234 Karl M. Wiegand and Arthur J. Eames 



b. Seeds orbicular, larger, more or less winged. 

 c. Leaves clasping ; pods 1-2 mm. broad, erect or recurved-spreading. 

 d. Leaves hairy ; seeds nearly wingless ; pods erect. 3. A. hirsuta 



d. Leaves glabrous ; seeds broadly winged ; pods spreading. 



4. A. laevigata 

 c. Leaves tapering to a sessile base, pubescent ; pods 2.5-4 mm. broad, falcate, 

 pendent. 5. A. canadensis 



a. Seeds in two rows ; leaves abundant on the stem, clasping, glabrous or the basal 

 rosette with a few minute hairs; plant strict; pods 1.5-2.5 mm. broad, erect. 



6. A. Drummondi 



1. A. lyrata L. Rock Cress. 



Dry shaly banks and sandstone or limestone cliffs, with little or no reference to 

 lime content ; rare. May 20-July 15. 



Caroline, on North Pinnacle (D. !) ; Enfield Glen, rare (D.) ; Fall Creek Gorge, 

 rare (D.) ; "almost wholly wanting on the lake-shore cliffs" (D.). [Also, corner 

 of Seneca Lake; Labrador Lake cliffs, Apulia; and at Jamesville.] 



Ont. to Man. and Alaska, southw. to Conn., Va., Tenn., and B. C. ; rare on the 

 Atlantic Coastal Plain. 



2. A. glabra (L.) Bernh. (A. perfoliata of Cayuga Fl.) Tower Mustard. 



Dry gravelly fields and waste places, with no special reference to lime content of 

 the soil ; scarce. June-July. 



Near Summit Marsh (D.) ; near Headwaters Swamp; roadside above Enfield 

 Falls ; gravel delta between Lick Brook and Buttermilk Creek ; South Hill, above 

 the quarry (D.) ; Ulysses, near Perry (D.) ; Spring Lake and Mud Pond, Conquest. 

 Appearing as though introduced in this flora. 



N. B. to B. C, southw. to n. N. J., Pa., the Great Lakes, S. Dak., Utah, and Calif.; 

 rare or absent on the Atlantic Coastal Plain. Found also in Eu. 



3. A. hirsuta (L.) Scop. 



Dry banks and cliffs in ravines, in calcareous soils; frequent. May 20-June 10. 



Enfield Glen (D. !) ; Six Mile Creek (D. !) ; Cascadilla Creek; Fall Creek 

 (D. !) ; Beebe Lake; Taughannock Gorge; lake shore ravines (D.). 



N. B. to Alaska and B. C, southw. to Ga., Mo., Kans., Ariz., and Calif.; appar- 

 ently not on the Atlantic Coastal Plain. 



4. A. laevigata (Muhl.) Poir. Rock Cress. 



Dry cliffs and banks of the ravines and lake shores, in neutral or calcareous soils ; 

 frequent. May 20-June. 

 In nearly all the ravines of the basin, and on dry banks, in gravelly soil. 

 W. Me. to S. Dak., southw. to Iowa and Ark. ; rare or absent on the Coastal Plain. 



5. A. canadensis L. Sickle-pod. 



Dry cliffs and banks in ravines and on other rocky slopes, in gravelly or stony, 

 neutral or calcareous, soils ; frequent. June-Aug. 



Enfield Glen (£>.!); South Hill (£>.); Six Mile Creek (£>.!); Fall Creek 

 (D. !) ; hillside n. of McKinneys ; n. of Esty Glen; Taughannock Gorge; lake shore 

 ravines (D.) ; "widely distributed, but growing singly" (D.). 



E. Mass., Vt., and Ont., to Minn., southw. to Ga., Tex., and Kans. ; rare or absent 

 on the Coastal Plain. 



6. A. Drummondi Gray. Rock Cress. 



Rocks and shale cliffs, probably in calcareous soils ; frequent. June. 

 In nearly all the ravines of the basin; " especially abundant on the High Cliffs north 

 of King's Ferry" (£>.). 



