I 



and Old World Birches. 193 



EXPLANATION OF PLATES.* 



Plate V, figs. 1-6, Betula alba. 



Figure 1. — Leaf of young flowering branch of B. pubescens, Ehrh., from 

 the Vosges Mts. , near Rambervilles, France (Joad). 



Figure 2. — Leaf of fruiting branch, of B. papyrifera, Marsh., from Lake 

 Winnipeg, Manitoba (Bourgeau). 



Figure 3. — Leaf of fruiting branch of B. occidentalis, Hook., from Pend 

 d'Oreille Eiver, British Columbia (Lyall). 



Figure 4. — Leaf of young branch of B. pubescens, Ehrh., from Bohemia 

 (Tausch). 



Figure 5. — Leaf of fruiting branch of B. papyrifera, Marsh., from South- 

 port, Maine (Fernald). 



Figure 6. — Leaf of fruiting branch from Austria — after Ettingshausen and 

 Pokorny, Phys. PI. Aust. iii, t. 201. 



Plate V, figs. 7 to 12, B. alba, var. minor. 



Figure 7. — Leaf of fruiting branch of B. tortuosa, Ledeb., from the Altai 



Mts., Siberia (ex. herb. St. Petersb.). 

 Figure 8. — Leaf of fruiting branch of B. odorata, var. tortuosa, Lange, 



from the Dovre Mts., Norway — after Lange, Fl. Dan. xvii, t. 2918. 

 Figures 9, 10. — Leaves of original fruiting branches of B. papyracea, var. 



minor. Tuck., from Mt. Washington, New Hampshire. 

 Figure 11. — Leaf of dwarf form of B. papyracea, var. minor, Tuck., from 



Mt. Washington, New Hampshire iFaxo7i). 

 Figure 12. — Leaf of fruiting branch of B. odorata, var. minor, Rosenvinge 



in herb., from Greenland (Hartz). 



Plate V, figs. 13, 14, B. alba var. carpatica. 



Figure 13. — Leaf of fruiting branch of B. borealis, Spach, from Anticosti, 



Quebec (Macoun). 

 Figure 14. — Leaf of B. alba, subsp. pubescens, C carpatica, Regel, from 



Lapland (Regel). 



Plate V, figs. 15 to 18, Plate YI, figs. 19 to 22, B. pendula. 



Figures 15, 17. — Leaves of young flowering branch of B. alba, subsp. ver- 

 rucosa, S resin?/e7'a, Regel (type of B. alaskana, Sargent) from 

 Saskatchewan (Bourgeau). 



Figures 16, 18. — Leaves of fruiting branch of B. verrucosa, Ehrh., from 

 Christiania, Norway (Blytt). 



Figure 19. — Leaf of fruiting branch of B. pendula, from Warren, Illinois 

 {L. M. Umbach, sheet No. 351,017 U. S. Nat. Herb.). 



Figure 20. — Leaf of fruiting branch from Gotland, Sweden (Blomberg). 



Figure 21. — Leaf of B. alba, subsp. mandshurica, Regel, from Mandschuria — 

 after the original illustration (Regel, Bull. Soc. Imp. Nat. Mosc, 

 1865, t. 7, fig. 15). 



Figure 22. — Leaf of fruiting branch of B. verrucosa, 6 resinifera, Regel, 

 from Nushagak River, Yukon District, Alaska (McKay). 



Plate YI, figs. 23, 24, B. pendula, var. japonica. 



Figure 23. — Leaf of B. alba, subsp. latifolia, a Tauschii, Regel, from Eastern 

 Asia— after Regel, Bull. Soc. Imp. Nat. Mosc, 1865, t. 7, fig. 11. 



Figure 24. — Leaf of B. kenaica, W. H. Evans, from Cook Inlet, Alaska 

 (Coville and Kearney, No. 2412). 



*The plates illustrating this paper have beeA carefully prepared by Mr. 

 F. Schuyler Mathews. Unless otherwise stated, the figures are life-sized. 



