436 



BOTANY 



actinomorphic (Oxalis, Linum) or zygomorphic (Pelargonium, Tropceolum). 

 In the latter case the number of stamens is reduced. The carpels are usually 

 three to five, and may separate (Geranium) at maturity (Fig. 425, D). 



The Geraniaceae include several native species of Geranium, and the species 

 of Pelargonium are favorite garden plants. Oxalidacese, Linacese, and Tropceola- 

 cese also include familiar forms. Linum usitatissimum is the common Flax. 



To the Rutacese belong the various species of Citrus (Orange, Lemon, etc.), 

 and the Meliacese include the Umbrella-tree (Melia Azederach}, often planted 

 in the warmer parts of the United States. 



The Polygalaceae are represented by several species of Polygala, with strongly 

 zygoraorphic flowers. 



A 



FIG. 428. A, B, Acer saccharinum. D-F, A. dasycarpum. E, section of seed. 

 F, embryo removed from the seed. G, dSsculus glabra. H-J, Impatiens fulva. 

 J, flower with the parts displayed; s, sepals; p, petals; an, stamens; gy, carpels. 



The Euphorbiacese, which are doubtfully placed with the Geraniales, are plants 

 especially abundant in the warmer parts of the earth. The flowers (Fig. 426) 

 are diclinous and inconspicuous ; but they are often surrounded by a corolla-like 

 involucre which renders the inflorescence very conspicuous. This is seen 

 among our native species in E. corollata and E. marginata, but is still more 

 marked in such cultivated species as E. splendens and E. (Poinsettia) pul- 

 cherrima. Some of the South African Euphorbias are quite leafless and closely 

 resemble Cacti, from which they may be at once distinguished by their milky 

 juice. 



The Castor-bean (Ricinus) and the showy-leaved Crotons are common culti- 

 vated members of the Euphorbiacese. 



