CHAP. CIV.

netula'ceae. z?f/tula.

1707

tions that the leaves of B. nana vary exceedingly; in the marshes ofSiberia, especially near Lake Baikal, and in Lapland and the arcticregions, they are small, and not an inch in length ; but in Ingria , andthe alpine rocky situations of Dahuria, they are large, and frequentlybroader than they are long.

a 6. B. glandulo'sa Michx. The glandular-iraBc^ed Birch.

Identification. Michx. FI. Bor. Amer., 2. p. 180.; Willd. Sp. PI., 4. p. 466.; Pursh FI. Amer. Sept.,

2. p. 622.; N. Du Ham., 3. p. 208.

Spec. Char., fyc. Branches beset with glandular dots, glabrous. Leaves obovate, serrate, quite entireat the base, glabrous, almost sessile. Female catkins oblong ; scales half 3-cleft. Seeds round,with narrow margins. {Willd. Sp. PL, iv. p. 466.) A handsome little shrub,not above 2ft. high ;found in Canada, about Hudson’s Bay, and on the borders of lakes on the high mountains of NewJersey and Pennsylvania ; flowering in May. (Pursh.) It seems to correspond, in America , withthe B. n£na of Europe , and is probably only a variety of that species. It is not yet introduced.

Leaves large . Natives of North America .

^ 7. B. (a.) .fopulifo'lia Ait. The Poplar-leaved Birch

Identification. Ait. Hort. Kew., 3. p. 336.; Willd. Sp. PI., 4. p. 463. ; Baum., p. 55. ; N. Du Ham.,

3. p. 204. ; Du Roi Harb. Baum., 1. p. 144.; Marshal, p. 36.; Pursh FI. Amer. Sept., vol. 2.p. 620.; Michx. N. Amer. Syl., vol. 2. p. 97.

Synonymcs. B. acuminata Ehrk. Beit., 6. p. 98.; B. lenta Du Roi Harb. Baum., ed. 1., p. 92.,Wang. Beit., p. 45.; white Birch and Oldfield Birch, Amer.

Engravings. Michx. Arb., 2. p. 139. t. 2. ; Willd. Baum., 1.1. f. 5. j Michx. N. Amer. Syl., vol. 2.t. 71.; and our fig. 1560.

Spec. Char., fyc. Leaves deltoid, much acuminated, unequally serrated, quitesmooth. Scales of the strobiles having roundish side lobes. Petiolesglabrous. {Willd. Sp. PL, iv. p. 463.) A tree, in every respect closelyresembling B. alba, but growing with less vigour, and not attaining so largea size as that species. A native of North America .

Varieties.

i B. (a.) p. 2 laciniata, B. laciniata Lodd. Cat. , ed. 1836, has large,smooth, shining, deeply cut leaves, and appears to us to belong toB. (a.) ympulifdlia, rather than to B. alba,i B. (a) p. 3 pendula, B. pendula Lodd. Cat. , ed. 1836, has the spraydrooping, like that of the weeping variety of the common birch; butwhether equally distinct or not, we have been unable to determine,from the very small size of the plants in the London collections.Description. The poplar-leaved birch, according to Pursh, is a tree from30 ft. to 40 ft. high ; but, according to Michaux,it only attains this height in favourable soilsand situations. On trees that are fully grown,die branches are numerous, slender, and droop-mg. The leaves are smooth on both surfaces,heart-shaped at the base, very acuminate, anddoubly and irregularly toothed. The petiolesare slightly twisted ; and the leaves are thusrendered more tremulous than those of treeson which this disposition is not observed. Thebuds, a few days after their developement, areslightly coated with a yellowish odoriferoussubstance, like those of B. alba. The trunk ofthis species is clothed in a bark of as pure awhite as that of B. papyracea and B. alba;but its epidermis, when separated from thecellular integument, is capable of being divided,

•ike that of B. nigra and B. excelsa, into thinsheets, which constitutes an essential difference.

{Michx. N. Amer. Syl., ii. p. 98.) The treeis indigenous to barren rocky woods and oldnelds, from Canada to Pennsylvania . It isra re m Virginia, and does not exist in the other southern states. It ismost frequently found in places scantily furnished with wood, where the