Page:First course in biology (IA firstcourseinbio00bailrich).pdf/170

From Wikisource
Jump to navigation Jump to search
This page needs to be proofread.

gourd, pumpkin, the plant is monœcious ("in one house"). When they are on different plants, e.g. poplar, cottonwood, bois d'arc, willow (Fig. 182), the plant is diœcious ("in two houses"). Some varieties of strawberry, grape, and mulberry are partly diœcious. Is the rose either monœcious or diœcious?

Fig. 182.—Catkins of a Willow.

A staminate flower is shown at s, and a pistillate flower at p. The staminate and pistillate are on different plants.

Fig. 183.—Flower Of Garden Nasturtium.

Separate petal at a. The calyx is produced into a spur.

Fig. 184.—The Five Petals Of the Pansy, detached to show the form.

Fig. 185.—Flower Of Catnip.

Flowers in which the parts of each series are alike are said to be regular (as in Figs. 173, 174, 175). Those in which some parts are unlike other parts of the same series are irregular. Their regularity may be in calyx, as in nasturtium (Fig. 183); in corolla (Figs. 184, 185); in the stamens (compare nasturtium, catnip, Fig. 185, sage); in the pistils. Irregularity is most frequent in the corolla.