PRUNUS RIVULARIS 207 



a form of Prunus Americana." The whole group has also been 

 roughly referred to P. glandulosa, Torr. & Gray, but this is evi- 

 dently a mistake. Mr. T. V. Munson has given this question 

 serious study, and has concluded that all these varieties are 

 derived from P. rivularis, Scheele. This is a somewhat start- 

 ling decision, and extremely important if true. The facts are, 

 however, first, that we are yet too poorly acquainted with this 

 species to make critical comparisons ; secondly, that Scheele's 

 description, made at second hand from Lindheimer's speci- 

 mens, is not sufficiently precise to preclude mistakes ; thirdly, 

 that the description,* what there is of it, fails, in important 

 particulars, to fit the varieties in question ; and fourthly, that 

 many of these varieties have originated in localities where it 

 is almost impossible to believe that P. rivularis could be grow- 

 ing. (See pages 223, 224.) 



To particularize further, the National Herbarium f contains 

 only the following specimens : Those of Lindheimer, collected 

 in western Texas in 1846 ; one by Hall, from Dallas ; two by 

 Wolf, collected in Illinois in 1875, and very possibly cultivated 

 specimens ; and one of doubtful authenticity, by Thomas Bass- 

 ler, from Manhattan, Kansas. Other herbaria seem to have 

 no better representation of the species, and this could hardly 

 be the case were it so common and so widely distributed as to 

 furnish the well-known cultivated varieties mentioned above. 



*Sinee this description is inaccessible to many students, it will be well to 

 transcribe it here : 



Prunus rivularis, Scheele, Linncea, xxi., 594. Frutex 3-6 pedalis; rami angu- 

 lati glabri nitidi cinerei verruculosi, verrucae parvae coiifertse. Petioli glandulosi 

 canaliculati puberuli. Folia ovate-oblonga acuuiinata insequaliter serrulata, basi 

 glandulosa, subtus sporeae pubescentia, supra glabra, serraturw callosae confertae. 

 Umbellse laterales sessiles subbiflor*. Squamae gemmae floriferae aphylla?. Pe- 

 dunculi glabri elongati subglandulosi, petiolum aequantes. Flores . . . Drupa 

 rubra globosa glabra nitida acida. 



"Gesellschaftlich an Bachrandern, selltener aber jedesmal in Menge zusam- 

 menstehenden auf Hugeln. Strauch 3-6' hoch, Frucht kugelig, hell-roth, ange- 

 nehm sauerlich, von der Grosse eiuer Kirsche biszu der einer Mirabelle. %-i" 

 diek. Die Tawakong-Indianer sollen die Frucht, mit honig gekocht, sehr lieben. 

 Die Texaner nennen sie 'Tawakong plum.' "Lindheimer. 

 Gehort zur Rotte Eucerasus, Torr. & Gray. 

 Seltener stehen die Blnmen einzeln. 



tThe specimens in the National Herbarium were kindly examined for me by 

 Mr. Lyster H. Dewey. 



