Minnesota Plant Life. 



377 



grouped the pennyroyals, the basils, the hyssops, the mountain- 

 mints, water-hoarhounds and peppermints, in all of which the 

 flowers are clustered in small dense whorls in the axils of the 

 leaves. Sometimes, when many of these whorls arise close to- 

 gether, near the end of the stem, they become confluent into a 

 spike. 



Horsemints and dragon's-heads. Of the various mints several 

 are decidedly handsome plants. The horsemint, for example, 

 with its heads of two-lipped flowers, is an abundant and beau- 

 tiful herb of the woods. There are two sorts in Minnesota, 

 one with a yellowish flower and the other with pinkish or 

 purplish heads. The dragon's- 

 heads, with their light blue 

 flowers in close clusters and 

 the false dragon's-heads with 

 rose-colored flowers are inter- 

 esting plants of the northern 

 and central portions of the 

 state. The water-mints, found 

 in great abundance in springs 

 and along the edges of brooks, 

 present a variety of forms, 

 many of which, except by mi- 

 nute characters, are difficult to 

 distinguish from each other. 



Some mint flowers are very 

 interesting mechanisms for the 

 utilization of insects in the 

 work of pollination. In the 



sages, for example, the two stamens are hung on levers and 

 rest under the arched upper lip of the flower. When a bee 

 visits the flower it stands upon the lower lip and thrusts its bill 

 down towards the base of the flower, as it does so, striking with 

 its head the short arms of the levers. The two long arms 

 bearing the pollen pouches are thus brought down on the back 

 of the insect like hammers, leaving there a couple of patches 

 of pollen spores, several hundred spores in each patch. After 

 this mechanism of the flower has been set in motion by the 

 visit of a bee, the slender stigma-stalk of the pistil drops down 



FIG. 180. 



Horse-mint. After Britton and 

 Brown. 



