Jan., 1902.] Botanical Correspondence. 189- 



The full title is as follows : Manual of the Flora of the 

 Northern States and Canada, by Nathaniel Lord Britton, Ph. D. 

 The author is the director-in-chief of the New York Botanical 

 Garden and Emeritus Professor of Botany in Columbia Univer- 

 sity. . The publishers are Henry Holt & Co., New York, and the 

 price is $2.25. 



/fern <?. A beginner asks, ', what a double citation of authors 

 signifies " ; he wishes to know also the reason for occasional 

 " duplication of a generic name " for the species. Examples of 

 the two cases, taken at random, are as follows : 



1. Grape Fern ; Botrychium virginianum (L.j Sw. 



2. Marsh Muhlenbergia; Muhlenbergia racemo.sa (Mx.) B. S. P. 



3. Kentucky coffee tree ; Gymnocladus dioicus (E.) Koch. 



4. Upland white Aster; Aster ptarmicoides lutescens (Hook.) 

 Gr. 



5. Indian mallow ; Abutilon abutilon (E.) Rusby. 



6. Dandelion; Taraxacum taraxacum (E.) Karst. 



In brief explanation of the above the following may be stated: 



1. Einnaeus named this plant Osmiuida virginiana, but it is 

 not an Osmunda as that genus is now understood, and Swartz 

 placed it in the genus Botrychium. 



2. Muhlenberg placed this grass in the genus Agrostis, with 

 the name Agrostis racemosa, and it was afterwards changed to 

 its proper place by Britton, Stearns and Poggendorf. 



3. The Kentucky coffee tree was first given a botanical name 

 in 1753 by Einnaeus ; then when the genus Gymnocladus was 

 proposed the plant was rechristened Gymnocladus canadensis (a 

 name used in Gray's Manual) by Eamarck in the year 17S3 ; the 

 first specific name was restored — according to the rule of priority 

 now generally recognized by naturalists — by Koch in 1S69. 



4. This variet}' of aster was named by Hooker as Diplopappus 

 albus var. lutescens ; then Torrey and Gray placed it in the 

 genus Aster with the specific nume A. lutescens, and Gray sub- 

 sequently published it as Aster ptarmicoides var. lutescens, hence 

 the citation as given in the later publications. 



5. The Indian mallow was first enumerated b}^ Einnaeus as 

 Sida abutilon in 1753, ^^^ ^'^^ Species Plantarum. The genus 

 Abutilon was published by Gaertner in 1791. This plant is an 

 Abutilon as botanists interpret that genus ; it was only lately 

 (1894) that Dr. Rusby restored the original specific name, which 

 is abutilon, but the fact that it is similar in form to the now 

 recognized generic name does not invalidate it in the opinion of 

 most American botanists. 



6. The Dandelion was given in Einnaeus' s Species Plantarum 

 as Eeontodon taraxacum, 1753; then Weber named the plant 

 Taraxacum officinale, 1780 ; later Desfontaines called it Taraxa- 

 cum dens-leonis, 1800 ; it was Karsten, 1883, who properly 

 restored the original specific name, this being the same in form as^ 

 the generic name long since recognized by all botanists. 



