372 



BRITISH FLOWERING PLANTS 



The scales which protect the bud of Castanea are connate 

 stipules. This is indicated by the indentation at the 

 apex (Fig. 269), and the bud at the base. 



QuERCUs (Oak) 



Monoecious. Male flowers in slender pendulous 

 catkins, with 6-12 stamens; female flowers solitary or 

 clustered. Pollen wind-borne. Accord- 

 ing to Kerner the trees are protogynous. 

 Q. Robur. — Two forms are often re- 

 garded as distinct species — (l) Q. Rohlir, 

 var. jyedunculata, which has the leaves 

 sessile or shortly stalked, and the fruits 

 above the middle of a peduncle from 

 1 to 5 or 6 inches long ; and (2) Q. 

 Rohur, var. sessilijlora, with leaves on 

 foot - stalks half an inch to one inch 

 long, and fruits either sessile or on 

 a peduncle rarely attaining an inch in 

 length. 



The leaves are pubescent when young, 

 but afterwards glabrous. There are said 

 to be about 500 

 species of insects 

 which live on the 

 Oak, in which con- 

 nection we may men- 

 tion the familiar Oak- 

 apples, the result of 

 an irritation set up 

 by a gall-insect. The cotyledons are 

 subterranean, and the first few leaves 

 are small scales. This is probably an 

 advantage, as enabling the stem to 

 grow longer and thus carry up the first 

 foliaceous leaves above the surround- 

 ing herbage. The same reduction 

 of the first few leaves to scales occurs in several other 



Fia. 270.— Shoot of 

 Oak. Nat. size. 



Fig. 271.— Oak bud, 



