Page:Popular Science Monthly Volume 19.djvu/182

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170
THE POPULAR SCIENCE MONTHLY.

or crown, which botanists term a pappus. Of this the dandelion and John Go-to-bed-at-noon, so called from its habit of shutting its flowers about mid-day, are well-known examples. Tufts of hairs, which are themselves sometimes feathered, are developed in a great many Composites, though some, as, for instance, the daisy and lapsana, are without them: in some very interesting species, of which the common Thrincia hirta of our lawns and meadows is one, there are two kinds of fruits, as shown in Fig. 13, b, one with a pappus and one without. The former are adapted to seek "fresh woods and pastures new," while the latter stay and perpetuate the race at home.

A more or less similar pappus is found among various English plants—in the Epilobium (Fig. 13, a), Thrincia (Fig. 13, b), Tamarix

PSM V19 D182 Pappus of various plants.jpg
Fig. 13.a, willow herb {Epilobium); b, two forms of seed of Thrincia hirta; c, Tamarix; d, willow {Salix); e, cotton grass {Eriophorum); f, bulrush {Typha).

(Fig. 13, c), willow (Fig. 13, d), cotton-grass (Fig. 13, e), and bulrush (Fig. 13, f); while in exotic species there are many other cases—as, for instance, the beautiful oleander. As in the wings, so also in that of the pappus, it is by no means always the same part of the plant which develops into the crown of hairs. Thus in the Valerians and Com-