Fig. 91.—Speedwell. (× ½.)
Calceolaria, musk, gloxinia, and snapdragon—other members of the family—are often cultivated in gardens.
The flowers of the musk are especially interesting, because they show so well what is called irritability,—the power which all living things possess of acting in a definite manner in response to a definite irritation or stimulus. We have already seen good examples of plant-irritability in the way a climbing stem winds itself round a support. The stigma of the musk flower has two flaps. If these are touched with a hair or bristle they quickly close together, but presently open again as if they had found out that they had been tricked. When, however, a little pollen is put on the flaps they close finally, for their whole object is accomplished.
Some of the plants in this family are poisonous, the foxglove being especially so in all its parts.
24. THE LABIATES.
1. The deadnettle.—Examine a deadnettle plant ([Fig. 92]). Notice the habit of growth, and write down a description of the shape and appearance of the stem and leaves. What is the shape of the flower? How many sepals, petals, and stamens has it? Do the stamens ripen first, or does the pistil? What insects do you find visiting the flower? Try to find out how they pollinate the stigma.
