jns 



IOWA ACADEMY OF SCIENCE Vol. XXV. 191S 



at the base, margiu A\dth coarse serrations, a few scattered hairs 

 on the under surface of the leaf. Midrib prominent, petiole 

 slightly hairy, stipules small, lanceolate, green. Hairs simple, 

 varying in length, oceasionallj'bent above the middle, frequenth- 

 enlarged at the base, cell-walls thin. 



Fig. 60 Fig. 61 



Fig. 63 Fie. 64 Fig. 65 



Fig. 60. — Trichomes of leaf of Corylus americana, sliowing also glandular 

 tip of serration. Drawn by C. M. King. 



Fig. 61. — Ostrya vnrginiana, seedling. Drawn by C. M. King. 



Fig. 62. — Group 1, trichomes of Ostrya virginiana. Group 2. trichomes of 

 Betula papyrifera. .Group 3, gland, from leaf. Drawn by C. M. King. 



Fig. 63. — Betula hitea, seedling. Drawn by C. M. King. 



Fig. 64. — Betula papyrifera, seedling. Drawn by C. M. King. 



Fig. 65 — Betnla alba var. papyrifei'a, showing cotyledons and expanded 

 plumule. Drawn by C. M. King. 



Betula (tJha var. papyrifera (Marsh) Spach. Paper Birrh. 

 Collected at Osage, Iowa, October, 1917, stratified outside, 

 planted in gTeenhouse, March 14, 1918, germinated April 15, 

 1918, a'bout 5 per cent. Germination epigaK)ns. Hypocotyl 

 reddish, slightly pubescent, cotyledons small, about 3 mm. l)y 4 

 mm., granular in a])nearancc; smooth below, with purple coJoi'. 



