292 The Ohio Naturalist. [Vol. II, No. 8, 



the plant. Examples are the early Avens, Geum vermin ; and 

 Tooth-leaved Cress, Arabis deutata. 



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. The.se are 

 Plantago aristata and Plantago virginica. Most of the advantages 

 of a ro.sette habit are lost to an annual so that one may well believe 

 that an annual ro.sette 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 leaf}- 

 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 th^ 

 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, Verbascum blattaria, or of the common Tea.sel, 

 Dip.sacus sylvestris, be examined late in October it will be seen 

 that it is pre-s.sed 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 sul)stance ki:own 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 Autunni 

 and Spring. The leaves of a clo.se 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. 

 vSometimes the rosette is pulled down so as to form a small pit, at 



