376 MORPHOLOGY OF THE ANGIOSPERMS 



as "fleshy" and "dry." Most classifications of fruits have been prepared 

 for taxonomic purposes and, as such, are important. Classification of 

 fruits and descriptions of types are discussed here only in so far as they 

 have morphological and phylogenetic value. 



General structure of the gynoecium — apocarpous, carpels free from 

 one another, and si/ncarpous, carpels united with one another — is an 

 important basis for natural classification, because freedom of floral 

 organs is clearly a primitive condition. 



In an old, but still much-used, classification, fruits are classified as 

 simple, multiple, or aggregate. Simple fruits consist of one, or of several 

 united, carpels; multiple fruits consist of the gynoecia of more than one 

 flower, cohering or connate on a common axis; aggregate fruits consist 



of the carpels of one gynoecium, free in 

 "^ the flower but coherent in the fruit 



(Fig. 139). (The terms multiple and ag- 

 gregate are reversed in some defini- 

 tions. ) 



Fruits in which organs other than the 



carpels are present — receptacle, pedicel, 



\ inflorescence axis, sepals, bracts — are ac- 



r, ccssonj (Fig. 140). For example, the 



fruit of the pineapple. Ananas, is mul- 



/' tiple and accessory, consisting of an in- 



florescence axis, with many connate 



?'/ ovaries fused with the bases of their 



subtending bracts and with the axis on 



Y?- ion IT -^ r ^ which they are borne. The fruits of 



Fig. 139. Fruit or Annona sp. J 



Bromelia, a related genus, are free 

 and simple and without accessory parts. Opinions differ as to what con- 

 stitutes the accessory parts of a fruit. In some descriptions of the pine- 

 apple fruit, the bracts are omitted, but the bracts are intimately fused 

 with the flowers — even their vascular systems are partly united — and 

 their bases form part of the flesh. On the other hand, the burrs of the 

 beech and chestnut and the acorn cup — compacted, sterfle branches of 

 the inflorescence — are not considered part of the fruit, although, in 

 Quercus, the acorn cup is adnate to the ovary in varying degrees. 

 Morphologically, a limitation of "accessory" parts cannot be made. 

 Terms based on histological structure — dry, fleshy, stony, etc. — and on 

 method of dissemination have little or no morphological significance, 

 and lines between types cannot be drawn. The range in fruit within a 

 family may be great; in the Proteaceae, follicle, drupe, nut, and achene, 

 and, in the Rosaceae, many types. The fruit of the Ericaceae ranges 

 from dry to fleshy; that of Epigaea is a dry capsule, which opens at 



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