THE ANGIOSPERMAE 



1543 



as the Mulberry, the Moraceae. One genus of Moraceae, Dorstenia, has 

 its flowers set upon the upper surface of a flat, expanded axis, while in 

 Ficus the axis has been not only expanded but curved upwards into a hollow 

 flask with a tinv orifice, on the inner surface of which are set the numerous 

 small flowers. This peculiar structure is called a sycomis (Fig. 1404). The 

 pollination and the sex relationships of the flowers of Ficus have already 



Fig. 1404. — Ficus carica. Fig. Longitudinal 

 section of a young syconus showing the 

 interior layer of flowers, with a cluster of 

 sterile flowers round the orifice. 



been described (p. 1327). The genus is a very large one with a world-wide 

 distribution in hot countries, but the syconus fruit is its constant character- 

 istic. Similar but much less well-known syconus fruits are found in the 

 Monimiaceae. 



When the carpels of an apocarpous flower ripen separatelv they form 

 an etaerio, which is the collective name for the group. Thus there may be 

 in Ranunculaceae an etaerio of akenes or an etaerio of follicles. If, how- 

 ever, during ripening they become so closely crowded that they form a 

 coherent structure the product is called an aggreaate fruit. Examples of 

 such aggregates are provided by the Raspberry and the Blackberry, both 

 species of the genus Rubus (see Fig. 15 14). The various cultivated species 

 of the genus Annona also form aggregate fruits, i.e.. Custard Apple, Sweet 

 Sop, Sour Sop, etc. Magnolia and Cornus provide other well-known 

 examples (Fig. 1405). The individual portions of the Rubus fruit are drupes 

 or drupels (diminutive) but in Annona the individual fruits are completely 

 fused into a fleshy mass and have no separate existence, though bv analogy 

 they may be described as one-seeded berries. 



The term collective fruit is apphcable to compound fruits made up of the 



