520 



BOTANY 



PAKT II 



4. A BERRY is a fruit in Avhich all the layers of the pericarp 

 become succulent, as in Vaccinium, Vitis, etc. ; when at complete 

 maturity the succulent tissue dries up a dry berry results (Cajmaim). 

 In a few cases berries may be dehiscent, as in Myristica and some 

 Cucurbitaceae. 



5. In the DRUPE the pericarp is differentiated into a succulent 

 exocarp and a hard endocarp. Prunus Cerasus (Fig. 631), and Juglans 

 regia (Fig. 516), are familiar examples. 



. Fruits which do not originate from the ovary alone are found in Hosa (Fig. 

 490), in which the succulent receptacle protects the partial fruits and still bears 



the calyx on its margin, and in Physalis 

 (Fig. 489), the berry of which is enclosed 

 in the greatly enlarged calyx. 



When on the other hand the group of 

 fruits borne on an inflorescence has the 

 appearance of a single fruit the structure 

 may be termed a spurious fruit. The Fig 

 (Ficus) is the best-known example of this, 

 but similar spurioiis fruits are especially 

 frequent in the Urticaceae and Moraceae. 

 The comparison of a Blackberry which is 

 the product of a single flower with the 

 spurious fruit of the Mulberry will show 

 how closely the two structures may re- 

 semble one another (Fig. 491). 

 The above enumeration of the most important and frequently recurring forms 

 of fruit is in no sense exhaustive. It should be added that the various fornA are 

 only to be understood when regarded from an oecological point of view. The form 

 and other peculiarities of the fruit must be considered in relation to the distribu- 

 tion of the seeds. 



Fio. 491. — A, Meroearpic fruit of liiihus frutl- 

 cosus, consisting of a number of drupes ; 

 B, inflorescence of Mulberry (Moriis nigra) 

 beai'ing a number of small drupes. (After 



DOCHARTRE.) 



Distribution of Seeds (^'^) 



The most important means by which plants compete with others 

 living under the same conditions is to produce as many seeds as 

 possible. With the number of descendants the i^robability that some 

 at least will succeed is increased. The number of seeds by itself 

 would, however, be of little avail if all the seeds remained in the place 

 of their origin. Thus good arrangements for the distribution of the 

 seeds are of the greatest importance and the form and construction of 

 fruits and seeds exhibit the great influence of this factor. 



The same agents are available in the distribution of seeds as in 

 the conveyance of pollen — currents of air and water, animals, and in 

 addition human traffic. A distinction must be made, however, between 

 the conveyance of pollen and of seeds, in that while a pollen grain is 

 extremely small and weighs very little, seeds contain a certain amount 

 of reserve materials and are thus larger and heavier. In spite of this 

 the transport of seeds by the wind is the main means of their dispersal. 



