MONOCOTYLEDONS AND DICOTYLEDONS 241 



bamboos, and pasture grasses, all of them immensely use- 

 ful plants. 



The flowers are very simple, having no evident perianth 

 (Fig. 222). Most commonly a flower consists of three sta- 

 mens, surrounding a single carpel, whose ovary ripens into 

 the grain, the characteristic seed-like fruit of the group. 

 The stamens, however, may be of any number from one to 

 six. The flowers, therefore, are naked, with indefinite num- 

 bers, and hypogynous, indicating a comparatively simple 

 type. It is also noteworthy that the group is anemophilous. 



One of the notcAVorthy features of the group is the 

 prominent development of peculiar leaves {bracts) in con- 

 nection with the flowers. Each flower is completely pro- 

 tected or even inclosed by one of these bracts, and as the. 

 bracts usually overlap one another the flowers are invisible 

 until the bracts spread apart and permit the long dangling 

 stamens to show themselves. These bracts form the so- 

 called "chaff" of wheat and other cereals, where they 

 persist and more or less envelop the grain (rij^ened ovary). 

 As they are usually called glumes, the grasses and sedges 

 are said to be ghimaceous plants. 



Grasses are not always lowly plants, for in the tropics 

 the bamboos and canes form growths that may well be 

 called forests. The grasses constitute the family GraminecB^ 

 and the sedges the family Cyperacem. 



133. Palms. — More than one thousand species of palms 

 are grouped in the family Palmacece. These are the tree 

 Monocotyledons, and are very characteristic of the tropics, 

 only the palmetto getting as far north as our Gulf States. 

 The habit of body is like that of tree-ferns and Cycads, a 

 tall unbranched columnar trunk bearing at its summit a 

 croAvn of huge leaves which are pinnate or palmate in char- 

 acter, and often splitting so as to appear lobed or compound 

 (Figs. 223, 224). 



The flower clusters are usually very large (Fig. 223), 

 and each cluster at first is inclosed in a huge bract, which 



