Miscellaneous. 



386 



[June 1907. 



Lessons in Elementary Botany. X. 



By J. O. Willis. 



The Fruit. The ovule is usually enclosed in an ovary, and these parts 

 are stimulated to further growth by the act of fertilisation and develope 

 together with the ripening seed, finally forming a covering to it known as 

 the fruit. 



Usually the seed is enclosed in an envelope or pericarp, derived 

 from the ovary, but in some plants it is naked or nearly so. The calyx or 

 bracts often persist and surround the fruit, as may be well seen in the Cape 

 gooseberry. 



Fruits may be divided first of all into simple (fig. 6,) aggregate (fig. 7,) and 

 multiple. Where a flower gives one indivisible fruit, the fruit is simple, as in 

 cherry or oak ; where it gives several similar fruits, independent of one another, 

 as in raspberry, buttercup, Ochna, &c. the fruit is aggregate ; where several 

 flowers combine to give one fruit, as in mulberry, fig, plane, the fruit is 

 multiple (or collective). In description, mention is made of the multiple or 

 aggregate nature of the fruit and then one of the units is described as if it were 

 a simple fruit. 



Fruits may be dry or fleshy ; they may open to allow the seeds to escape 

 {i.e. may be dehiscent) or may remain closed (indehiscent). Indehiscent dry fruits 

 are usually one-seeded ; it would be a disadvantage to have many seeds germinating 

 near together. Fleshy fruits rarely dehisce ; they are eaten by animals and the 

 seeds are thus separated. Some dry fruits, termed schizocarps, break up into one- 

 seeded portions, or mericarps, usually corresponding to the individual carpels. 



Dry indehiscent fruits are usually divided into achenes and nuts, and in 



practice small ones are called achenes (fig. 8) and large ones nuts. They are some- 

 times provided with a wing on one side (fig. 9). 



Schizocarps (fig. 11) are common in Ceylon, and a very common type is the 

 lomentum, as it is often called, of many Leguminosae, such as Acacia decurrens, a 

 pod which breaks up between the seeds (fig. 10) 



Dry dehiscent fruits are of many kinds, and the commonest sorts are the 

 follicle (fig. 12), legume or pod (fig. 13), and capsule (fig. 14). The first consists of one 

 carpel only, and opens only along one side ; the second also of one carpel, but opening 

 along both sides (it is this fruit which characterises the great family Leguminosae). 

 The capsule is a dry fruit of more than one carpel, and usually opens by splitting 

 between the carpels in various ways, but may open, as in the poppy (fig. 14) by 

 pores, usually under an overhanging roof that keeps the rain out. The portions 

 into which a capsule splits are termed valves. 



The commonest fleshy fruits are the berry and drupe ; in the former the 

 only hard part is the seed or seeds ; in the latter, e.g. the cherry (fig. 16), the seed 

 or seeds are enclosed in a shell or shells formed of part of the fruit tissue. There 

 are many peculiar kinds of fleshy fruits in addition, e.g. the strawberry (fig. 17), 

 which is a fleshy receptacle bearing achenes, the cashew-nut (fig. 18), '„ which is a 

 fleshy receptacle bearing a nut, and so on. 



The style and stigma usually fall away as the fruit ripens, but may harden 

 nto a thread-like organ on the fruit, which is known as an awn (fig. 19). 



