SUPPLEMENT. 
THE FAMILIES OF FLOWERING PLANTS. 
By CHARLES LouIs POLLARD. 
CHAPTER XXVI.—Orders Opuntiales and Myrtiflorae. 
HE first-named order, which takes its name from the genus of cacti 
T 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 (C7 
giganteus) indigenous throughout that region. Scarcely less interesting 
are the various forms of prickly-pears (species of Opuntia), which serve 
a number of useful purposes in the countries where they grow. The 
tuna (0. Tuna) is used as a bedge, and the young juicy joints of this, 
after the spines have been «</-ged off, are eaten by cattle. O. Ficus- 
