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MINNESOTA BOTANICAL STUDIES 



thick ; bracts 5-6 mm. long, 3-5 mm. wide ; samara 3.3 mm. wide, 

 nutlet slightly wider than the wing. (Fig. 1, f-g. fig. 2, k-1.) 



We are inclined to regard this form as belonging to the F. gen- 

 eration standing much closer to the B. papyrifera parent than the 

 ordinary hybrid, in its larger size, the character of the bark, the 

 coarseness of leaf serrations, and the size of the fruiting catkins 

 and the length of their pedicels. 



Only two trees of this variety have been found, both growing in 

 a small tamarack swamp near the center of Hennepin County 

 (Rosendahl Nos. 2685, 2686, 2731, 2732). 



Betula lutea x pumila var. glandulifera n. hybr. 



A shrub or shrub-like tree 3 to 6 m. high with grayish-brown 

 bark, not separating into layers, inner bark with wintergreen flavor ; 

 young twigs puberulent or thinly pubescent, with a few small resin 

 glands, 1-3 year old twigs gray-glaucous, changing to grayish- 

 brown on older branches ; spur shoots numerous with closely 

 crowded leaf scars ; leaves ovate to obovate. with 5-7 i)airs of 

 veins, slightly cordate to broadly cuneate at the base, acuminate at 

 the apex, 2.5-6 cm. long, 1.5-3.5 cm. wide, dull green and glab- 

 rous above, much lighter and at first pubescent along the veins 

 beneath, soon becoming nearly or quite glabrous, often glandular- 

 dotted, mostly unevenly and sharply serrate to crenate-serrate, thick 

 and firm in texture ; petioles stout, 7-14 mm. long with a few scat- 

 tered hairs ; staminate catkins borne singly or in pairs at the ends 

 of the branches. 3-5 cm. long in anthesis. about 5 mm. in di- 

 ameter ; pistillate catkins erect, sessile or nearly so, about 10 mm. 

 long, 2-2.3 mm. thick ; fruiting catkins oblong ovoid, 1.5-2.8 cm. 

 long, 10-12 mm. in diameter, erect, pedicel 3-8 mm. long: bract 

 5.4-7 mm. long. 4.3-5.5 mm. wide, ciliate-pubescent along the mar- 

 gins of the lobes, lateral lobes broad and only slightly spreading, 

 middle lobe blunt triangular ; samara ovate to slightly obovate, 2.5-3 

 mm. wide, nutlet 1.6-1.8 mm. wide, about twice as wide as the wing. 

 (Fig. 1, r-s, fig. 2. m-r.) 



In tamarack swamps, comparatively rare. Only three collec- 

 tions from Hennepin County and one from Anoka County have 

 thus far been seen. (The plant referred to by Schneider and col- 

 lected at Clark's Lake, Michigan, may perhaps be identical with 

 ours.) 



