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230 FERNS OF NORTH AMERICA.
The fertile fronds rise from the root-stock in early spring,
at first densely woolly with light-brown tomentum, and showing
a pretty group of little croziers for each plant; but, when
the frond is fairly uncoiled, the abundant sporangia give it
the characteristic cinnamon-brown coloring. The sterile fronds
soon follow the fertile ones, and, when regularly disposed, form
a magnificent green vase, within which stand erect the rich
plumes of fructification. Normally the fronds are either wholly
sterile, green, and firmly chartaceous, or wholly fertile, soft, and
devoid of green tissue ; but fronds are not rare in which some
of the lower pinnæ are foliaceous, while the greater part of
them are fully fertile. Other fronds are mainly sterile, but
with the apex wholly or partly transformed into fructification.
Such fronds, which are plainly mere accidents, constitute the
var. frondosa of Grays Manual and of Milde’s Monograph.
This condition, rather than variation, occurs also in specimens
from Chiapas, Mexico, collected by Dr. Ghiesbreght. Mr.
W. H. Leggett found still another anomaly in Peekskill, New
York, in which the lower part of the frond is fertile, while the
apex is sterile, and the middle part shows a gradual transition
from one condition to the other. The fertile fronds are usually
as tall as the sterile, though sometimes only half their
height, and rarely overtopping them. The pinnæ are about
two inches long, and, until they wither, stand nearly erect.
They are densely bipinnate, and heavily covered with sporangia,
which are thus described by Dr. Milde: “ The cinnamon-
brown color pervades the whole sporangium : this coloring
FERNS OF NORTH AMERICA.
comes not only from the partition-walls, but from the entire
cell-wall ; and only the ring, as in all the Osmundas, is colored
yellow in the strata of its cell-walls. The ring is four ceils
high, and ten to twelve cells broad. The line of fissure is
bordered on each side by two or three slender rows of cells,
which are not unfrequently much longer than the neighboring
large cells, though always three times as narrow.” The
spores are yellowish-green, globular, and minutely verrucose-
puiictate. If the three vittæ which belong to the genus are
present, I have failed to discover them.
Besides the imperfectly fruited fertile fronds, of which the
vdiV. frondosa has been constituted, there are mentioned by fern-
writers two other varieties.
Var. alata ( H o o k e r , FI. Bor. Am., ii., p. 265; M i l d e ,
Monogr., p. 94) has the rachis slightly wing - margined, — a
not uncommon character of large fronds.
Var. imbricata ( M i l d e ), which is Kunze’s Osmmzda imbricata,
is said to have the fronds rigid and coriaceous, the
pinnæ sub-erect, and the segments imbricated. It is a Brazilian
form, of which I have seen no specimens; but Milde thinks
it passes gradually into the usual form ; and fronds with the
segments more or less imbricated are not rare in the United
States.
All our native species of Osmunda may be easily cultivated
in common garden-soil, and, in fact, are very frequently
seen in the gardens and door-yards of our New-England
towns. But if one will take the pains to prepare for these
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