862 



ARBORETUM ET FRUTICETUM BRITANNICUM. 



diges's collection (the most complete in Europe, unless we except that of M. 

 Vilmorin,) are propagated by grafting on the common oak, close to the 

 ground ; and largely earthing up the grafts afterwards, so as to leave only the 

 points of the scions exposed to the air. This earthing up not only preserves 

 a uniform degree of moisture round the graft ; but the earth employed being 

 taken from the adjoining surface, and consequently having been heated by the 

 sun, produces an immediate increase of temperature round the graft, which 

 gives an impulse to the rising sap, and so accelerates vegetation. We had the 

 advantage, in August, 1840, of examining all the American oaks in the Bois 

 de Boulogne, in company with M. Michaux, who sowed the acorns in 1822 ; 

 and we there observed, as we had previously done in the Hackney Arboretum, 

 that much the most rapid, vigorous, and erect growing species was Q. pa- 

 lustris ; next Q. coccfnea, which resembles Q. palustris, but with leaves on a 

 larger scale ; then Q. rubra ; and, next to that species, Q. nigra and Q. tine- 

 toria. Q. alba is not in the Bois de Boulogne, the acorns, as M. Michaux 

 informed us, rarely retaining their vitality during the time requisite 20 years 

 ago to bring them to Europe. 



iii. A'lbce. White American Oaks. 



Sect. Char. Leaves lobed, and sinuated, not mucronated ; broadest at the 

 upper extremity ; dying off more or less shaded with a violet colour. Bark 

 white, or whitish brown, cracking and scaling off in thin laminae. Fructifi- 

 cation annual. Cups imbricate or echinate. Nut oblong, generally large. 



3f 8. Q. A'LBA Lin. The American white Oak. 



Identification. Lin. Sp. PL, 1414. ; Pursh, vol. 2. p. 633. ; Michx. Quer., No. 4. t. 5. 



Synonymes. Q. alba virginiana Park. T/ieat. Sot. ; Q. a. pinnatifida Walt. Carol, p. 230. No. 10. ; 



Q. paltistris Marsh, p. 120. No. 3. ; Chene blanc de 1'Amerique, Fr. ; weisse Eiche, Ger. 

 Engravings. Cat. Carol., 1. t. 21. f. 2. ; Michx. N. Amer. Syl., vol. 1. 1. 1. ; the plate of this tree in 



Arb. Brit., 1st edit., vol. vii. ; and our fig. 1569. 



Spec. Char., Sfc. Leaves oblong, pinnatifidly serrated ; pubescent underneath : 

 lobes linear-lanceolate, obtuse, entire, attenuated at the base. Fruit pedun- 

 culated. Calyx somewhat cup-shaped, warty, and flattened at the base. 

 Acorn oval. ( Willd.) A large deciduous tree. North America. Height 

 60ft. or upwards. Introduced in 1724. Flowers greenish white ; April. 



Varieties. The elder Michaux gives the two following forms of this species, 

 the leaves of both of which are shown vnfig. 1567. copied from Michaux's 

 Histoire des Chenes Ameriques : 



$ Q. a. 1 pinnatifida Michx. (Hist, des 

 Chenes Amer., t. 5. f. 1. ; and our fig. 

 1567. a.) Q. alba Ban. Cat. Stirp. 

 Virg. ; Q. virginiana Catesb. Carol, i. 

 p. 21. t. 21.; Q. a. palustris Marsh. 

 p. 120. No. 3. The usual form of 

 the species, and com- 

 mon from Canada to 

 Florida. Fig. 1568. 

 is a sprig and acorn 

 of Q. alba pinnati- 

 fida, taken from Mi- 

 chaux's North Ameri- 

 can Sylva, vol. i. t. 1 . ; 

 and the acorn without 

 its calyx is shown in 

 fig. 1566. at a. 



Q. a. 2 repdnda Michx. (Hist, des Chenes, t. 5. f. 2. ; and our fig. 

 1567. b. Found wild in the forests of Carolina, and sometimes oc- 

 curring in seed-beds of Q. alba in Europe. Fig. 1569. is from a sprig 



pinnatifida. 



. Q. a. pinnatifida. 



