CHARACTERISTICS OF BOTANICAL FAMILIES 



open on the upper side. Through this split the pistil pro- 

 jects, later the pod or legume. The calyx is unequal! . 

 divided. To this Family belong not only the pea and bean, 

 but cassia, liquorice, logwood, and other useful plants. N< >ne 

 is poisonous. Many are ornamental climbers, with showy 

 blossoms and graceful foliage. Their leaves are often com- 

 pound, and the leaflets may be sensitive, folding when 

 touched, also many of them "sleep" at night. The Pea 

 Family contains herbs, shrubs, and trees. 



The Spurge Family contains the castor-oil and croton- 

 oil plants ; manihot, from which tapioca is made ; and rubber- 

 trees, the latter having come into great prominence in these 

 days of automobiles and rubber tires. The stamens and 

 pistils occur in different flowers, sometimes on the same 

 plant, sometimes on different ones. Such flowers are called 

 monoecious or dioecious. It is a very large Family in the 

 tropics, but with us is known mostly in the genus Euphorbia. 

 The manner of the flowering of this genus is singular. There 

 is no proper calyx or corolla, but the flowers are surrounded 

 by an involucre resembling a calyx divided into 4 or 5 lobes 

 which are colored and cup-shaped. Between the lobes are 

 thick glands. Within the involucre (once considered the 

 true flower) numerous staminate flowers are borne, each 

 consisting of a single stamen jointed on a tiny stalk (pedicel), 

 very like a filament. A small bract accompanies each 

 stamen. From the center of the cluster of stamens a single 

 pistil is raised on a long stalk, the pistil consisting of a 

 3-celled ovary, 3 styles, and 6 stigmas. The plants contain 

 a milky juice. 



Parsley Family. — The flowers of plants belonging to this 

 Family grow in umbels, which are frequently compound, 

 forming umbellets. They possess oil-tubes — minute canals 

 running lengthwise of the fruit — containing aromatic oil, 

 which can only be seen with a strong microscope. 



The style and its stigma develop in advance of the stamens, 

 thus preventing self-pollination. Insects carry the pollen 

 of one flower to the stigma of another, both of which happen 

 to be ripe at the same time. 



The stems are generally hollow. 



The plants vary in size and color, but nearly all have the 

 umbel form of blossom and the compound leaves. The 



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