MOSSES. 195 



called /?-o?i(Zs. The fruit mostly disposed in dots or lines, grows on 

 the back, summit, or near the base of the frovd. 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 ; b, asplenium, cajv 

 sules in lines nearly parallel, diverging from the centre of the frond ; 

 r, ELEOHNUM, capsulcs 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 is 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 

 tlie 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 EauisETUM 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 Musr.i, or Mosses. 



The 2d Or^der 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 spontles, ripen, is elevated on a foot- 

 'Jtalk. The capsule, called theca, is of one cell, and one valve, open- 

 ing by a vertical Ud; the seeds are very numerous and minute. In 

 some genera the veil is wanting, this serves as a distinction in the 

 order. The barren fiower of mosses consists of a number ofnearly 

 cylindrical, almost sessile anthers; the fertile flowers have one per- 

 fect pistil, seldom more, accompanied by several barren pistils. Both 

 stamens and pistils are intermixed with numerous, succulent threads. 

 You may here observe (Fig. 153) the different parts of mosses ; a, 

 /epresents the theca ; b, the pedicel, or stem ; c, the sheath, which, 



* Also called indusium. The capsules are the theccB ; a collection of them, sori; 

 the seeds are spoi-ules. 



Modes of the fructification of ferns— Sensitive fern— Number of species of ferns- 

 Scouring-rush— Mosses— Explain Fig. 153. 



