FAMILIES OF FLOWERING PLANTS 217 
trees, natives of the southern states, and known as “silver bell” trees 
from the campanulate, snowy-white corolla. WV. dipterum has a 2-winged, 
and MV. tetrapterum a 4-winged, fruit. (Fig. 187.) There are also sev- 
eral native species of Styrax, which are also handsome shrubs; the 
flowers are usually very pubescent in this genus. 
Storax is a balsamic resin derived from S. officinale, a native of the 
Levant. It is obtained by submitting the bark to heavy pressure, and 
was formerly extensively used by perfumers and also in medicine. Of 
late it has been supplanted by the product of the Asiatic sweet gum, 
Liquidambar orientalis. Styrax Benzoin yields the benzoin of commerce, 
which is still employed in the manufacture of perfumes and in medicine 
for pulmonary troubles. 
CHAPTER XXX.—Ovrder Gentianales. 
This group contains the seven families: Oleaceae, Salvadoraceae, 
Loganiaceae, Gentianaceae, Menyanthaceae, Apocynaceae and. Asclepiada- 
ceae. The plants comprised in it may usually be distinguished by their 
opposite leaves, regular flowers with nerved corollas, stamens as many 
as the corolla-lobes and alternate with them (or fewer), and ‘by the two 
distinct ovaries or 2-celled single ovary. The order as a whole is me- 
dicinal; it contains some useful, and not a few ornamental, plants. 
Family Oleaceae. Olive Family. About 21 genera and 500 species, 
widely distributed. They are trees or shrubs with simple or pinnate 
leaves and 2-4-parted flowers, having the ovary superior and free from 
the calyx. In one genus (Adelia) and in many species of another (Frax- 
inus) the corolla is wanting. The fruit may be either a capsule, a samara 
(Key-fruit, like that of the maple) a berry or a drupe. 
Olea Europea, the olive, is widely cultivated throughout Southern 
Europe, and is of considerable economic importance. It also thrives in 
Southern California. The fruit is a true drupe, consisting of a hard 
stone or endocarp,’surrounded by a fleshy exocarp. The familiar lilac 
belongs to the genus Syringa, which affords another example of faulty 
popular nomenclature. The plant to which the name syringa is uni- 
versally applied, namely, the mock orange (Philadelphus) belongs to an 
entirely dfferent family, and neither resembles, nor is in any way re- 
lated to the lilac. Frawxinus, the ash, contains numerous species in 
Europe and America, most of which are handsome trees, with clean 
foliage, and very popular for park planting. One of the most beautiful 
of our native shrubs, the fringe-tree (Chionanthus) also belongs to this 
family. (Fig. 188.) 
