THE FRUIT AND ITS ENVELOPES. 



93 



at tlieir summit by teeth, which are at first close 

 together, but which separate from each other, as 

 in many caryophylleae ; 4thly, Those which 

 separate into a determinate number of distinct 

 pieces, which are named valves. These latter 

 are the truly dehiscent pericarps. The number 

 of valves in a pericarp may always be learned 

 by the number of longitudinal seams or sutv/res, 

 which are observed upon its outer surface. The 

 true valves are of the same number as the cells 

 of the pericarp. Thus a dehiscent fruit, which 

 is qiiadrilocular, has fimr valves. There are 

 some exceptions, however. The capsule of the 

 violet is a single cell, and opens into three valves. 

 In some fruits, each of the valves separates into 

 two pieces, so that the number of the former 

 seems double what it ought naturally to be. 



A pericarp is called bivalve, when it separates 

 of itself into two equal and regular valves ; as in 

 the lilac, and the speedwells. Trivalve, when 

 it opens into three valves ; as in the tulip, the 

 lily, the violet. Quadrivalve, or with four valves; 

 as in the genus epildbivm, and the thorn-ap- 

 ple. Qttinqztevahe, opening with five valves. 

 Multivahe, when it divides into a greater number 

 of valves or distinct segments. 



The opening of the valves may take place in 

 diflFerent ways, agreeably to the relative position 

 of the valves and partitions. It may take place 

 at the middle of the cells, or between the parti- 

 tions which then correspond to the middle part 

 of the valves. This is observed in most of the 

 ericinese. At other times the opening takes 

 place opposite the partitions, which it usually 

 divides into two laminae ; as is seen in the scro- 

 phularinese, and rhodoraceae. Lastly, the burst- 

 ing may take place towards the dissepiment, 

 which remains free and entu-e at the moment 

 when the valves separate; as in the Mgnonice 

 and calluna vulgaris. Most commonly the open- 

 ing takes place by longitudinal sutures. In 

 some cases, however, these sutures are trans- 

 verse, and the valves are superimposed upon 

 each other ; examples of which are seen in the 

 henbane, the pimpernel, and the plantain. The 

 fruit may be crowned by the teeth of the calyx, 

 when the ovary is inferior or parietal, as in the 

 pomegranate, the apple, the pear. At other 

 times, it is surroilnded by a tuft of bristly hairs 

 (the pappus), which is to be considered as a 

 true calyx. This is the case in almost all the 

 species of the extensive tribe of synantherese. 



The pappus may be sessile, or applied directly 

 upon the summit of the ovary, without the aid 

 of an intervening body ; as in the genera hiera- 

 cium, sonchus, prenanthes, fig. a. In other geiiera, 

 it is supported upon a small pivot or stalk, which 

 is named the stipe, and the pappus is said to be 

 stipitate, as in the lettuce and dandelion, &c., 

 fig. b. The hairs of which the pappus is com- 

 posed, may be simple, or undivided, in which 



case the pappus is said to be pilose or hairy. At 

 other times they are feathcrj/^ or ]iave on their 



sides other shorter and finer hairs, resembling 

 the barbs of a feather. The pappus is then 

 najaeA. plumose o^ feathery. 



In the valerians, the pappus, which is obvi- 

 ously nothing but the limb of the calyx, is at 

 first rolled up within the flower, and appears in 

 the form of a small circular rim at the upper part 

 of the ovary ; but, some time after fecundation, 

 it is seen to stretch out, elongate, and form a 

 true feathery pappus. 



The pericarp also not unfrequently presents 

 membranous appendages in the form of vnngs ; 

 as in the elm and maple. According to the 

 number of these appendages, it is named dipter- 

 ous, tripterous, tetrapterous, &c. Sometimes 

 it is covered with long, stiff hairs, as in lo-ntarusj 

 or is stuck over with spines, as in the horse- 

 chestnut and thorn-apple. 



As every fruit is composed of two parts, the 

 pericarp and the seed, we have first to distinguish 

 these two parts from each other. We know that 

 the seed is always contained within the pericarp. 

 If we cut a peach in two, we shall find its centre 

 occupied by a cavity or-cell, containing a single 

 seed, rarely two. The seed once distinguished, 

 all that is placed externally of it, according to 

 Richard, belongs to the pericarp, and he thus 

 enumerates its different parts. In the first 

 place, we find, at the outside of the whole, a 

 thin, coloured pellicle, covered with a very short 

 down, which is easily removed. This pellicle is 

 the epicarp. The internal cavity of the pericarp 

 is lined by a smooth membrane, intimately 

 united to, and confounded with, the hard part 

 which forms the nut or shell. This membrane 

 is the endocarp. AH the thick, fleshy, spungy 

 part, contained between the endocarp and the 

 epicarp, forms the sa/rcoca/rp. But to which ol 

 these three parts belongs the bony shell which 

 we observe within? Is it, as was long supposed, 

 a proper integument of the seed, a thick and 

 woody endocarp, or is it part of the sarcocarp ? 

 These questions can easily be solved by examin- 

 ing how this hard part is formed. If we take 

 a young peach, long before it is ripe, and cut it 

 through, we find no resistance, there being aa 

 yet no solid shell in it. At this period, the 



