THEIR FORMS AND FUNCTIONS. 527 
and a small portion of its own leaf. The stipules of the leaf 
still closely applied to the bud protect the latter, including their 
own leaf. 
In the Alder (Alnus glutinosa, Gaertn., var. laciniata, Ait.) the 
stipules are oblong, obtuse, entire, 7~9 mm. long, deciduous, or 
falling away much sooner than the leaves, and therefore almost 
caducous, membranous, but subfoliaceous. They are of service 
in protecting the young leaves of the elongating shoots in summer, 
and also the axillary buds Jater on when they begin to develop. 
They are evidently more serviceable in protecting the winter- 
bud, of which they constitute the enveloping and protecting 
scales, as in the case of the Oak, Beech, &c. There are two or 
three pairs of them without leaves, succeeded by two or three 
which do not attain perfect development. About two pairs 
without leaves are produced, and each pair is wrapped round the 
bud, almost completely covering it. Where leaves are also pro- 
duced, the stipules lie inside the leaf to which they belong. 
All are glued or gummed together by means of the resinous 
or gummy matter exuded by the glands copiously produced all 
over the surface of stem, leaves, and stipules. 
In Ostrya carpinifolia, Torr. et Gray, the buds are ovoid, 
becoming oval or oblong as they elongate in spring, and laterally 
subcompressed. They are made up of, or are protected by, about — 
seven pairs of stipules arranged in four ranks. The leaves when 
expanded are alternate and distichous, so that the stipules, pro- 
tecting the bud and having no leaves of their own, are so arranged 
that the two from one leaf do not strictly overlap the two from 
the next younger leaf. In this way they are placed in four 
instead of two ranks. The Oak has only five ranks of stipules, 
although the leaves are arranged on the ? plan, the reason being 
that each rank is made up of stipules from two ranks of leaves. 
The divergence of the stipules from one rank of leaves in Ostrya 
is not great, however, 80 that of the four rows there are two 
contiguous pairs of rows, one on each side of the stem. All the 
stipules are firmly held together by a gummy material. After 
the seventh pair of stipules comes a perfect leaf folded over the 
bud, which thus prevents it from being conduplicate. The leaves, 
moreover, are slightly plicate in an ascending direction, following 
the course of the lateral nerves. 
