No. 484] 



CLOSELY RELATED SPECIES 



229 



To Professor Charles Sprague Sargent I am indebted for inter- 

 esting information as to the distribution of North American 

 Crataegus. As is well known, numerous species have bc<'n (hs- 

 tinguished within the last few years, of which sonic five Inmdrcd 

 have been named. These species are readily and unniistakahlv 

 recognized by special students of the genus, by means of Horal 

 characters such as number of stamens, color of anthers, form of 

 inflorescence, etc.; by fruit characters, configuration of nutlet, 

 time of blooming and fruiting, character of foliage, veining, pres- 

 ence or absence of hairs, etc.; traits which appear to be constant 

 and reliable as shown by extended observation in the field and 

 by cultures of seedlings carried on now for a number of years at 

 the Arnold Arboretum. In these cultures, the sowings from the 

 several species result in crops of seedlings of remarkable uni- 

 formity within the limits of each species, and in the instances in 

 which the seedlings have flowered and fruited, of notable con- 

 formity to parental type. This result must certainly diminish 

 the scepticism with which the proposal of such a vast number of 

 species within the one genus has rather naturally been met in some 

 quarters. 



In answer to the question whether the ncanv-r n lated species 

 are separated, as the law of 1). S, Jonhin and of Wagner w^ould 

 require. Professor Sargent re|)li('s in the m-uative. 



In the genus as it is represented in North America several 

 groups are distinguished, which hi part (•()rresj)<)nd to the spec-ies 

 of the older writers, and whicii may lie reathly recognized by 

 anyone with a little attention- such are Crns-oalh, Punctata-, 

 iEstivales, Tenuifolite, Pruinosae, Intri( ata', llaht hata", Anoinahe, 

 Molles, Tomentosse, etc. These groups arc in p'neral fairly 

 well restricted to particular geograpliic x'ction^. For e.\anij)le, 

 the Tenuifolia^ the largest group in the northeast, do not cxtt'iid 

 west of tlie Mississippi river, or go southwani except alonu' tlie 

 mountains. The Flava^ are found only in the ^onthca^t. The 



along the mountains southward to the end of the Alle-rhanies, 

 northward into Vermont, and westward through New ^'ork and 

 Ontario to southern Michigan, within which distributional area they 

 mingle with all the other northern groups. In some cases a group 



