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.
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.
| 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. |
Various Forms of Corolla.—The corolla often assumes very definite or distinct forms, especially when gamopetalous. It may have a long tube with a wide-flaring limb, when it is said to be funnelform, as in morning-glory and pumpkin. If the tube is very narrow and the limb stands at right angles to it, the corolla is salverform, as in phlox. If the tube is very short and the limb wide-spreading and nearly circular in outline, the corolla is rotate or wheel-shaped, as in potato.
A gamopetalous corolla or gamosepalous calyx is often cleft in such way as to make two prominent parts. Such parts are said to be lipped or labiate. Each of the lips or lobes may be notched or toothed. In 5-membered flowers, the lower lip is usually 3-lobed and the upper one 2-lobed. Labiate flowers are characteristic of the mint family (Fig. [185]), and the family therefore is called the Labiatæ. (Literally, labiate means merely “lipped,” without specifying the number of lips or lobes; but it is commonly used to designate 2-lipped flowers.) Strongly 2-parted polypetalous flowers may be said to be labiate; but the term is oftenest used for gamopetalous corollas.
Fig. 186.—Personate Flower of Toadflax.
Labiate gamopetalous flowers that are closed in the throat (or entrance to the tube) are said to be grinning or personate (personate means masked). Snapdragon is a typical example; also toadflax or butter-and-eggs (Fig. [186]), and many related plants. Personate flowers usually have definite relations to insect pollination. Observe how an insect forces his head into the closed throat of the toadflax.