200 



IIISTOllY OF THE VEGETABLK KINGDOM. 



they are very small globular, tripjonal or reni- 

 fonn, unilocular capsules, containing a great 

 number of very small sporules. Sometimes 

 these capsules are a little larger, open into two 

 or three Viilves, and contain only three or four 

 sporules of a large size. These two species of 

 capsules, which may both occur on the same in- 

 dividual, are sometimes axillar and solit.iry, 

 sometimes aggregated in the axil of bracteas, 

 and then foiTn simple or digitate spikes. 



The genus Li^zopodium, which forms the type 

 of this family, was placed by Linnteus among 

 the musci, and by Jussieu among the ferns. 

 But the organization and position of the repro- 

 ductive organs easily distinguish the lycopodia- 

 ccte from these families. 



The powder contained in the capsules of It/- 

 copodium clavatum and sclago is very inflamma- 

 ble, and has been used in fireworks. No species 

 of this family seems to be of any importance 

 in an economical point of view. 



Ferns are herbaceous perennial plants, some- 

 Umes becoming arborescent in the tropical re- 



Tree Feni. 



giong, and then rising in the manner of palms. 

 Their leaves or fronds are sometimes simple, 

 sometimes more or less deeply cut, pinnatifid 

 or decompound. These fronds present a common 

 character, that of being rolled up like a crosier 

 at their extremity, at the period when they be- 

 gin to be developed. The organs of fructifica- 

 tion are commonly situated on the lower surface 

 of the leaves, along the nerves, or at their ex- 

 tremity. The sporules are naked or contained 

 in a kind of small capsules. These capsules are 

 aggregated into little masses, which are named 

 tori. Tliese sori are in the form of round kidney- 

 shaped, sessile or stipitate scales, sometimes sur- 

 rounded by an elastic ring, opening either at 

 their circumference, or by a longitudinal slit, or 

 bursting irregularly. In the genus Pteris, the 

 sporules are placed under the replicate margin 



of the leaves, which fonns an xmintemipted 

 line. In the species of adiantum, they consti- 

 tute small prominent and isolated plates, by 

 means of the replicate margin of tlie leaves. In 

 certain genera they are isolated, while in others 

 they are aggregated, and fonn more or less elon- 

 gated lines. The sori begin to be developed 

 under the epidermis, which they raise in such a 

 manner as to bo covered by it. The portions of 

 epidermis which thus form a covering to the 

 sori are named indusia. In some ferns, such as 

 the osmundce and ophioglossa, the fnictifications 

 are disposed in clusters or spikes. 



The genera of ferns at present knoAvn are very 

 numerous, and form five natural sections: 



1. Polt/podiaceoe. — Capsules free, bursting in 

 an iiTegular manner, surrounded by a narrow 

 and prominent elastic ring, which terminates in 

 a pedicle of greater or less length, as joo^jpodiuffs, 

 aspidium, asplcnium, pteris. 



2. Gleicheniae. — Capsules free, sessile, regu- 

 larly arranged in a small number of groups, 

 surrounded at the middle by a broad and flat 

 elastic ring, opening by a transverse slit, as cera- 

 topteris, gleichenia, mertensia. 



3. Osmundacece. — Capsules free, opening by a 

 longitudinal slit into two valves; no elastic ring: 

 or, instead of one, a striated cup, as anemia, ly- 

 godium, osmunda. 



4. Marattieoe. — -Capsules sessile, aggregated, 

 and united, so as to represent a many-celled 

 capsule; no elastic ring, as danaea and marattia. 



6. The Ophioglossece. — Capsules free, partly im- 

 mersed in the frond, without elastic ring, and 

 opening by a transverse fissure, as ophioglossum, 

 botrychium. 



Authors have varied much as to the nature of 

 the reproductive organs in ferns. Almost all 

 have considered the capsules as female organs. 

 But some, as Micheli and Hedwig, have consid- 

 ered as male organs the glandular hairs which 

 are sometimes seen on the young leaves. Others, 

 with Hill and Schmidel, have called the rings of 

 the conceptacles, stamina; and, lastly, others 

 have given this name to the miliary glands and 

 indusia. 



Several species of fern have been employed as 

 food, such as ptesis csculonta, diplagium eaculen- 

 tum, and nephrodium esculentum. The leaves of 

 many species are mucilaginous, with a slight 

 astringency, and some aroma. They have ac- 

 cordingly been used as expectorants. Poli/podittm 

 calaguala and crassifolium are said to be medi- 

 cinal, but are now rarely or never used. The 

 stems of other species being bitter and astringent, 

 have been used as anthelmintics. Aspidium 

 fiUx-mas, A. filix-fosmina, and pteris aquilina, 

 have been thus employed. 



Eqdiseta or Horse-tail. This small family 

 is composed of the single genus Equisetum. All 

 the species are herbaceous, perennial plants. 



