ACCESSORY STRUCTURES OF FRUITS. 



435 



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

 attached. Finally, in the Hop-hornbeam {0strya,6g. 437^) 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 Pomaceaj. In the Carolina Allspice (CalycantJms, figs. 328 i 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 liearing a five- 

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

 PomacesB, the i-eceptacle forms an extremely succulent mass, in which the actual 



fruit is imbedded, and 

 with which it is entirely 

 fused (e.g. Quince, Gy- 

 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 ' 

 and 328 ^) 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 Anacardiaceas, in some Rhanmacese, and in a few 

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

 cardium occidentale, fig. 330 ^), 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 (Ficiis, cf. 

 figs. 240 ^° and 240 ^^ 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 polj'gonaceous Brun nichia 

 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 

 * Quereus peditnculata. 2 Q^tercus sessilifiora. 



