1692

ARBORETUM AND FRUTICETUM.

PART III.

sidered by many botanists as a species, anddistinct enough in appearance, we have nohesitation whatever in pronouncing it to bemerely a variety.

S B. a. 4 pbntica; B. ponticaLodd. Cat., ed. 1836;and our fig. 1549.; has the leaves somewhatlarger than the species, and appears of morerobust growth. There is a tree of this kind inthe Oxford Botanic Garden, which, 40 yearsplanted, is 45 ft. high; the diameter of thetrunk 1 ft. 11 in., and of the head 30 ft. AtCroome there is a tree, which, 40 yearsplanted, is 70 ft. high ; and in the GlasnevinBotanic Garden, one 35 j«ars old, which is38 ft. high. The plants in Messrs. Loddiges’scollection are quite young, and not above3 ft. or 4 ft. in height.

i B. a. 5 urticifolia, B. hrticifolia Lodd. Cat., hasthe leaves deeply laciniated, serrated, and hairy.

1549

B. a. 6 dalecarlica L. Supp., 416., is described by the younger Linnaeus, as having its leavesalmost palmate, with the segments toothed; “ cut like those of hemp,” according toBose.

¥ B. a. 7 tnacrocdrpa Willd. has the female catkins twice as long as those of the species.

^ B. a. 8 filiis variegatis Dumont has the leaves blotched with yellowishAvhite.

Other Varieties. B. yjopulifolia and B. daurica, given below as species,are, we think, as much varieties as the preceding sorts; for, though if.yjopu-lifoiia will come tolerably true from seed, yet it is often produced from seedsof the common birch. B. daurica appears to be a variety of B. alba, stuntedfrom the climate in which it grows; and the same observation will applyto B. sibirica, and some others, enumerated in the Catalogue of Messrs.Loddiges for 1836. B. excelsa and B. nigra of some of the London gar-dens are mere varieties of the common birch, and quite distinct from thespecies described by botanists under these names, which are natives ofAmerica. (See Gat'd. Mag., vol. xi. p. 502. 689.) There are some othersorts in the collection at Messrs. Loddiges’s; such as B. undulata, B.Thouin idna and B. Fischerii, which appear to us to belong to B. alba; but,the plants being exceedingly small, we are not able to determine this withcertainty. B. laciniata being merely a cut-leaved variety of A.yiopulifblia, wehave included it under that head; as we have the sort named B. pendula,in the collection of the Messrs. Loddiges. We prefer, in this case, as insimilar ones, giving varieties which have been generally considered speciesas such, merely indicating our opinion by a letter in parentheses, for thesake of disposing of the synonymes. There are some varieties of a triflingnature given by Linnaeus in his Flora Suecica : such as one with a rounderleaf than the species, and pendent branches ; one with a white, broad, andacuminate leaf; one with brittle branches, and a blackish woolly leaf; one( B . saxatilis torminalis) with an oblong leaf; and, lastly, the dwarf birch,probably the B. pumila of Lodd. Cat. These varieties are recorded inMartyn’s Miller ; but, unless we are right in conjecturing B. pumila to bethe last, we have not seen any of them. Dr. Agardh mentions “ threesingular varieties with laciniated leaves ( B . hybrida Moench) near Fahlun.( Gard. Mag., vol. xii. p. 63.) The birch varies so much from seed, thatscarcely any limits can be given to the number of sorts that might beselected from a seed-bed. In extensive birch forests, also, whether in therocky scenery of Sweden, the bogs in the north of Russia, or on the hills ofGermany, full-grown trees may be seen, as various in their foliage and habitof growth as the young plants in seed-beds. For this reason, we are in-clined to think that there are only two European species of birch, B. albaand B. nana; and four American species, B. papyracea, B. excelsa, B.lenta, and B. nigra.