THEIR FORMS AND FUNCTIONS. 505 
by the fission of one or by the stipule from each leaf being 
perfectly developed. 
The stipules of the aerial leaves are somewhat smaller. 
CoMPposIT Zz. 
In Achillea Millefolium, Linn., and the other species examined, 
the petioles are dilated at the base. In Chrysanthemum also the 
buds are protected by the dilated bases of the petioles, which 
have sometimes a more or less developed membranous margin, 
and in some species of the genus small free auricles. In O. par- 
thentfolium, Pers., the leaves are also frequently furnished with a 
small foliaceous segment on each margin near the base, and re- 
sembling stipules. Occasionally other small scattered segments 
intervene between the basal ones and the lamina proper. They 
may therefore be regarded as segments of an originally sessile 
leaf. In C. sinense, Sabine, also the petioles are auricled in a 
manner much resembling stipules. 
Barnadesia rosea, Lindl., has two thorns at the base of the 
leaf-stalk. Stipule-like auricles occur in Senecio, Trixis, Jungia, 
and other genera. 
DIAPENSIACER. 
Diapensia lapponica, Linn.—The terminal bud is deeply sunk in 
the centre of the small rosette of leaves. The sheathing, imbri- 
cate bases of the leaves form a cylinder round it. When the 
young leaves commence to develop, they do so alternately, and 
two of them cover over the top of the younger members. There 
are no scale-leaves, as the terminal bud is continuous, but becomes 
arrested during the winter season. 
The axillary buds are well protected in their early stages by 
the sheathing portion of the leaf, which is one-third to one-half as 
long as the lamina. 
This type is similar to what occurs amongst many of the species 
of Sawifraga of dwarf and densely tufted habit. . 
In Shortia galacifolia, Torr. & Gray, the petioles are dilated at 
the base. The terminal bud in the resting stage is covered with 
numerous concave, glabrous, red scales, surrounded by a few 
very much reduced leaves of the previous season. The scales 
evidently represent the dilated base of the petiole. 
Schizocodon soldanelloides, Sieb. & Zuce., bas much shorter 
petioles; but otherwise the arrangement is similar. 
