12 Rhodora [JANUARY 
almost inaccessible margins of marl- or mud-ponds or in cold bogs 
occurs an unquestionably indigenous plant with milk-white petals. 
‘This is the plant which throughout most of British America and the 
northern States is passing as Cardamine pratensis. This indigenous 
plant with. white petals occurs in the habitats above described or on 
cold springy spots from Ungava to the mouth of the Mackenzie, 
south, chiefly in calcareous regions, to Newfoundland, Anticosti 
Island, the Gaspé Peninsula, Berkshire Co., Massachusetts, perhaps 
northwestern Connecticut, northern New Jersey, central and western 
New York, northern Ohio, northern Indiana, Minnesota and northern 
British Columbia; and it is noteworthy that the keen observer, Pro- 
fessor John Macoun, should have appended to the list of stations 
in his Catalogue of Canadian Plants the comment: “The Canadian 
form is usually more slender than the European, and always white 
flowered.””) 
Color of petals alone is usually a very unsafe character, but in 
this case it is certainly significant that our indigenous plant should 
so generally have white, while the true Cardamine pratensis of Eurasia, 
the plant recently introduced into the Northeast and selecting drier 
habitats than the native, has pink petals. Typical C. pratensis as 
generally defined by European authors has the leaflets of the basal 
rosette, or at least the terminal leaflets, distinctly crenate or dentate 
with several teeth, while the middle and upper cauline leaves have 
the linear to oblong leaflets not abruptly contracted at base. In our 
white-flowered indigenous plant, on the other hand, the leaflets of 
the rosette-leaves are most commonly entire, although they may 
occasionally be shallowly toothed, while the lateral leaflets of the 
middle and often of the upper cauline are usually oblanceolate to 
elliptic and distinctly contracted to petiolules. In these characters 
our plant entirely agrees with C. pratensis, var. palustris Wimmer & 
Grabowski,? at least as identified by O. E. Schulz in his Monographie 
der Gattung Cardamine. Several European specimens thus identified 
by Schulz are inseparable from our plant and the essential characters 
of the variety as given by Schulz are satisfactory: “folia caulina 
foliola elliptica vel oblonga, + integra, lateralia manifesto 
- . . petiolulata . . . Petala plerumque alba."* The plant 
! Macoun, Cat. Can. Pl. i. 41 (1883). 
? Wimm. & Grab. Fl. Siles. ii. pt. 1, 266 (1829). 
30. F. Schulz, Engler's Bot. Jahrb. xxxii, Heft 4, 533 (1903). 
