85 



known is that contained in the large tamarack swamp near Mineral 

 Springs in Porter County. In this swamp are found tamarack and 

 white cedar. It was in this swamp that the writer found a peculiar 

 form of birch which has been determined as Betula Sandbergi. Since 

 this species 1 is recognized as a hybrid of Betula papyrifera and Betula 

 pumila variety glandulifera, and the last parent of this hybrid is not 

 found in the vicinity, a discussion of this form is not presented. In 

 the immediate vicinity are found only Betula lutea and Betula pumila. 

 Betula papyrifera is found about a mile distant to the south. It is 

 assumed that this form is a cross between Betula lutea and Betula pumila. 



2. Betula populifolia Marshall. GRAY OR WHITE Bmch. Plate 



33. A small tree; bark a chalky white, not separating into thin layers, 

 inner bark orange, on the trunks of old trees nearly black; shoots at 

 first covered with numerous glands, becoming smooth and yellowish 

 or reddish-brown; leaves generally long-deltoid, average blades 3-6 cm. 

 long, usually long taper-pointed, truncate or nearly so at the base, 

 irregularly double-serrate, slightly pubescent on the veins when young, 

 soon becoming glabrous; fertile catkins 1.5-3 cm. long and about 7 

 mm. in diameter; bracts of eastern trees differ from those of Indiana 

 trees which are about 3-4 mm. long, lobed to about 1/3 of the distance 

 from the apex, lateral lobes the largest and strongly divaricate, puber- 

 ulent on the back; seed strongly notched at the apex; nut slightly obo- 

 void; wings much broader than the nut. 



Distribution.- Nova Scotia west to southern Ontario and south to 

 Delaware and Pennsylvania. In Indiana it has been reported from 

 Lake, Laporte, Porter, St. Joseph and Tippecanoe Counties. Theie 

 may be some doubt about the Tippecanoe record, since many of the 

 older records were made from cultivated trees. The numbers of the 

 species in Indiana were always limited. It is not able to meet changed 

 conditions and it has already almost disappeared from our area. I 

 was told that formerly this species was found all about a lake in Laporte 

 County, but it has all died out. Its appearance in Indiana is peculiar 

 since it is not found west of us, or north in Michigan or east in Ohio. 

 This small group of trees near Lake Michigan is three or four hundred 

 miles from the nearest of their kind. 



Remarks. This species is called white and gray birch. The 

 largest tree seen in Indiana was about 2 dm. in diameter and 13 m. high. 



3. Betula papyrifera Marshall. PAPER OR CANOE BIRCH. Plate 



34. Rather a small tree ; bark thin, creamy white ; chalky, dark near the 

 base on old trees, separating in thin papery layers; shoots green, glandu- 

 lar and hairy, becoming glabrous and reddish-brown; leaves ovate or 

 rhombic-ovate, acute to long taper-pointed, truncate, rounded or 



iMinnesota Bot. Studies 4:454:1916. 



