434 



FERTILIZATION AND FORMATION OF FRUIT IN PHANEROGAMS. 



fruit. In the Winter Cherry (Physalis Alkekengi), a solanaceous plant often culti- 

 vated in gardens, the calyx, originally small and green, becomes much inflated 

 during ripening and forms a bright red bladder inclosing the actual berry; in the 

 Henbane (Hyoscyamus), belonging to the same family, the calyx tightly incloses 

 the capsular fruit, its periphery forming a characteristic funnel around the top. In 

 Labiatse the calyx persists as a short tube, or as a bell or pitcher, at the base of 

 which the actual fruit is found. In the Water Chestnut (Trapa natans, cf. vol. i. 

 p. 607, fig. 144 ^) the four segments of the calyx become hardened and persist as four 

 spines arranged cross-wise around the fruit. In many Valerians, Composites, and 

 Scabiouses, the calyx persists, growing, as the fruit ripens, into a radiating crown 



• The Carolina Allspice {Calycanthv 

 the same. (After Baillon.) 



Fig. 328.— Fruits with persistent receptacles. 

 - Longitudinal section of the same. » Fruit of Agrimonia. 



Longitudinal section of 



of bristles or feathery hairs. This crown, known as a Pappus, serves the achene as 

 a parachute (cf. figs. 326 ^' ^' ^ and fig. 447). 



Amongst the Amentacese, trees whose flowers are for the most part destitute of 

 perianth, the bracts and bract-like scales associated with the flowers often play a 

 prominent part in the fruit. In the Grasses also the same feature is noticeable. 

 In these latter the actual grain is very frequently closely enwrapped by one of the 

 glumes, so tightly indeed, that they easily escape observation, as in Barley, Oats, 

 and many others. The greatest variety of fruit-investment is met with in the 

 Cupuliferse and allied Amentacese, which include the Hornbeam, Hop-hornbeam, 

 Beech, Hazel, and several other well-known trees. The actual fruit in all these is 

 a nut, but inclosed in a peculiar involucre-like sheath (the cupule) derived from 

 bract-like scales external to the flowers. In the Oak (Quercus) the cupule is cup- 

 like (figs. 329 ^ and 329 -); in the Beech (Fagus) it completely envelops the paired 

 triangular nuts, and is spiny outside, at ripening it bursts into four valves like a 

 capsule; in the Chestnut (Castanea) it is extremely prickly, and, as in the Beech, 

 bursts into valves (fig. 339^); in the Hazel {Corylus) it forms a laciniated, leathery 

 envelope to the nuts (fig. 235, p. 147), whilst in the Hornbeam (CarpAnus, fig. 327) 



