FERNS AND MOSSES. I§1I 
A sporangium when examined under the microscope (fig. 64) 
is seen to be a stalked capsule round the margin of which runs 
a curiously thickened band, the annulus. Within the capsule 
numerous small spores can be seen. 
The roots of bracken (fig. 63) are brown branching threads 
BURNER 
SS 
ES INAeR 
DHL ON EEE? 
SAS 2) > 
Fic. 64.—Sporangia of male fern, much enlarged (from Sachs). A. Section through a 
sorus, showing sporangia s, s. of various ages, covered by indusium 7,7. B. Young 
sporangium as seen in section; the shaded cells in its interior divide up to produce 
spores. ©. Mature sporangium in the interior of which spores are seen; 7, 7. 
annulus. 
growing out from the rhizome and the bases of the leaf-stalks. 
They are similar in appearance in the male fern, where, however, 
they are developed in the latter position only. 
Structure of the sporophyte (fig. 63, D, E, H). By cutting across the 
rhizome of the male fern a ring of small vascular bundles can easily be 
seen. These are imbedded in a large amount of ground-tissue divisible 
into a central pith and a peripheral cortex. At the margin of the latter 
is a narrow band of brown sclerenchyma. In bracken there are two 
concentric rings of bundles separated by sclerenchyma, a broad band 
of which is also present just below the epidermis. Examination of a 
section under the microscope shows that the bundles contain no cambium, 
a.e., are closed, while the wood is completely surrounded by the bast, 
which mode of arrangement is said to be concentric. The leaves of ferns 
are similar in structure to those of flowering plants (fig. 64). 
OOPHYTE (Gametophyte). 
The spores of a fern are liberated from the ripe sporangium 
by the elasticity of the annulus, which tears open the capsule. 
