FAMILIES OF FLOWEEING PLANTS 217 



trees, natives of the southern states, and known as " silver bell " trees 

 from the campanulate, snowy-white corolla. M. dipterum has a 2-winged, 

 and 31. 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 supjilanted by the product of the Asiatic sweet gum, 

 Liquidambar orientcdis. Styrax Benzoin yields the benzoin of commerce, 

 which is still employed in the manufacture of perfumes and in medicine 

 for pulmonary troubles. 



Chapter XXX. — Order Ge7itia7iales . 



This group contains the seven families : Oleaceae, Salvadoraceae, 

 Logaiiiaceae, Gentianaceae, 3IenyantJiaceae, Apocyiuiceae 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^-parted flowers, having the ovary superior and free from 

 the calyx. In one genus (Adelia) and in many species of another {Frax- 

 iniis) 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 Syrhuja, 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. Fraxinus, 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.) 



