290 
The Ohio Naturalist. 
[Vol. II, No. 8, 
ROSETTE PLANTS OF OHIO. 
Frederick J. Tyler. 
Among the many forms of vegetation represented in Ohio, the 
rosette is not the least interesting and remarkable. There are 
about 155 species and varieties of plants in the State which ex- 
hibit this habit during some period of their life history and since 
many of them are very abundant and some are classed as bad 
weeds, they form a conspicuous and important part of the flora. 
Rosette plants are characterized by a basal tuft or whorl of 
leaves which may be persistent (perpetual rosettes, as the com- 
mon Dandelion) or may disappear as the plant reaches maturity 
(temporary rosettes, as the Mulleins and most other rosette- 
biennials). This basal tuft of leaves is due to a shortening 
(non-development ) of the internodes of the stem, thus bringing 
the leaves close together. The amount of stem reduction may 
be approximated by counting the number of leaves in a rosette 
and comparing with the number of leaves on a flowering stem of 
the same plant. The stem forming the central axis of the rosette 
of Onagra biennis, the common Evening Primrose, will be found 
to bear 50 to 70 times as many leaves as the same space of flow- 
ering stem. In other words a stem length of 13 to 17 in. has been 
shortened to in. 
The advantage of the rosette habit is chiefly in the protection 
which it affords from extremes of temperature and from drying 
winds, browsing animals, etc. The typical rosette rarely projects 
more than an inch or so above the ground and the leaves are usually 
spread out flat upon the surface. In Winter the rosette is well 
protected by even a light blanket of snow and is often partially 
covered by the debris of higher vegetation which has been cut 
down b} r frost. 
In this latitude the majority of rosette plants are biennials, 
that is, plants which complete their life cycle in two years, 
spending the first year in getting a foothold, establishing a strong 
root system, and usually in storing up some reserve food material. 
The next year they start out vigorously on their lifew’ork of pro- 
ducing seed. It is easily seen that the rosette habit is peculiarly 
adapted to the needs of a biennial during its first year’s growth. 
It is compact, well protected for the Winter and the preservation 
of reserve food material is made easy. But for the all important 
work of the second year the rosette is not at all adapted. Now 
it is too compact, 011I3' a limited amount of foliage can be borne 
by the short stem, and not enough space can be given to the pro- 
duction of flowers and fruit. So the biennial abandons the rosette 
habit at the beginning of the second growing season and grows 
up into a tall, branching herb. Familiar examples are the Turnip, 
