Some Families of Angiosperms 



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Grass stems are usually round, and the internodes are hollow. 

 The leaves are arranged alternately in two ranks. 



Fig. 330. Panicle and flower of bent grass (Agrosiis), the latter showing two glumes 

 and the much shorter lemma adjoining the pistil and stamens. 



Closely related to the grasses are the sedges {Cyperacece), with 

 triangular, solid, unjointed stems, and leaves in three ranks. The 

 sedges are common in swamps, marshes, and low grounds. The 

 papyrus, a sedge of the Nile Valley, was one of the first plants 

 used in paper making. In fact, our word " paper " comes from 

 the name of this sedge. 



The aroids {Araceae). The calla lily, jack-in-the-pulpit, 

 skunk cabbage, and caladiums are examples of a large family of 

 tropical and temperate herbs, embracing not less than 1000 species. 

 The flower cluster consists of a spike (spadix) of very simple 

 flowers, inclosed by a large, sometimes highly colored bract (spat he) . 

 Many of these flowers are noted for their disagreeable odors. 



The rootstocks of some species of caladium, colocasia, and arum 

 accumulate starch and are a source of food in the tropics. 



