GERMINATION OF TREES AND SHRUBS 



317 



leaf thin, pubescent on veins and margins, dentate. Trichomes 

 straight or eur\'ed, one-celled, pointed, slightly enlarged at base ; 

 cell wall thin, colorless. Seeds germinated freely out of doors 

 by :\ray 25. 



Celtis occidentalis L. Germination epiggeous, root dirty white, 

 long, tapering; lower part of stem purplish; upper portion 



Fig". 7S 



Fit 



Fi£ 



Fig. 7S. — Germinating slippery elm ( Ulmiis fulva), sessile cotyledons, 

 coarsely toothed petioled leaves. Pliotogiaphed by Photo. Section, F. E. Col- 

 liurn. 



Fig. 



leaves. 



79. — Chinese elm (Ulinus puniila), stalked cotyledons, coarsely toothed 

 Photographed by Photo. Section, F. E. Colburn. 



Fig. 80. — Seedlings of Celtis occidentalis from La Crosse, Wisconsin, show- 

 ? cotyledons. Photographed by Photo. Section, F. E. Colburn. 



roughened, but not pubescent; cotyledons short stalked, smooth, 

 oljcordate, deeply cut at apex in two lobes, obscurely 3-5 nerved, 

 smooth above and bielow ; buds in axils of cotyledons, stem abiove 

 cotyledons pubescent. Leaf penninerved, reticulately veined, 

 margin coarsely dentate. Base of leaf unequaJ, veins quite pub- 

 escent. Third leaf alternate, stem pubescent. Upper surface of 

 leaf rugose pubescent, and lower surface reticulately veined, in 

 older plants .spreading fan-shaped. Lubbock'" describes the 

 seedlings of Celtis occidentalis. Trichomes of two types, longer 

 ones simple, slender, acutely pointed, roughened longitudinally, 



'"A contribution to our knowledge of seedlings, ;?, pp. 494-495. 



