64 BOTANY, 
during the wet season. Lycopodium clavatum, or common club-moss (pl. 54, 
jig. 58.) 
OrvER 7. Marsiteace®, ok Ruizocarrem, the Pepperwort Family. 
Stem wanting, or a rhizome. Leaves often stalked, with the lamina 
divided into three or more wedge-shaped pieces. Sometimes the lamina is 
abortive ; vernation circinate. Reproductive organs near the root, or along 
the petiole, inclosed in an involucre; these organs are of two kinds: 1. 
Stalked or sessile clustered membranous sacs, containing minute granules, 
which some consider as pollen: hence the bodies are called anthers. 2. 
Membranous sacs, containing cells which divide into four, one only of which is 
developed as a germinating body; the sacs have been called ovule-sacs, and 
the single developed cell is considered by some as an ovule which is impreg- 
nated by the so-called pollen. The thece are the bodies from which 
germination proceeds, creeping or floating plants, found in ditches and pools 
in various parts of the world, more especially in temperate climates. They 
are not put to any important use. There are four genera, and upwards 
of twenty species. Examples: Marsilea, Pilularia, Salvinia. Marsilea 
quadrifolia (pl. 54, fig. 47); Pilularia globulifera (fig. 45); Salvinia natans 
(pl. 54, fig. 46). | 
OrpeR 8. Finices, or Ferns. Stem a rhizome, which creeps along or 
under the surface of the ground, emitting descending roots and ascending 
fronds (leaves), or which rises into the air so as to form an acrogenous 
trunk. This trunk (stipe) 1s of nearly uniform diameter, is hollow in the 
interior, marked on the hard outer rind by the scars (cicatrices) of the 
leaves, and contains vascular bundles of woody, dotted, and scalariform 
vessels, which are inclosed in hard plates, and are arranged in an irregular 
manner. Sometimes the trunk is dichotomous. The outer fibrous 
covering is formed by the bases of the leaves, and is thicker at the lower 
than at the upper part of the stem. The leaves (fronds) have a circinate 
(gyrate) vernation; their veins are generally of equal thickness, and either 
simple or dividing in a forked manner, or somewhat reticulated, and 
occasionally stomata occur. Reproductive organs consisting of spore- 
cases (thecze, sporangia), which arise from the veins on the under surface 
of the fronds, or from their margin. Spore-cases either stalked, with the 
pedicel passing round them in the form of an elastic ring, or sessile and 
destitute of a ring. The theca sometimes arise from the surface of the 
frond, while at other times they spring from below, having a cuticular 
covering in the form of an indusium or involucre. The clusters of thecz 
are called sori. The margin of the frond sometimes is folded so as to cover 
the thecz, and at times the whole frond is converted into clusters of 
thecee. Certain cellular papilla, on the margin or upper surface of the 
fronds, have been considered by some as antheridia, each of the cells 
containing a spiral fibre. Link and others state, that among the young 
thecee (pistillidia) filamentous bodies occur, which are equivalent to 
stamens. Ferns are elegant, leafy plants, occurring chiefly in moist 
insular climates, and abounding in the tropical islands. In mild and warm 
climates they occur in the form of large tree-ferns, fifty to sixty feet 
64 
