[Chap. LI SOME FAMILIES OF FLOWERING PLANTS 



715 



Fig. 352. Flower clusters of button-bush (Cephalanthiis occidcntalis) . 



mints make them unusually well-recognized plants (Fig. 353). Some 

 200 genera and 3000 species are known. Mints are distributed very gen- 

 erally throughout the world. Common representatives are catnip, hoar- 

 hound, peppermint, thyme, sage, lavender, coleus. The stems of the 

 herbaceous species are commonly square in cross section, and many of 

 the flowers are irregular and "two-lipped." The mints are commercially 

 valuable for their volatile oils used in flavoring extracts, perfumes, and 

 medicine. 



The potato family (Solanaceae). This family is generally distributed, 

 but especially abundant in the tropics and subtropics. It consists of 

 about 80 genera and 2000 species. They are usually herbs, but shrubby 

 and even tree-like species grow in the tropics. The presence of under- 

 ground tubers, as in the potato, is unusual in plants of the family. 



Some plants are deadly poisonous (nightshade), troublesome weeds 

 (jimson weed), attractive ornamentals (petunia, jessamine, matrimony 

 vine), or sources of food (potato, tomato, eggplant, peppers), of to- 

 bacco, and of powerful drugs, such as atropin and belladonna secured 

 from the deadly nightshade. The potato in many countries ranks second 

 only to wheat as an agricultural source of food (Fig. 354). 



