406 GENERAL BOTANY 



Close-pollination and cross-pollination are effected by insects, 

 which visit the flowers for the nectar secreted by a ringlike 

 nectary* at the base of the stamens. 



The fruit is an aggregate of small stone fruits, or drupes, in 

 both the raspberry and the blackberry, the separate drupes arising 

 from the ovary wall, which forms* in ripening, an outer fleshy 

 wall and an inner stony part inclosing the seed. In the black- 

 berry (Fig. 256, c) these stone fruits are aggregated on a fleshy 

 receptacle which, as in the strawberry, forms a part of the ripened 

 aggregate fruit. In the raspberry the separate stone fruits unite 

 by interlocking hairs, but separate easily from the receptacle, 

 which does not in this instance enter into the edible portion of 

 the fruit, as in the blackberry and the strawberry. 



ROSA (ROSES) 



Habit. The roses proper are woody perennials, often becoming 

 shrubby in habit, with compound leaves and conspicuous flowers 

 borne singly or in clusters. The plants are principally noted for 

 their ornamental effects, due to the great size and beauty of the 

 flowers under cultivation. 



Flowers and fruit. The flowers of the wild and cultivated 

 roses are perigynous, with an urn-shaped receptacle which bears 

 the conspicuous petals, calyx tubes, and stamens on the rim 

 of the cup (Fig. 256, e). The pistils are numerous, springing 

 from the base of the receptacle and inclosed by it. 



Pollination. The stigmas protrude beyond the urn-shaped re- 

 ceptacle in the open flower, and the stamens bend outward, facil- 

 itating cross-pollination, although self-pollination is not precluded. 

 In the development of the fruit, or rose hip (Fig. 256, /), both 

 the pistils and the receptacle have a part. The pistils develop 

 into hard, bony, achenelike fruits inclosed by the receptacle, 

 which becomes fleshy and bright red or scarlet at maturity. The 

 stamens and corolla disappear during fruit formation, but the 

 calyx lobes adorn the upper border of the rose hip after it is ripe. 

 The seeds are scattered when the fruit decays, or they may be 

 disseminated by animals if the fruit is eaten. 



