442 



DICOTYLEDONES. 



In each of the 2 loculi of the ovary are 2 ovules. Embryo curved, 

 with thin, folded cotyledons. Endosperm absent. The inflorescences 

 are racemes with a more or less elongated main axis and terminal flower (which 

 sometimes has 10 stamens); when the lateral branches are developed they are 

 similar to the main axis. In some species both corolla and petal- stamens are 

 suppressed. Acer is pollinated by insects, Negundo by the wind. 88 species ; 

 North Temperate zone. Acer in the Tertiary from the Oligocene. The follow- 

 ing are native plants: Maple (Acer campestre), Sycamore (A. pseudoplatanus, 

 doubtful native). Important as avenue trees and timber. Sugar is obtained 

 from the spring sap of the Sugar Maple (N. Am.). 



Order 5. Malpighiaceae. A tropical (especially American) order closely 

 related to the Aceracese, having often the same form of fruit (but 3-partite). 

 Some species are lianes with anomalous stem-structure. Leaves opposite. The 

 flowers are regular or obliquely zygomorphio (the plane of symmetry passing 

 through sepal 3, with S5, P5, A5 + 5, G3; 1 pendulous ovule in each loculus. 

 Important characteristics for identification are the numerous grandular struc- 

 tures on the sepals. Peculiar 2-spined hairs are found in some. Malpighia, 

 Bunchosia, Galphimia, Tetrapteris, Heteropteris, etc. About 600 species. 



Order 6. Erythroxylacese. Sepals 5, petals 5 (with a ligular corona), 10 

 stamens in one bundle. Gynoeceum 3-locular. Fruit a drupe. Tropical 

 (especially American) trees and shrubs, the Coca-plant (Erythroxylon coca) 

 being best known. Its leaves are considered by the inhabitants of Chili and 

 ^Peru to be one of the indispensable necessaries of life ; they are chewed, and 

 possess intoxicating, exhilarating properties, and contain the alkaloid cocaine, 

 which is frequently employed as a local anaesthetic. 103 species ; chiefly in 

 America. 



Order 7. Vochysiaceas. Trees ; Trop. Am. 1 stamen. 140 species. 



Order 8. Trigoniaceae. Shrubs; Trop. Am. 30 species. 



Order 9. Tremandraceae. Polygalacese with regular flowers. 27 species. 

 Australia. 



Order 10. Polygalacese. Herbs or shrubs (some tropical 

 species are lianes) with scattered (rarely opposite), simple and 

 most frequently quite entire leaves, without stipules. The flowers 

 are usually borne in terminal spikes or 

 racemes, and are strongly zygomorphic 

 (the plane of symmetry being median) ; 

 they have 5 free sepals, the 2 lateral 

 ones of which (4 and 5 in Figs. 475, 476) 

 are very large, petaloid, and frequently 

 project on each side like the "wings" 

 of a Pea- flower ; petals 5, of which the 

 two lateral ones are wanting or rudi- 

 FIG. ,475. Diagram of Poly- mentary (dotted on Fig. 475), and the 



gala: d a gland in the posterior anterior " the farf " ( Fif? . tfQ c ) ig la 

 side of the flower ; a and /3 the 



two caducous bracteoies. hollow and boat-shaped, and frequently 



