THE DANDELION IN COLORADO 
By B. O. LONGYEAR 
Dandelions everywhere! They spring up along ditch banks, 
crowd into open places in alfalfa fields, or luxuriate in gardens 
and flower-beds. They swarm over vacant city lots, troop along 
the sidewalks, and encroach upon lawns to the very door-stone of 
rich and poor alike. 
The common dandelion (Taraxacum officinale Weber) is gen¬ 
erally recognized in our state as about the worst weed pest in 
lawns. A native of Europe, this plant was early introduced into 
North America, where it has overrun nearly all parts of the coun¬ 
try except those of an arid or semi-arid character, and into these 
it has found its way wherever the land is brought under irrigation. 
Within our own range the dandelion seems to have found the con¬ 
ditions peculiarly favorable and entirely to its liking. Here we 
find it thriving, not only in lawns and gardens, but it is encroaching 
more and more upon the alfalfa fields of the irrigated plains and 
the meadows and pastures of our mountain parks.* 
The moisture requirements of this plant determine in large 
measure its local distribution, and for this reason it seems unable 
to gain or maintain a root-hold upon the native prairie without 
irrigation. This same factor of soil moisture has been found to 
determine in some measure the distribution of the weed in lawns, 
the best watered portions being especially favorable for its growth. 
When once well established, however, the larger dandelion plants 
can often endure a temporary period of drought severe enough to 
kill out the lawn grass. 
In its light relations, the common dandelion shows a wide 
range of adaptability. It is found growing vigorously in full sun¬ 
light as well as in the diffused light within the shadow of trees 
and buildings. 
In its altitudinal range, the common dandelion may reach an 
elevation of 11.000 feet, where it can be found associating with one 
or more subalpine and alpine native species of less economic im- 
* The red-seeded dandelion (Taraxacum erythrospermum) has been re- 
centlv found by the writer in a lawn at Fort Collins. This plant closely 
resembles the common dandelion except that it is usually smaller. The leaves 
are more deely cut-lobed. the flower heads are fewer in number and smaller 
and the seeds are brigTit reddish brown instead of dull greenish brown in 
color. , 
