ACCESSORY STRUCTURES OF FRUITS. 



435 



it has the form of a three-lobed open scale, to the base of which the ribbed nut is 

 attached. Finally, in the Hop-hornbeam (Ostrya, fig. 437 6 ) it forms a loose papery 

 envelope. 



The Receptacle of the flower is not infrequently a conspicuous feature in con- 

 nection with the fruit. This is well shown in the Carolina Allspice, in Roses, and 

 in Pomacese. In the Carolina Allspice (Calycanthus, figs. 328 * and 328 2 ) an exca- 

 vated pitcher-like receptacle, invested on the outside with scales, incloses the achenes; 

 in the Rose there is a similar inclosure, here smooth and fleshy, and bearing a five- 

 leaved calyx above, this constitutes the hip. In the Apple, Pear, Quince, and other 

 Pomaceae, the receptacle forms an extremely succulent mass, in which the actual 



fruit is imbedded, and 

 with which it is entirely 

 fused (e.g. Quince, Cy- 

 donia, fig. 330 2 ). In 

 the Strawberry (Fra- 

 garia), on the other 

 hand, the fleshy recep- 

 tacle is convex, and 

 bears the little achenes 

 scattered over its sur- 

 face. Not always, how- 

 ever, is the receptacle 

 fleshy; thus, in the 

 Agrimony (Agrimonia 

 Eupatoria, figs. 328 s 

 and 328 4 ) it forms a dry and woody inclosure for the one or two achenes, and is 

 provided with numerous stiff hooked bristles on its periphery. 



Much less frequently does the flower-stalk (pedicel) take a share in the fruit 

 formation. This is so, however, in Anacardiacese, in some Rhamnacese, and in a few 

 other groups. Thus, for instance, in the tree which produces Cashew-nuts (Ana- 

 cardium occidentale, fig. 330 x ), the upper portion of the pedicel swells up into a 

 fleshy pear-like structure; on its summit is perched the kidney-shaped nut with its 

 inclosed seed. In Hovenia dulcis (allied to the Buckthorn) a similar arrangement 

 prevails, the flower-stalks are swollen, and contain a sweet red pulp appreciated by 

 the Chinese and Japanese. To these instances may be added the Fig (Ficus, cf. 

 figs. 240 10 and 240 n , p. 157), in which the whole receptacle of the inflorescence is 

 excavated, urn- wise, and becomes very succulent on ripening. The little grains inside, 

 commonly taken for seeds, are in reality the actual fruits or nuts, each of which 

 contains a seed. As a final instance may be mentioned the polygonaceous Brunnichia 

 africana from west tropical Africa; in this case the flower-stalk becomes winged 

 down either side, from its point of insertion up to the nut at its apex. It thus serves 

 as a distributing organ for the fruit. 



In many plants whose flowers are clustered very close together it often happens 



Fig. 329. Fruits with Cupules 

 i Quercus pedunculate,. 2 Quercus sessUiflora. 



