140 TREES AND SHRUBS. 



Malus glaucescens is most nearly related to Mains coronaria, which is readily distinguished by its less distinctly 

 lobed leaves usually rounded at the base and pale yellowish green on their under surface, and by its tomentose shorter 

 and stouter petioles ; the pubescence of the under surface of the leaves disappears usually later in Malus coronaria and is 

 denser and remains longer on the veins and on the petioles, while in Malus glaucescens the pubescence is thinner and 

 more floccose and the leaves quickly become entirely glabrous. The fruit of Malus coronaria ripens later and is sub- 

 globose greenish or greenish yellow ; the cavity at the apex is rather deep and uneven, with separate corrugations, which 

 may even extend into obscure ribs. The specimens from Rochester which I consider represent the type have the calyx 

 coated with a thin floccose caducous tomentum, while the calyx of the specimens from Pennsylvania and North Carolina 

 is quite glabrous. 



Probably to this species belongs a form with densely villous calyx occurring in southwestern Ontario. Of this form 

 I have seen the following specimens, which, however, are so incomplete that it is not possible to place them definitely. 



Woods, Niagara, J. Macoun, May 31, 1901 (ex herb. Geol. Survey, Canada, No. 34,405); Wallaceburgh, J. Macoun, 

 June 17, 1901 (ex herb. Geol. Survey, Canada, No. 34,486) ; Amesburgh, J. Macoun, June 10, 1892 (Fl. Can. No. 

 81) ; Fort Detroit, W. lioott, May 23, 1869 (all in herb. Gray). Here also belongs probably a cultivated plant 

 from Fairmount Park, Philadelphia, A. MacMwee (Nob. 2166, 2166 A in herb. Acad. Nat. Sci. Phila.), May 6 and 

 15, 1901. 



Alfred Rehdek. 



EXPLANATION OF THE PLATE. 

 Plate CLVII. Malus c 



1. A flowering branch, natural size. 



2. Vertical section of a flower, the petals r 



3. A fruiting branch, natural size. 



4. Cross section of a fruit, natural size. 



