88 



FRUIT. 



in the Lilac, Gladiolus, &c. (Fig. 141.) Septifragal dehiscence 

 is when the dissepiments separate from the valves, but adhere 

 to the axis, as in the Convolvulus. (Fig. 142.) In sutural de- 

 hiscence there is but one carpel, and of course no true dissepi- 

 ments, as in the Pea and Bean. The circumscissile dehiscence 

 occurs by a transverse separation of the valves half round the 

 pericarp, as in the Anagallis. This is an uncommon mode. 

 The Plantago has a transverse dehiscence. 



Besides the above modes of opening, the pericarp is often 

 ruptured, produced by a contraction of a portion of it, and 

 holes thus formed for the emission of the seed, as in Campan- 

 ula. An aril is an enlargement of the placenta, occurring after 

 the impregnation of the ovule, and forming, in some cases, an 

 additional envelope for the seed, as in the Euonymus. Mace is 

 an -aril surrounding the Nutmeg. When the two sutures sepa- 

 rate from the valves, they form a kind of frame called replum. 



151. Fruits are formed by one flower, or they may be formed 

 by the combination of several flowers. Apocarpous fruits, pro- 

 duced by a single flower, may be either dry or succulent. The 

 dry fruits of this division are either dehiscent or indehiscent. 



An Achenium (a, privative, and chaino, I open) is an inde- 

 hiscent, one-seeded fruit, the pericarp of which is closely ap- 

 plied to the seed, but may be separated from it. (Fig. 143.) 

 The true achenia are found in the Ranunculus, forming a dry 



Fig. 143. 



Fig. 145. 



Head of Ranunculus. Samara. 



head (Fig. 144); in the Strawberry, arranged on a fleshy re- 

 ceptacle ; in the Rose they are found in a concave receptacle ; 

 in the Fig, in a hollow peduncle, which ultimately becomes the 

 fruit. All the fruits mentioned, which are commonly called 

 seeds, may be distinguished from the seeds by bearing the 

 marks of the stigma or style. In composite, the seeds are 

 called CypselcB {kupsele, a box) ; but they are achenia with the 

 calyx attached to them. 



When the achenium is winged, it is called a Samara. (Fig. 



Septifragal? Sutural? Circumscissile? Ruptured? What is an aril? 

 A replum ? — 151. How may fruits be formed? What is an achenium? 

 Where are they found ? What is a cypsela ? A samara ? 



