FAMILIES OF FLOWEEING PLANTS 



95 



give a good idea of the floral structure in tliis family, and of the curved 

 embryo shown in the cross-section of the fruit. 



With the exception of Chenopodium, the species of which are mostly 

 distributed over the country as weeds, the American Chenopodiaceae 

 are largely natives of the western States, where they form the predom- 

 inant vegetation of the so-called " alkali " plains, and are known as 

 saltbushes {Atriplex and Snaeda). Farther south one meets the shrubs 

 known as " greasewoods " {Sarcobatus), which are abundant in the des- 

 ert regions of the lower Colorado watershed. When growing in saline 

 soils, either in the interior, or along the coast, the plants are usually 

 extremely fleshy and succulent, like other halophytes. (See Fig. 78.) 



As potherbs many of the mem- 

 bers of this family are highly es- 

 teemed. The leaves of spinach (Spi- 

 nacia), of the beet (Beta), and of the 

 common lamb's quarters {Chenopo- 

 dium album) are used for this pur- 

 pose. The beet, moreover, is of com- 

 mercial importance, aside from its 

 value as a vegetable, on account of 

 the sugar extracted from it. The 

 sugar-beet industry, particularly in 

 France, has assumed large propor- 

 tions in recent years, and the product 

 is in many respects superior to cane 

 sugar. Soda and potash are obtain- 

 ed from some species of Scdsola, while 

 many of the genera yield essential 

 oils valuable in medicine as antispas- 

 modics. 



Family Amaranthaceae. Ama- 

 ranth family. Contains about 40 

 genera and 450 species, widely distributed, but most abundant in the 

 tropics. They are herbs or undershrubs, with simple leaves and small 

 perfect monoecious or dioecious flowers, usually borne in dense clus- 

 ters. The perianth may be in one or two series, but there are no true 

 petals. Like other families in the order Centrospermae, the Amaranth 

 fruit is utricular, but it splits in a transverse ring at about the middle ; 

 this is called by botanists a circumscissile dehiscence. The flower and 

 fruit are shown in the middle line of Fig. 77. 



The genus Amarantlms, which shares Avith Chenopodium the name 

 of "pig- weed," is one of the largest representatives of the family, and 

 includes a number of familiar weeds of the eastern United States. The 



Fig. 78. The common saltwort {Salicornia 

 herbacea), showing the fleshy cylindrical 

 leaf. After Britton & Brown, 111. Fl. North- 

 east. U. S. 



