MOSSES. 
195 
callod fronds. The fruit mostly disposed in dots or lines, grows on 
the back, summit, or near the base of the frorid. At Fig. 152, is a 
delineation of some of the various modes in which the fructification 
of ferns appears ; a, is the genus polypodium or polypody, with cap- 
sules in roundish spots on the back of the frond ; 6, asplenium, cap- 
sules in lines nearly parallel, diverging from the centre of the frond 
c, BLECHNUM, capsules in uninterrupted lines running parallel to the 
midrib of the frond on both sides ; d, pteris, or brake, capsules form 
ing lines on the edge of the leaf 
Some ferns bear their fruit in a peculiar appendage, as a spike or 
protuberance in the axils, or at the base of the leaves ; no appear 
ance of flowers in these plants is ever presented. When the brown 
or white dust-like spots are examined with a microscope, they are 
found to consist of clusters of very small capsules, at first entire, but 
afterward bursting elastically and irregularly. Besides attention 
to the situation and form of the capsules, it is necessary to observe 
the membrane which envelopes them ; this is called their involucrum.^ 
The seed i.s as minute as the finest powder, and so hght as to be 
wafted by the air to any distance or height ; we thus often see ferns 
growing high on the trunks of trees, or on the summits of old build- 
ings. Some ferns grow to a great height in southern latitudes, al- 
most like trees. At the southern extremity of Van Diemen's Land, 
a species has been found, whose trunks attained to the height of 
twelve or sixteen feet. One species in our country, Onoclea sensi- 
bilis, called the sensitive fern, is said to wither on being touched by 
the human hand, though the touch of other substances does not pro- 
duce the same phenomenon. 
The number of species of ferns which are already known, amounts 
to about seven hundred. They generally abound in moist and shady 
situations, but are sometimes found on rocks and dry places, and on 
the trunks and branches of old trees. The frond, or leaf of the fern, 
is often pinnate, or divided like a feather ; sometimes it is undivided, 
and resembles a palm-leaf 
The Equisetum hyemale is known to housekeepers under the name 
of scouring-rush. The quantity of silex contained in the cuticle, 
renders it a good substitute for scouring-sand. 
Order Musci, or Mosses. 
The 2d Order contains the mosses, which are little herbs with dis- 
tinct stems ; their conical, membranous corolla is called a cahjptra, 
or veil, its summit being the stigma ; this veil clothes the capsules, 
which before the seeds, called sporules., ripen, is elevated on a foot- 
«italk. The capsule, called theca, is of one cell, and one valve, open- 
mg by a vertical lid ; the seeds are very numerous and minute. In 
some genera the veil is wanting, this serves as a distinction in the 
order. The barren flower of mosses consists of a number of nearly 
cyhndrical, almost sessile anthers ; the fertile flowers have one per- 
fcf.t pistil, seldom more, accompanied by several barren pistils. Both 
stamens and pistils are intermixed with numerous, succulent threads. 
You may here observe (Pig. 153) the different parts of mosses ; a, 
represents the theca; b, the pedicel, or stem ; c, the sheath, which, 
* Also called indusium. The capsules are the thecce ; a collection of them, sori} 
<he seeds are sporules. 
Modes of the fructification of ferns— Sensitive fern — Number of species of ferns— 
Scouring-rush— Mosses— Explain Fig. 153. 
