226 



NATURAL HISTORY OF PLANTS. 



Corylus Avellana, 



anther, dehiscing by a longitudinal cleft.^ The female flowers are 

 disposed in a very short bud-like catkin (fig. 172), with alternate 

 and imbricate bracts, few in number. In the axil of each of these 

 are found the flowers, arranged in pairs and surrounded each by an 



involucre covered with hairs, 

 formed by the lateral second- 

 ary bract, here more or less 

 deeply cut and finally sur- 

 rounding the floral receptacle. 

 The latter has the form of a 

 sac with narrow opening, en- 

 closing in its cavity the ad- 

 nate ovary surmounted by a 

 small annular calyx, very 

 short, epigynous and sur- 

 rounding the base of a style 

 soon divided into two large sub- 

 ulate stigmatiferous branches, 

 coloured red.^ In the inferior 



Fig. 172. Female in- 

 florescence (f). 



Fig. 173. Young fruit, 

 long. sect. X\). 



ovary,^ there were originally 

 two parietal placentee uniting along the axis of the cavity to form 

 two cells, each of which might bear two ovules ; but ordinarily in 

 the adult flower, each cell contains only one descending anatropous 

 ovule,^ with micropyle directed upwards and outwards.^ The fruit, 

 around which the secondary bract, forming the involucre, has taken 

 the form of a long green sac, is an achene the pericarp of which, 

 dry and indehiscent, unilocular and monospermous,^ is formed partly 

 of the hardened walls of the receptacular pouch ; it is crowned with 

 the scars of the style and calyx. The descending seed, surrounded 

 by a soft disconnected"^ tissue, encloses under its coats a large fleshy 



1 According to H. Mohl. the pollen is similar 

 to that of the Betulem. Its spherical granules 

 open hy three pores (Hass- Ann. cduI Mag. Nat. 

 Hist. ix. 556). 



■■^ It is the only portion of the female flower 

 which exists at the period of floration. 



^ Not formed till much later, near the middle 

 of spring. 



■* Strictly there may he four ovules, two on 

 each placenta, two of which are sooner or later 

 arrested in their development. The two ovules 

 which remain may helong to the same placenta ; 

 but more frequently they are inserted on sepa- 

 rate placentae, and correspond each to a dijSerent 



cell. Very rarely the two persistent ovules are 

 found inserted on different placentae and yet 

 correspond to one and the same cell. 



^ They have only one envelope. 



^ It is often dispermous ; hut one of the seeds 

 is sometimes reduced to small dimensions. 



7 This tissue, originally white and firm, but 

 which becomes thin and brown in the ripe 

 fruit, traversed by a central vertical fascicle, 

 is not developed in the cavity of the cell of 

 which it occupies the upper part, it is a hyper- 

 trophiate layer of the pericarp itself, i.e. of the 

 floral receptacle. 



