134 Rhodora [JuLy 
THE NORTH AMERICAN SPECIES OF BARBAREA. 
M. L. FERNALD. 
A recent attempt to determine satisfactorily some specimens of 
Barbarea from different regions of North America has led the writer 
to make a somewhat detailed study of the genus. In the course of 
this study it has become apparent that the species, which are notori- 
ously difficult of delimitation, have more definite characters of foliage 
and fruit than we have generally supposed, and that in some cases our 
interpretation must be changed by a more accurate knowledge of 
certain of the older species. In the interpretation of the European 
species the writer has gained much assistance from the treatment of 
the genus and the critical notes of Rouy & Foucaud ! and the earlier 
observations of Des Moulins.” 
As commonly interpreted, Barbarea in America consists of B. vulgaris 
R. Br. (including arcuata) with divergent or arcuate-ascending pods, 
introduced eastward but said to be indigenous from Lake Superior 
northward and westward; B. stricta Andrz., with closely appressed 
pods, occurring across boreal America and coming south to Virginia, 
the Great Lake region, Missouri, and along the Rocky Mts.; and 
B. verna (Mill.) Asch. (B. praecox Sm.), an introduced garden-plant. 
Recently, however, Dr. Rydberg has characterized the plant of the 
Rocky Mts. as B. americana. 
Ап inspection of all the American material in the Gray Herbarium 
and the herbarium of the New England Botanical Club shows that our 
Barbareas fall into two rather clearly marked groups. Тһе first group 
consists of plants which are represented in these collections only by 
specimens from the older settled portions of America (chiefly in the 
East) and which, although now naturalized, were probably introduced 
from Europe. In all these plants the beak of the silique, formed by 
the persistent style, is very slender and elongate (2-3 mm. long) and 
the uppermost leaves of the stem are coarsely dentate, angulate, or 
lobed, but very rarely pinnatifid. ‘These plants include the introduced 
Barbarea vulgaris; another probably introduced plant which has been 
passing in the Eastern States as B. stricta; and a singular short- 
1 Fl. de France, i, 196-203 (1893). 
? Catalogue raisonné des Phanérogames de le Dordogne, 2e, fasc, du Suppl., 20-54 
(1849). ы 
