texture is thin
but firm, chartaceous, or coriaceo-membranaceous as described
by Hooker. The veins are about one-third of a line apart,
and leave the midvein nearly at a right angle. Many of
them are simple, and others, mixed in irregularly with the
simple ones, fork either near the base, or half way to the
margin. The very edge is semi-translucent and sub-cartilag-
InoLis, the acute serratures partaking of this character. In
this firm and semi-translucent edge is perhaps the readiest
distinction between this fern and the nearly related Pteris
serruiata, which, though long a garden fern of unknown
origin, has now for some years been considered a native of
China, but has recently been discovered wild, and apparently
native, near Mobile, and has also been growing without
cultivation, on the walls of the college at Charleston,
South Carolina, for many years.
The fertile fronds of Pteris Crética have linear pinnæ
three to six or eight inches long, and three or four, rarely
five or six, lines wide, nearly linear in shape, the margin
entire, and bordered with a delicate continuous recurved involucre,
and the apex for the distance of an inch or more
very sharply spinulose-serrate.
The sporangia are borne on a continuous marginal
veinlike receptacle, and are covered by the involucre until
near maturity. The ring of the sporangia consists of about
twenty-one joints. The spores are roundish-tetrahedral, plainly
trivittate, and have a faintly sculptured surface.
J
F E R N S OF NORTH AM E R IC A . 145
This fern receives its specific name from the island
of Crete. Whether it was first discovered there I cannot
determine: Swartz says “ Europa australis, Oriens;’’ Willdenow
indicates Switzerland, Italy, Corsica, Crete and Arabia.
A very full list of Old-World localities may be seen in
Hooker’s Species Filicum, where there is also a var. sten-
ophylla, in which the fronds are digitate or sub-pinnate,
and the few pinnæ entire or nearly so. This form occurs
in Northern India, and in the Philippines, and is figured
by Hooker and Greville {Ic. EH., I. 130). Another variety
is noticed in Synopsis Filicum, var. melanocaulon, having a
dark-colored stalk and scarcely visible venation : this form
was found long ago in the Philippines by Cuming, and
is described and figured as a species by Fée {yme Mém.
p. 31, t. x ix , fig . i). A common form in cultivation is
var. albo-lineata, in which there is a broad whitish stripe
on the upper surface along the middle of each pinna.
The pale color is apparently due to a partial deficiency
of chlorophyll in the cells just beneath the epidermal layer,
and also to a paler color in what chlorophyll there actually
is there. This form has been figured in Curtis’s Botanical
Magazine (t. 5194), and in one or two other places.
Mr. Baker reports that it has been found in Brazil by
Dr. Glaziou.
Pteris fiellucida, P . Hookeriana and P. dactylina, all
F ast Indian ferns, are closely allied to P. Crética, and by
some authors are regarded as doubtfully distinct from it.
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