ANGIOSPERMJS 



385 



surrounding the sporophylls. The inner palea belongs to the floral axis, while 

 the outer one (" flowering glume ") belongs to the axis of the spikelet. Above 

 the outer palea there are usually present two small bodies (Lodicules), which, by 

 their enlargement, force open the paleae. These are sometimes considered to be 

 rudimentary perianth leaves, but there is much doubt about this. 



In the Sedges (Fig. 360) 

 the flowers are more commonly 

 diclinous than in the Grasses, 

 but structurally are similar to 

 them. 



The fruit is indehiscent, a 

 nutlet or caryopsis, and the 

 abundant starchy endosperm 

 of many Grasses makes these 

 the most important of all food 

 plants. The grain (caryopsis) 

 of the Grasses consists of the 

 ovary, which is closely adhe- 

 rent to contained seed. The 

 embryo in the ripe grain is 

 well-developed in the Grasses, 

 and the cotyledon (Scutellum) 

 acts as an absorbent organ for 

 the laterally placed embryo. 

 In the Sedges the embiyo is at 

 the apex of the endosperm 

 (Fig. 360, G), and much less 

 developed than it is in the 

 Grasses. 



The Grasses and Sedges are 

 widespread, especially impor- 

 tant in the cooler parts of the 

 world. The Sedges are largely 

 water-plants, but the Grasses 

 often grow in dry exposed 

 regions, where they are the 

 most important plants, as upon 

 our own western prairies. All 

 the members of the group have 

 jointed stems and long sheath- FlG> 359. Zea Mays. Pistillate flowers, 

 ing leaves, two-ranked, with (After BAILEY.) 



split sheaths, in the Grasses ; 



three-ranked, with entire sheath, in the Sedges. The stems are usually hollow 

 in the Grasses, and solid in the Sedges. The giants of the order are the Bam- 

 boos, some of which are 30 to 40 metres in height. The outer tissues of all of 

 them are heavily impregnated with silica. 



Economically the Sedges are of small importance. Perhaps the most note- 

 worthy of these is the Papyrus ( Cyperus papyrus) . The Grasses, on the other 

 hand, are the most important of all plants. In temperate climates they form the 

 staple food of herbivorous animals, and all the cereals Wheat, Rice, Corn, etc. 

 are Grasses. The Bamboos and Sugar-cane are also Grasses. Of our native 

 Grasses, the Wild-rice (Zizania aquaticd) is the most important as a source 

 of food. 



2c 



