FRUIT 



19 



carpellary leaves U delayed until the growth- 

 jinicfsses of the seed ami fruit have ended, and it 

 is therefore accompanied, or even preceded, l>v their 

 <lf.it It; the separation often indicating the lines at 

 mice of leaf-margin and leaf-fall. 



In the }>*( de\ eloped oarpellary leaves, such as 

 tlin-i- -if i IK- more lloral RanuncmMMB, we natur- 

 ally lind the ovary 'dehiscing along the ventral 

 sui ure '--in more simple and less empirical Ian- 

 giiage, the carpellary leaf opening along the line 

 of its united ovule -hearing margins. This is what 

 is termed a, follicle (lig. \,f). 



Since, however, the ovules are on the united 

 in. 1 1 -in-, the mnli il> tends to become mechanically 

 unimportant, and to interpose little or no resist- 

 ance to a tendency to split or tear along its fold, as 

 well as to open along the united margins. Such 

 ' dehiscence by both dorsal and ventral suture' 

 gives us the modification of the follicle known as a 

 legume or putt (fig. 1, e). 



A very familiar type, which must not be confused 

 with the pod, is the siliqtia (or when shortened and 

 broadened the silicula) of Cruciferne. Here the 

 placental edges of two united carpels develop a 

 tran-vei-e septum which divides the fruit ( tig. \,d); 

 and this is left when the lobes split away, as so 

 familiarly in Honesty. 



Among united ovaries which readily split open 

 at the united margins (septiculal) we may note 

 that of Gentian (q.v.), while the more familiar 

 three-celled ovary of a violet (fig. 1, b) or rock 

 rose with its parietal placentation gives a charac- 

 teristic example of dehiscence along the midribs of 

 the united carpels, so opening the loculi (loculi- 

 cidal). In the live-celled capsule of the Geranium 

 (q.v.) the carpellary leaves separate not only at the 



Fig. 1. 



/, follicle; e, legume; d. silio ila; c, capsule of henbane; 

 b, of violet ; a, of poppy. 



sides but also at the base, so curling inwards and 

 projecting the seed. In Colchicum, white hellebore 

 (Veratrum), and their allies (MelanthacejB) the 

 ilehiseence is characteristically septicidal, the 

 carpels separating instead of the loculi opening : 

 the remaining majority of Liliaceae are loculicidal. 

 Where, however, the placentae remain more or less 

 completely upon a central column from which the 

 valves are detached, the dehiscence is said to be 

 xi'/if i frugal. 



In henbane (fig. 1, c), Anagallis, &c. the dehis- 

 cence is circular (circumseissile); the possible ex- 

 planation of this as a dwarticulation of the united 

 carpels by their leaf-bases is, however, rendered 

 difficult through the separated portion being a mere 

 lid. Many-celled capsules are numerous in which 

 the leaf-opening or dehiscence is greatly reduced 

 from completeness, witness the rnlrulnr &nd porous 

 dehiscence of the Lychnis and of the poppy ( lig. 1, a ) 

 respectively. Such cases clearly point us to those 

 of carpels which do not open at all. Such ///</<- 

 hiscent fruits, produced from carpels so persistently 

 embryonic, are, as we might expect, usually 

 short, few or one-ovuled, and, for the most part, 

 little specialised. Thus the follicle of the Ranun- 

 more specialised floral character becomes 



shortened into the one-seeded indehiscent ac/tene 

 of the anemone or buttercup (fig. 2, e, f). In 

 the achene of the grasses (which similarly repre- 

 sents the capsule of the ancestral lilies) the 

 thin dry pericarp Incomes inseparable from the 

 seed-coat (hence the term caryopnui, fig. 2, c, d) ; in 

 many trees (e.g. hazel) it Incomes hardened and 

 thickened as a nut. In composites (lig. 2, a, b), 

 too, the achene is practically a nutlet, although 

 often (on account of its being inferior) termed a 



Fig. 2. 

 e,f, achenes of buttercup ; c, d, caryopsis of oat ; a, b, aclienes with 



n>pus ; g, ' lomentum ; ' t, h, nutlets and ovary of borage ; 

 , umbelliferous type of schizocarp. 



cypsela. Less extremely reduced representatives of 

 the various multicellular ovaries to which such 

 fruits correspond are afforded us by borages or 

 labiates, in which the two-celled ovary of the primi- 

 tive solanaceous type becomes, as in thorn-apple, 

 &c., subsequently divided into four parts : these 

 (see fig. 2, /, h), however, are here so arrested as 

 only to develop a single ovule in each loculus (of 

 which the subsequent growth brings about the 

 perplexing appearance of the 'gynobasic 1 style). 

 The four ripe ' nutlets ' into which the four-lobed 

 ovary of these forms commonly breaks up were not 

 unnaturally mistaken by the old botanists for naked 

 seeds. In Umbelliferse we have another charac- 

 teristic form of schizocarp, as all such fruits are 

 termed which split up without truly carpellary de- 

 hiscence, although the tendency to this can be seen 

 still to have some influence. Here the separate 

 portions (or m-ertcarps), each resembling an achene 

 or nut, are two in number, and when ripe swinjj; off 

 upon the ends of a forked carpophore (fig. 2, /, /.). 



In exceptional cases we have the pod of some 

 Leguminospe and the siliqua of some Crucifers e.g. 

 radish, snapping off into one-seeded joints, instead 

 of dehiscing longitudinally in the regular way. This 

 simply comes about where the swellings correspond- 

 ing to the seeds become unusually large, leaving^ 

 narrowings between them, and thus giving the pod 

 a strength of form too great for the usual tension of 

 ripeness to overcome (fig. 2, g). To confuse such 

 distinct types of fruit under a common term (loiiieti- 

 tinn ), and to separate them from the normally 

 dehiscent capsules to which they really belong, and 

 to place them among the purely 'schizocarpous' 

 fruits we have been describing, although still too 

 customary, are merely examples of the reasoned 

 mistakes inseparable from a purely descriptive 

 anatomy, but from which the evolutionary stand- 

 point is at length delivering us. 



So far all our fruits have been dry ; but a new 

 physiological * principle of fruit-making ' is neces- 

 sary to comprenend those in which the pericarp is 

 succulent. For, just as the effect of fertilisation is 

 seen in many animals to extend lieyond the mere 

 ovum to the parent organism, and also in many of 



