1912] Wiegand,— Amelanchier in eastern North America 121 
Incidentally it may be interesting to note here that some relation 
seems to exist between the frequency of crossing and the disturbance of 
natural conditions. Hybrids of both Amelanchier and Rubus seem 
more abundant in places where recent fires or recent clearing of the 
land have disturbed the equilibrium of nature. The frequently dug- 
over railroad embankment is an especially favorable locality for such 
hybrids in Rubus. 
If it is difficult to determine what are species and what are not 
species in the genus Amelanchier, it is no less difficult to determine 
what names should be applied to the species recognized. Synonymy 
here is very extensive and very much involved. It is complicated by 
the faet that many of the species of the earlier authors were un- 
doubtedly aggregates, and also by the fact that several specific names 
were based upon material from European gardens unlike any species 
now known to grow in the wild state. There is also some reason to 
believe that a few names were based upon hybrid specimens. It must 
be understood, therefore, that the nomenclature of the group, even 
after the present attempt to straighten it out, is still in an unsatis- 
factory state. The old types especially, if in existence, must be criti- 
cally studied from the standpoint of the present treatment. A very 
serious attempt has here been made to interpret the older specific 
names; but, when that has seemed impossible, so that the retention 
of the name would demand an arbitrary application, thus creating 
a “permanent source of confusion and error," ! the name has been 
dropped. 
The first name to be considered in connection with Amelanchier 
in eastern North America is the Mespilus canadensis of Linnaeus.? 
The original description is very brief and reads: * MESPILUS inermis, 
foliis ovato-oblongis glabris serratis, caule inermi.— Mespilus inermis, 
foliis subtus glabris obverse-ovatis. Gron. virg. 54. Habitat in 
Virginia, Canada." The reference in Gronovius reads as cited with 
the additional statement: * Frutex Mespilo affinis humilis, non ramosus 
nec aculeatus, foliis alternis subrotundis, eleganter serratis, & ad 
apicem rotundis, . . . .Clayt. n. 60 & 295.” In the Systema Veg. ed. 13 
(p. 388, 1774) Linnaeus says:— “M. inermis, fol. ovato-oblongis 
glabris serratis acutiusculis. Tenera lanata; adultior nuda. Racemi 
1 Internat. Rules Bot. Nom., Art. 51, sect. 4. 
3 Sp. PL, ed. 1, p. 478 (1753). 
