|
|
Plant Rosettes
Nature Bulletin No. 662 January 13, 1962
Forest Preserve District of Cook County
John J. Duffy, President
David H. Thompson, Senior Naturalist
PLANT ROSETTES
In winter our landscape is mostly leafless trees silhouetted against the
sky, and the dead stalks of wildflowers, weeds and tall grasses -- with or
without a blanket of snow. Some snows lie on the ground for only a few
days. Others follow one after another and cover the ground with white
for weeks at a time. Soon the eye begins to hunger for a glimpse of
something green and growing. Then, in sunny spots where the snow has
melted or where youngsters have cleared it away, there appear clusters
of fresh green leaves pressed tight to the soil.
Whether it is a dandelion in the lawn, a pansy in a flower border, or a
thistle in a vacant lot, such a typical leaf cluster -- called a winter
rosette -- is a ring of leaves around a short central stem. The leaves are
narrow at the base, wider toward the tip, and spread flat on the ground
with little or no overlap. This arrangement gives full exposure to
sunlight and close contact with the warmer soil beneath. Such plants
continue to grow, sometimes faster, sometimes slower, even under
snow, throughout winter.
Each kind of plant seems to have a calendar of its own. There is a time
for growing tall, a time for flowering, and a time for scattering seed.
Among those herbaceous plants that live over from one year to the next
-- biennials and perennials -- the winter rosette is especially suited for
temperate climates. In its first summer a biennial such as a wild carrot
or an evening primrose grows a rosette of leaves from a seed. This lives
over winter, shoots up a tall stalk the next summer, blooms, ripens seed,
and then the whole plant dies. In many perennials, for example the
hollyhock and common plantain, the flower stalk dies as the days grow
shorter but the underground parts and a rosette of green basal leaves
live on until the following year when, again, they flower and set seed.
In our region the winter rosette habit of growth is scattered through
many families of flowering plants and over many types of environment.
Almost all of them are viewed in different ways by different people,
depending on where they grow and on our personal likes and dislikes.
By and large, the majority of them thrive in poor soils and in waste
places where they furnish ground cover and aid in breaking up and
enriching the soil. With their hardy underground parts they survive
fires, floods, trampling and grazing.
The rosettes of dandelion, plantain and buckhorn are merely lawn pests
to most people. However, some of us enjoy a mess of dandelion greens
in spring. In farmers' pastures, grain fields and hay fields a few of these
winter rosettes followed by their tall summer stalks are noxious weeds.
Cattle, sheep and horses refuse to eat spiny thistles and teasel, the fuzzy
mullein, or the ill-flavored wild carrot also called Queen Anne ' s lace.
But, on roadside s, old fields and waste places their bold flowers add
welcome color. In autumn, when dead and brown, they are picked for
winter bouquets.
Strawberries come from rosettes which are cultivated by the thousands
of acres. Smaller in size but full of flavor, ripe wild strawberries abound
in the forest preserves each June. The tender leaf clusters of winter
cress or yellow rocket make a salad that tastes the same as its near
relative, the water cress.
Our wildflower season is ushered in by the blooming of the hepatica,
usually before the last snows of spring. Its delicate white, lavender or
pale blue flowers on their furry stems push up from a winter rosette of
three-lobed liver-colored leaves. On the other hand, the blooming
season is closed, often after autumn snows have begun to fly, by the
purple flower spikes of a little mint called heal-all which also arise from
a ring of basal leaves.
To return to the Nature Bulletins Click Here! |
|
Update: June 2012
|
|
