242 PRACTICAL LESSONS IN SCIENCE. 



opposite-leaved aromatic plants, with an irregular corolla and 

 didynamous stamens, and a deeply four-parted ovary. It in- 

 cludes lavender, hyssop, peppermint, sage, catnip and other 

 interesting plants, but none of great economic value. 



The Oleacese or Olive Family is composed of trees and shrubs, 

 with simple or pinnate leaves, regular flowers, two stamens, and 

 two-celled ovaries. It includes the olive, which yields fruit, oil 

 and lumber, the different varieties of ash, which yield good tim- 

 ber, and some ornamental shrubs, as the lilac, jessamine and 

 others. 



The Asclepiadacese or Milkweed Family. The members of this 

 family are woody or herbaceous plants with an abundant milky 

 juice. The flowers are regular, calyx and corolla five parted; 

 the two distinct ovaries have a common stigma; the five sta- 

 mens monadelphous, the anthers closely surrounding the stigma 

 and partly adhering to it. The pollen is in waxy masses which 

 are distributed by insects. The structure of the flower is peculiar 

 and difficult to describe, but exceedingly interesting to study, the 

 structure no doubt having reference to cross fertilization by the 

 aid of insects. The flowers are arranged in umbels; the fruit con- 

 sists of a pair of pods containing many flat seeds, which are fur- 

 nished with a tuft of soft, silky hairs, called a coma, at one end. 

 The milky juice contains caoutchouc, and some plants are culti- 

 vated for ornament, but the plants are chiefly interesting for the 

 peculiar structure of their flowers. 



The Gourd Family is made up of tendril bearing herbs, with 

 watery juice, alternate palmately ribbed and lobed leaves, and 

 monopetalous flowers. It includes the gourd, pumpkin, squash, 

 watermelon, muskmelon and the cucumber. 



The Composite or Sunflower Family. This immense family 

 including as many as 10,000 species has representatives in all 

 parts of the world. Many of the species are of great beauty and 

 are much admired as ornaments, but few are of any economic 

 value. The small monopetalous flowers with their syngenesious 

 anthers are gathered into compact heads or masses which often 

 resemble single flowers. The tube of the calyx is coherent with 



