LEADING FAMILIES OF FLO WEEING PLANTS 347 



and lily of, the valley. Showy wild genera are the following : 

 many lilies, the dogtooth violet (Fig. 280), Trillium (Fig. 279), 

 Clintonia, and several Rocky Mountain and Pacific coast genera, 

 such as Brodicea and Calochortus. . 



Useful plants are not very numerous in the Lily family. 

 Asparagus and onions are common articles of food. Colchicum, 

 Veratrum, Aloe, Smilax, and a few other genera yield valua- 

 ble medicines. The so- 

 called New Zealand flax 

 produces an important 

 fiber. 



315. The Orchis fam- 

 ily (Orchidacea*). The 

 orchids number more 

 than 5000 species dis- stig 

 persed throughout trop- 

 ical, sub-tropical, and 

 temperate climates. Few 

 other plants seem as ca 

 pricious in their distri- 

 bution, since a single 

 individual or a small 

 patch of them may con- 

 stitute the only repre- 

 sentation of a species 

 throughout a considerable region. Orchids are all herbs, but 

 vary greatly in habit, from low forms with hardly any stem 

 aboveground, like the true Orchis and .the lady's-slipper 

 (Cypripedium) (Figs. 281 and 282), to tall climbers like the 

 vanilla plant and such air plants as Fig. 20. Some genera, 

 like the coralroot, are almost or quite destitute of chlorophyll, 

 and live as root parasites or as saprophytes. Many species 

 have tubers and are able to survive a long dry season. The 

 flowers are of . peculiar /forms and have developed the most 

 remarkable known structures for insect pollination. Great 

 numbers of orchids are cultivated in greenhouses, and are 



FIG. 282. Lengthwise section of one of the 

 flowers of Fig. 281 



stig, stigma; sta, imperfect stamen of bract- 

 like appearance ; a, anthers of perfect stamens ; 

 o, ovary 



