BRITISH OAKS 39 
SUMMARY. 
1. There are two Lees of Oak, Q. Robur and Q. sessiliflora, 
native to the Britis 
a native tree ae. Robur occurs abundantly on the 
following soils :—(a non-caleareous : deep gravels, sands, and 
clays; (b) calcareous: deep marls, and on stern marls over 
newtans and (most rarely) chalk, and on fen 
. As a native tree, Q. sessiliflora occurs atamaane tly on shallow 
non-caleareous abil less frequently on shallow calcareous soils, 
and locally on deep dry sandy soils. 
ach SEOs. x sometimes dominant in wet woods, and 
sometimes in dry w 
5. The gekatingl limit of Q. Robuwr in the south of England is 
on a ft. (268 m.), and about 600 ft. (182 m.) in the north of 
50. sessiliflora is dominant in woods up to about 1000 ft. 
(302. m.) on hills in Britain, especially in the west and north. 
Above that ghutude, 3 it occurs rarely up to about 1200 ft. (863 m.). 
7. Q. Robur and Q. sessiliflora produce a natural fertile hybrid 
whose occurrence in Britain is widesprea 
. lanuginosa has been recorded from Ne asaats but the 
records are of an extremely questionable na 
9. Q. Cerris is frequently planted in England, and in a few 
cases it has established itsel? from self-sow 
10. The difficulties which many botani ae and foresters have 
hitherto experienced in correctly relating the native British Oaks 
are attributable to the following causes :— 
(a) The incorrect descriptions in the standard works of 
ce. 
(6) The failure to appreciate the amount of variation in the 
lengths of the peduncle and petiole of both Q. Robur 
and Q. sessiliflora. 
(c) The failure to realize the constancy of the presence of 
leaf-auricles in @. Robur and of multiple hairs in Q. sesst- 
(d) The hitherto unsuspected and widespread occurrence of 
the Hybrid Oak in Britain 
(e) The extremely ey ae state of the synonymy of the 
species, and the absence of type-specimens in herbaria. 
EXPLANATION oF PxatE 502. 
Quercus Robur x sessiliflora (drawn f ture by Mr. E. W. Hunnybun). 
1. Flowering branch. 2. i leaf (upper surface). 3. Mature leaf (lower 
4. Mature leaf (upper surface). 5. Infructescence. 1-5, } nat. size. 
s 
6. Portion of leaf (lower surface), x 5. 1 and 2 drawn from . gE 
ere in aed ne ot oat specimen gathered October, 1909. All 
