894 
ORYPTOGAMIA MARSILEACE^. 
Class XXIV. 
Order 4. 
MARSILEACE^. 
Reproductive organs radical, uniform. Sporules contained in roundish one or many-celled indehiscent heads. 
Plants simple, aquatic. 
Very few plants are found in this order. Their vegetation is various ; they are at most a few inches high, 
and are more or less aquatic. In Isoetes the leaves resemble those of a young rush. The organs of repro- 
duction are always near the root, and are variable, and their nature is by no means understood. In Pilularia (a) 
it consists of a roundish head, divided internally into 1-4-cells, each cell containing small bodies of two kinds. 
In Isoetes (6) the fructification is even less known and understood. 
2214. Isoetes. Head membranous, not opening, immersed in the base of the frond, 1-celled. Sporules 
angular, inserted upon many filiform receptacles. 
2215. Pilularia. Heads imbricated, solitary, nearly sessile, globose, coriaceous, 4-celled. Cells containing 
two kinds of bodies. 
2214. ISOE'TES. L. 
14648 lactistris W. 
ms. PILULA'RIA. L. 
14f)49 globulifera W. 
QUILLWORT. 
marsh 
PiLLWORT. 
Pepper-grass 
^ A cu 
Jt>. A cu 
Sp. 1—2. 
I my.o Br 
' Sp. 1. 
i jn.s Br 
Britain al.lak. D p.l Eng. bot. 1084 
Britain moi.h. D p.l Eng. bot. 521 
History, Use, Propagation, Culture, 
2214. Isoetes. From la-ei, equal, and era?, the year ; a plant which remains the same through all the 
seasons. A very curious little submersed aquatic, which grows at the bottom of some of the Scotch lakes. 
The leaves are long and cylindrical, whence the English name Quill-wort. 
Order 
MUSCI. 
Reproductive organs of 2 kinds. Theca many-seeded, solitary, furnished with an operculum and columella. 
Plants leafy. 
Mosses are distinguished from all other similar plants, by the peculiar nature of the reproductive organs, which 
are of two kinds. The principal and the most obvious is a theca {a, b), which is furnished with an operculum or 
lid (c), by means of which the sporules are retained in the theca, and a columella, or central axis, to which they 
are attached. The other consist of minute spherical pedicellated organs, concealed in the axils of some of the 
leaves, and called anthers by Hedwig. The theca is either entire, or split into four valves, as in Andrea;a ; 
when in a very young state it is enclosed in an indusium, which is torn asunder as the theca is elongated, and 
being carried up with it, remains upon the summit of the theca in the form of a little extinguisher called 
