68 BIcKNELL : FERNS AND FLOWERING PLANTS OF NANTUCKET 
BARBAREA RIVULARIS Martr. Pl. Crit. du Tarn. 1: 9. 1862; FI. 
Tarn. 44. 1864. . 
Barbarea stricta auct. Am. Not Andrz. 
A plant of comparatively recent introduction to Nantucket 
and now fast becoming widely established. Mrs. Owen reports 
Barbarea vulgaris as having first appeared in 1883; this record 
probably refers to the species here discussed, which was not at 
that time generally recognized as distinct from B. vulgaris, In 
September, 1889, I observed two plants in a weedy alley in the 
town, but saw nothing more of it until June, 1908, when a few 
plants were observed near the old wharves and by a street-side in 
the town and a mass of it occupied a shallow gully in the side of 
the cliff. The next year it had spread extensively and was seen 
at a number of points in the town as well as in fields near by, and 
at such distant points as Miacomet Pond farm, Hummock Pond 
and the life-saving station at the southwestern side of the island. 
In full flower May 30, 1909. 
* RapiIcULA NASTURTIUM-AQUATICUM (L.) Britten & Rendle. 
Growing in luxuriant masses about springs and ditches at 
Shawaukemmo ; Watt’s Run; near Reed Pond. First flowers 
May 30, 1909. 
* RADICULA PALUSTRIS (L.) Moench. 
A group of half a dozen plants just in flower June 6, 1909, at 
edge of pool by the Madequet road, just beyond Crooked Lane. 
* Rapicuta ArmoraciA (L.) Robinson. 
Frequent in and near the town; ditch in Polpis. Just in 
flower May 30, 1909. 
CARDAMINE PENNSYLVANICA Muhl. 
Not common; ditches west and southwest of the town; 
Quaise ; Polpis ; Watt’s Run. In full flower May 31, 1909. 
Along Watt’s Run, in the shade of a dense thicket, occurs a 
lax and slender form which so closely simulates Cardamine flexu- 
osa With. that it required a close examination of the siliques and 
styles to convince me that it was not that species. 
* CARDAMINE ARENICOLA Britton. 
Wet meadow west of the town ; Shawkemo ; muddy border of 
sink-hole near Tristram Coffin’s Homestead. In full flower May 
31, 1909. 
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