SUPPLEMENT. 



THE FAMILIES OF FLOWERING PLANTS. 



By CharIvES Louis Pollard. 

 CHAPTER XXYl.— Orders Opwitiales and Myrtiflorae. 



THE first-named order, which takes its name from the genus of cacti 

 to which the prickly pear belongs, consists only of the following : 

 Family Cactaceae. Cactus Family. This very widely known 

 group, perhaps the most distinctive of any of the plant families, com- 

 prises about 20 genera and 900 species, all of which are natives of the 

 western hemisphere ; many of them have, however, been naturalized in 

 the Old World. Their chief characteristic is the extremely succulent 

 tissue of which the plants are composed, making it possible for them to 

 thrive in very arid regions. In fact, cacti are never to be found either 

 in moist situations or in a humid climate. 



In habit the plants also exhibit wide variation. A few have leafy 

 stems, similar to those of most plants; but the great majority have 

 swollen, spherical, jointed or angular stems, with practically no leaves 

 whatever, the latter being represented by minute spines and their place 

 being taken by clusters of sharp spines. The flowers are usually regu- 

 lar, with a calyx of numerous combined sepals, and a corolla of numer- 

 ous petals. The stamens, which have very long filaments, are also in- 

 numerable. The ovary is one-celled with a single style and several 

 stigmas. The fruit is fleshy and frequently edible, with a pleasant sub- 

 acid flavor. 



On account of the ease with which they may be cultivated, the 

 oddity of their shapes and the beauty of their flowers, the Cactaceae 

 have always been popular as house plants. The genus Cereus stands 

 pre-eminent in the number of species and variety of flowers. Everyone 

 is familiar with Cereus grandiflorus, the "night-blooming" Cereus, and 

 those who have traveled through the desert regions of Arizona and New 

 Mexico have observed the tall columnar stems of the giant cactus (C. 

 giganteus) indigenous throughout that region. Scarcely less interesting 

 are the various forms of prickly-pears (species of Opiuitia), which serve 

 a number of useful purposes in the countries where they grow. The 

 tuna (0. Tuna) is used as a hedge, and the young juicy joints of this, 

 after the spines have been & ;-'ged oft', are eaten by cattle. 0. Ficus- 



