462 DICOTYLEDONES. 



B. FRUIT GLABROUS (i.e. without hairs) : Primus (Plum) has a 

 glabrous fruit with bluish bloom ; the stone is .compressed, smooth 

 or wrinkled. The flowers are borne solitarily or in couples, and 

 open before or at the same time as the leaves ; they are borne on 

 shoots without foliage-leaves. Cerasus (Cherry) has a glabrous, 

 spherical fruit, without bloom, and a spherical stone. The flowers 

 are situated in 2-many-flowered umbels or racemes, and open at the 

 same time as the leaves or a little before them. Long-stalked flowers 

 in umbels are found in C. avium (Wild Cherry), C. vuluaris (the cultivated 

 Cherry, from Western Asia) ; racemes at the apex of leaf-bearing branches and 

 small spherical fruits are found in C. padus (Bird Cherry), C. virginiana, C. 

 laurocerasus (Cherry-laurel), C. mahaleb. 



POLLINATION. Primus splnosa (Sloe, Blackthorn) is protogyuous, but the 

 stamens are developed before the stigma withers. Honey is secreted by the 

 receptacle. Cerasus padus (Bird-Cherry) agrees in some measure with P. apinosu. 

 In the flowers of the Plum and Cherry the stamens and stigma are developed 

 simultaneously and self-pollination seems general ; the stigma, however, overtops 

 the inner stamens and thus promotes cross-pollination. DISTRIBUTION. 114 

 species in the N. Temp, zone ; few in the warmer regions ; the majority from 

 W. Asia. C. vulgaris, from the regions of the Caspian ; Primus spinosa, 

 insititia (Bullace), domeslica (Plum, from the Caucasus, Persia). USES, princi- 

 pally as fruit-trees : Cherry, Plum, Apricot, etc. ; " Almonds " are the seeds of 

 Amyrjdalus communis (W. Mediterranean), " bitter," " sweet," and " shell " 

 almonds are from different varieties, the latter being remarkable for the thin, 

 brittle stone. In the majority of species and in almost all parts of the plant 

 (especially the bark, seed and leaves) is found the glycoside, amygdalin, which 

 forms prussic acid. Many form gum, and the seeds have fatty oils ("Almond 

 oil"). OFFICINAL: the seeds and oil of Ami/gdalus commnnis, and the fruit of 

 the Cherry ; in other countries also the leaves of C. laurocerasus. The stems 

 of Cerasus mahaleb are used for pipes. Ornamental Shrubs : Amygdalus nana, 

 Cerasus laurocerasus. 



Order 3. Chrysobalanaceae. Tropical Amygdalaceae with zygomorphic 

 flower and gynobasic style. 200 species; especially Am. and Asia. Chrysoba- 

 lanus icaco (Cocoa-plum) is cultivated on account of its fruit (Am.) 



Order 4. Pomaceae. Trees and shrubs, most frequently with 

 simple leaves and caducous stipules. The flowers (Fig. 505) have 

 5 sepals, 5 petals and generally 20 stamens (10 + 5 + 5', or 10 + 10 + 5). 

 There are from 1-5 carpels, which unite entirely or to some extent 

 with each other, and with the hollow, fleshy receptacle (the flower 

 becoming epigynous), (Figs. 505, 506, 507). The carpels are nearly 

 always free on the ventral sutures, rarely free at the sides also. 

 The wfrole outer portion of the fruit becomes fleshy, but the por- 

 tions of the pericarp surrounding the loculi (endocarp) are most 

 frequently formed of sclerenchymatous cells, and are more or less 



