292 
The Ohio Naturalist. 
[Vol. II, No. 8,. 
the plant. Examples are the early Aveus, Geum vernun ; and 
Tooth-leaved Cress, Arabis dentata. 
Under less favorable conditions the perpetual rosette is more 
abundant. In dry, tropical deserts, for instance, a certain special- 
ized form of the rosette is very common. This is the succulent 
leaf type (Agave, Echeveria, Sempervivum, etc.) Also in Alpine 
and Polar regions the perpetual rosettes occur in great numbers. 
A few annuals form a small and imperfect rosette soon after 
sprouting from the seed and before they send up an aerial stem, 
and at least two annuals in our Flora are acaulescent. These are 
Plantago aristata and Plantago virginica. Most of the advantages 
of a rosette habit are lost to an annual so that one may well believe 
that an annual rosette plant was once longer lived than it is now. 
Rosettes may be termed open or close when the leaves are 
loosely arranged, as with the Cranesbill, Geranium molle ; or 
crowded, as with the Evening Primrose, Onagra biennis. In a 
few cases the rosette is not basal but is located at the end of a leafy 
stem of some length as with the common sedum, Sedum terna- 
tum. Rosettes of leaves are formed three or four feet above the 
ground, on the end of stems of Polymnia canadensis, and are 
brought down close to the surface in Autumn by the reclining 
stems. In this latitude, however, they do not survive the 
Winter. 
Rosette plants exhibit some interesting adaptations for pro- 
tection from cold, such as the geotropic curvature of the leaves 
and the development of red color. If a leaf of a rosette of 
Smooth Mullein, Yerbascum blattaria, or of the common Teasel, 
Dipsacus sylvestris, be examined late in October it will be seen 
that it is pressed tightly against the surface of the ground, and if 
the entire plant is dug up and placed in a collecting case for a few 
hours the leaves will be found turned downwards so far that they 
are parallel with the tap root and form a cup around it. During 
the same season of the year the leaves of many rosette plants are 
quite red or purple. This is due to a substance known as antho- 
cyan. It is the same red coloring matter that is present in the 
unfolding leaves and twigs of Red Maple, Acer rubrum, and Soft 
Maple, Acer saccharinum. Anthocyan changes some of the rays 
of light, which pass through it, into heat and is of much impor- 
tance in the economy of the plant during the cold days of Autumn 
and Spring. The leaves of a close rosette are often arranged very 
nicely to prevent the lower being shaded. This is accomplished 
by a spiral arrangement and by the elongation of petioles of lower 
leaves. 
It might be expected, in case of perpetual rosettes, that the 
plant would gradually grow out of the ground but this is coun- 
teracted by a shortening of the roots which pulls the plant back. 
Sometimes the rosette is pulled down so as to form a small pit, at 
