276 THE VEGETABLE WORLD. 
attained a height of forty or fifty feet their stems form a noble 
column, some five or six inches thick, from the summit of which 
flows a panicle of pinnate leaves intersected by a thousand incisions, 
the terminal tuft which crowns the summit of the trunk curving at 
all times into a sort of cross, whose graceful curve adds greatly to 
the elegance of the tree. Their chief anatomical peculiarities are 
as follows :— 
The leaves are termed Fronds, and they bear the organs of 
fructification in little cups or receptacles on the edges, or on the 
under surface, in the form of little masses of granules, termed sori, 
consisting of a containing organ termed sporangia, theca, or cap- 
sules, surrounded by a ring termed gyrus, or annulus, and a number 
of contained cells termed spores, or sporules, from which the new 
plant is produced. The foot-stalk of the leaf or frond is called a 
stipe, and. consists of bundles of bare woody fibre and scalariform 
vessels, connected together by cellular tissue, which pass down 
into the stem under the bark, forming the zones of the wood. In 
the Tree Fern the rind or bark consists of one or two layers'of 
_ Fig. 337.—Stem and section of a Tree Fern. 
cellular tissue, and is marked from top to bottom by the cicatrices 
left by the fallen leaves (Fig. 337, a). These cicatrices occur 
irregularly and at considerable distances apart near the foot of the 
tree, but at regular distances and almost close together towards cap 
summit of the stem, showing that its leaves are produced at the 
top and in successive clusters, and that the trunk has inereased ™ 
height after the fall of the leaf. Again, a large portion of the 
transverse section of the trunk is seen to consist of cellular tiss¥°? - 
