. Elementary botany. Botany. 37° ECOLOGY. up as they are whirled along, often miles away. In late spring or early summer the pods of the willow burst open, exposing the seeds, each with a tuft of white hairs making a mass of soft down. As the delicate hairs dry,. Fig. 472. Touch-me-not (Impatiens fulva); side and front view of flower below; above unopened pod, and opening to scatter the seed. they straighten out in a loose spreading tuft, which frees the individual seeds from the compact mass. Here they are caught by currents of air and float off singly or in small clouds. 676. The prickly let
. Elementary botany. Botany. 37° ECOLOGY. up as they are whirled along, often miles away. In late spring or early summer the pods of the willow burst open, exposing the seeds, each with a tuft of white hairs making a mass of soft down. As the delicate hairs dry,. Fig. 472. Touch-me-not (Impatiens fulva); side and front view of flower below; above unopened pod, and opening to scatter the seed. they straighten out in a loose spreading tuft, which frees the individual seeds from the compact mass. Here they are caught by currents of air and float off singly or in small clouds. 676. The prickly lettuce.—In late summer or early autumn the seeds of the prickly lettuce (Lactuca scariola) are caught up from the roadsides by the winds, and carried to fields where they are unbidden as well as unwel- come guests. This plant is shown in fig. 473. 677. The wild lettuce.—A related species, the wild lettuce (Lactuca cana- densis) occurs on roadsidrs and in the borders of fields, and is about one meter in height. The heads of small yellow or purple flowers are arranged in a loose or branching panicle. The flowers are rather inconspicuous, the rays projecting but little above the apex of the enveloping involucral bracts, which closely press together, forming a flower-head more or less flask- shaped. At the time of flowering the involucral bracts spread somewhat at the apex, and the tips of the flowers are a little more prominent. As the flowers then wither, the bracts press closely together again and the head is closed. As the seeds ripen the bracts die, and in drying bend outward and down- ward, hugging the flower stem below, or they fall away. The seeds are. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Atkinson, George Francis, 1854-1918. New York, H. Holt
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