178 Fernald — Relationships of some American 



Betula alha, var. minor. 



The dwarf alpine shrub whicli was described bj Tuckerman 

 as Betula -papyracea, var. mino/\^ is represented in tlie G-raj 

 Herbarium by material from Tuckerman himself. It is not, 

 perhaps, the commonest dwarf Canoe Birch of the White 

 Mountains, but is a form with the small elliptic- or truncate- 

 ovate leaves strongly glutinous and quite without pubescence. 

 From the comparatively narrow wings of the samaras in Tuck- 

 erman's specimens, Eegel took the plant to be a form of 

 B. davurica^ Pallas, of eastern Asia, and upon the Tuckerman 

 sheet he based his B. davurica^ /9, ameTicana.^ The shrub 

 is, however, more properly a phase of B. alba^ and it occurs 

 likewise on the Xorth Summit of Mt. Katahdin, where it 

 sometimes has the leaves smaller firmer and more glutinous 

 than on Mt. Washington ; in Gaspe and in Labrador ; and in 

 the mountains of Saskatchewan, Assiniboia and Alberta, where 

 it intergrades with B. rnicropliylla. Though ordinarily dis- 

 tinguished from B. alba^ var. cordifolia^ by its elliptic- or 

 truncate-ovate glabrous leaves, smaller erect strobiles, and 

 smaller samaras, this second dwarf Canoe Birch shows ten- 

 dencies to integrade with that form. In its most characteristic 

 development this shrub of the JSTew England mountains 

 matches B. toHuosa^ Ledebour,:J: described from the Altai Mts. 

 of central Asia, where it had likewise been mistaken by Lede- 

 bour for B. davurica of Pallas. The range of Betula tortuosa 

 has since been extended through northern Russia to Silesia, 

 Finland, Lapland and Greenland, where it is sometimes treated 

 as a species, but by Koehne and by Guerke as a form of B. 

 alba {B. puhescens^ var. tortiiosa (Ledeb.) Koehne). § 



If we compare specimens collected by the late Edwin Faxon 

 at " Willis's Seat " on Mt. W^ashington, Xew Hampshire, and 

 Altai material of Betula tortuosa sent to the Gray Herbarium 

 from the Imperial Herbarium at St. Petersburg, we shall find 

 the former differing only in its glabrous branchlets. This 

 want of pubescence is, however, quite as conspicuous in a 

 Lapland specimen from Kegel of his B, alha^ subsp. tortuosa 

 a genuina. If, again, we compare the original sheet of Tuck- 

 erman's B. papyracea^ var. minor from the White Mountains 

 with the plate of B. tortuosa in Flora Danica (xvii, t. 2918) 

 we shall find them too close for ready separation. Specimens 

 from Mt. Katahdin are, furthermore, quite inseparable from Ro- 

 sen vinge's Ko. 160 from Greenland, distributed from the Botan- 

 ical Museum of Copenhagen as B. odorata, var. tortuosa and 

 represented by sheet Iso. 2,0ii in the Herbarium of the Geo- 

 logical Survey of Canada ; and various Mt. Washington speci- 



* Tack., this Journal, xlv, 31 (1843). f Kegel in DC, 1. c, 175 (1864). 



X Fl. Eoss. iii. 65.2 (1849). § Deutsche Dendr. 109 (1893). 



