ii. 'i
lift
in which it may grow; but, on a careful examination of numerous
specimens of these varieties now before me, I cannot fix on any
characters which appear of specific value. My friend Mr. Hore
finds that the utricles or spores of the small variety which commonly
grows on Desmarestia aculeata are borne on little stalks,
while in the common form represented in our plate they are
mostly sessile; and this character, were it constant, would afford
a readily appreciable mark of distinction. But when making
the sketch for the magnified ramulus (fig. 4) taken, without
selection, from a specimen of the common form, I observed that
though the spores are often nearly sessile, there is frequently a
short pedicel. And when any disposition to form a pedicel exists
in so variable a plant as this, its amount must be most uncertain.
The spore is to be regarded morphologically as an abbreviated
ramulus; where the whole ramulus is converted into a
spore, that organ will be sessile; but when a part only is so
changed, it will be stalked.
This species was once confounded with S. plumosa, but differs
from that beautiful plant in habit and size, iu its jointed main
filaments, and in being far less regularly pectinato-pinnated,
with proportionally shorter pinnules. Being a very common
plant, it was among the first of the genus observed by botanists,
and is figured in the Historia Muscorum of Dillenius, under the
specific name here preserved. By Hudson it was subsequently
called pennata, a name adopted by succeeding authors until the
older one was restored by B,oth.
i I ' :
Pig. 1. Sph acela eia o iek h o sa ; tufts :— o/ the natural size. 2. Part of the
stem and pinnated branches. 3. Apex, of a branch with ramuli. 4.
Kamnlus with utricles.
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