Crataegus Rosaceae 533 



interdimal flats and on the low and high banks of lakes and streams. This 

 species is the largest of the genus in the state, sometimes reaching a diame- 

 ter of 7 inches and a height of 40 feet. 



Newf., N. E. to Mich., southw. to Ga., Ala., and Kans. 



3345. CRATAEGUS' L. Hawthorn, Thorn, Red Haw 



[Britton and Brown. Illustrated Flora of the Northeastern United 

 States, ed. 2: 294-321. 1913; Palmer. Synopsis of North American 

 Crataegi. Jour. Arnold Arboretum 6: 5-128. 1925; Palmer. The Crataegus 

 problem. Jour. Arnold Arboretum 13: 342-362. 1932; and Deam. Trees 

 of Indiana, ed. 2: 192-228. 1932.] 



Shrubs or small trees, usually found in pastures, thickets, and borders 

 of woodland, and most abundantly in limestone regions. Many of the 

 species are attractive on account of their flowers, foliage, and fruit, and 

 are frequently planted in parks and private grounds. The fruit of some 

 species is edible and is sometimes sold on the market in some sections, 

 where it is eaten raw or used for preserves ; its chief value in Indiana is 

 for bird and game food. 



Crataegus is one of the largest genera of woody plants in the number of 

 species, and it is one of the most difficult for taxonomic treatment. Several 

 hundred American species and varieties have been proposed, many of 

 which are probably hybrids or only forms of polymorphic species. In many 

 cases it is difficult to find a single constant character that can be relied 

 upon for separating species, even though they seem to be distinct when 

 all of the characters are considered. The dimensions of leaves, flowers, 

 and fruit given in the descriptions are intended to cover the normal range, 

 but it should be understood that there may be wider variations in unusually 

 vigorous or depauperate forms. 



KEY TO THE GROUPS 



Nutlets not pitted on ventral surfaces; flowers (except in Cordatae) usually opening 

 before the middle of May. 

 Fruiting calyx persistent; fruit usually falling soon after maturity; flowers 12-25 

 mm in diameter. 

 Leaves of flowering branches all narrowed or acuminate at the base, mostly of an 

 obovate, oblong, or spatulate type, broadest at or above the middle, margins 

 merely serrate or with shallow or obscure lobes toward the apex. 

 Leaves of flowering branches usually one and a half to twice as long as wide 

 (forms of group IV may be sought here). 

 Leaves thick and usually glossy above, unlobed except rarely on shoots; veins 

 not conspicuously impressed; styles and nutlets 1-3 (rarely more); fruit 



remaining hard and dry I. Crus-galli. 



Leaves thin to firm, dull above, often slightly lobed on flowering branches; 



styles and nutlets 2-5; fruit becoming mellow. 



Leaves of flowering branches mostly obovate, symmetrical, with 5-7 pairs 



of slightly ascending, deeply impressed veins; fruit 9-16 mm in 



diameter (rarely larger) ; nutlets usually 2-4 II. Punctatae. 



1 The text of the genus Crataegus was written by Ernest J. Palmer of the Arnold 

 Arboretum, Harvard University. The manuscript has, with his approval, been made 

 to conform to the general style of the book. 



