[Chap. LI SOME FAMILIES OF FLOWERING PLANTS 699 



absciss layer occurs at the base of the petiole, the trunk of the tree 

 is quite smooth. If it occurs at some distance from the base of the petiole, 

 the leaf bases remaining give to the trunk a rough, shaggy appearance. 



The lily family (Liliaceae). The yuccas and aloes of the desert; the 

 edible onions, garlic, and asparagus; and the well-known ornamental 

 tulips, hyacinths, lilies, and trilliums are members of the lily family. 

 All except a few are perennial or biennial herbs. One of the chief char- 

 acteristics of the plants is the presence of an underground bulb or 

 corm, or sometimes a fleshy rootstock. 



The lilies are widely distributed naturally, and many species are cul- 

 tivated in enormous numbers. Few families of plants have more at- 

 tractive flowers. The flowers may be single or variouslv grouped into 

 racemes, panicles (Fig. 337), or umbels. Thev usuallv have three petal- 

 like sepals, three petals, six stamens, and a single three-carpellate pistil. 

 The fruit is a capsule" containing few to many seeds. Some 200 genera 

 and 2500 species have been described. 



Closely related to the lilies is the amaryllis family {Amari/llidaceae), 

 which includes amaryllis, narcissus, and agave. 



The pineapple family (Bromeliaceae) . The plants of the pineapple 

 family are largely epiphytes or air plants and are confined to the tropics 

 and subtropics. The pineapple and a few others grow on soil ( Fig. 163 ) . 

 The "Spanish moss" is a rootless plant which forms festoon-like masses 

 on all sorts of plants, such as oaks, pines, palms, and orange trees. This 

 plant and others, more like the pineapple in appearance, may grow not 

 only as epiphytes, but on wires and fences as well. There are about 

 40 genera and 1000 species. 



The commercial "pineapple" is a flesh v multiple fruit. The terminal 

 floral axis above the flowers develops into a leafv stem, and this is used 

 as a cutting in propagating pineapples. The floral parts, bracts and axis 

 together constitute the "pineapple." 



The banana family {Musaceae). This familv includes large-leaved 

 herbs 15 to 20 feet high. The sheathing leaf petioles overlap, forming 

 a cylinder of concentric layers that looks like a stem. The real stem is 

 a tuberous rhizome from which the flower stalks develop and extend 

 upward through the hollow cylinder fonned by the sheathing petioles. 

 The erect shoot bears one bunch of bananas and dies. New plants de- 

 velop from suckers. The banana of commerce never contains fully 



- Asparagus, lily-of-the-\alley, and false Solomon's seal are often placed in a separate 

 family (Convallariaceae); in such plants the fruit is a many-seeded berry. 



