102 Rhodora [JUNE 
888 (distributed under a manuscript varietal name which, happily, 
does not appear to have been published). 
Var. LEIOCARPUM, DC. Sparingly pubescent with stiffish slightly 
retrorse hairs; the inflorescence nearly smooth; pods entirely gla- 
brous or with a few scattered hairs: plant inclining to yellowish 
green.— Syst. ii. 460 (1821) ; Guss. Fl. Sic. ii. 188 (1843) ; Fournier, 
Fam. des Crucif. 85 (1865); Rouy & Foucaud, Fl. Fr. ii. 20 (1895). 
S. leiocarpum, Jord. Diag. 139 (1864). S. officinale of nearly all 
American authors. Ærysimum officinale, Pursh, Fl. Bor. Am. ii. 436 
(1814). — Very common in North America (the original specimen 
from South Carolina). In the Old World rather rare, reported as 
follows : — Teneriffe according to DC. 1. c. ; Sicily, according to Guss. 
l. c. (an occurrence further proved by Todaro’s no. 829 from 
Palermo); here and there in various parts of France and Corsica, 
according to Rouy & Foucaud, l. c. 
These two forms of Sisymbrium officinale furnish an interesting 
parallel with Chrysanthemum Leucanthemum and its variety subpin- 
natifidum, described by Mr. Fernald  (RHODORA, v. 181), and with 
Lactuca Scariola and its variety integrata, recently discussed by Mr. 
L. H. Dewey (RhHobora, vii. 9-12). In each instance the typical 
form of the species (by which 1 mean here only that form which was 
first characterized) is a plant widely distributed and abundant in the 
Old World, but rare, local, and probably of rather recent introduc- 
tion in America, while the varieties, although relatively rare in the 
Old World have taken a firm hold in America and are now widely 
distributed on this continent as pernicious weeds. 
It is evident that the typical form of Sisymbrium officinale in its 
American occurrence is as yet chiefly established in California, where 
the variety, so common in other parts of the United States, appears 
to be rather rare. 
The variety Zezecarpum is so readily distinguished that there will 
be a temptation on the part of many to consider it distinct, as did 
Jordan. But it has been impossible as yet to correlate with the 
difference of pubescence any other clear or constant distinction. 
There is, it is true, a general tendency in the smoother form to have 
more slender pods and a slightly longer style. These differences, 
however, are by no means constant and the other distinctions of 
leaf-contour, length of seed, etc., mentioned by Jordan, are quite as 
often reversed as true in the sense in which he applied them. 
