46b. Stem-leaves sessile or petioled, not clasping, or none --49. 47a. Stem and leaves glabrous or pubescent; pod very flat and circular, about 10 mm. wide (1-5 dm. tall; early summer) =Penny Cress, Thlaspi arvense.= 47b. Stem and leaves glabrous or pubescent; pod not more than 5 mm. wide (1-6 dm. high; spring and early summer) --48. 48a. Pods broadly ovate =Field Cress, Lepidium campestre.= 48b. Pods triangular, or slightly indented at the apex =Shepherd's Purse, Capsella bursa-pastoris.= 49a. Pods about circular, or a very little longer than broad --50. 49b. Pods ovoid or oblong, broadest near the middle, and distinctly longer than wide (Whitlow Grass) --53. 50a. Leaves entire (1-3 dm. high; flowers in summer) =Yellow Alyssum, Alyssum alyssoides.= 50b. Leaves serrate (2-6 dm. high; flowers in summer) --51. 51a. Stamens 6 =Garden Cress, Lepidium sativum.= 51b. Stamens 2 (Pepper Grass) --52. 52a. Petals present =Pepper Grass, Lepidium virginicum.= 52b. Petals none =Pepper Grass, Lepidium apetalum.= 53a. Petals deeply 2-cleft (about 1 dm. high; early spring) =Whitlow Grass, Draba verna.= 53b. Petals entire or barely notched at the tip --54. 54a. Leaves all or chiefly at or near the base (about 1 dm. high; spring) =Whitlow Grass, Draba caroliniana.= 54b. Stems leafy up to the flowers (1-5 dm. high; summer) =Whitlow Grass, Draba arabisans.= 55a. Stem-leaves cordate or sagittate at the base and sessile, forming a more or less clasping leaf (3-10 dm. high) (Rock Cress) --56. 55b. Stem-leaves sessile or somewhat petioled, but not clasping --63. 56a. Seeds in 2 rows in each cavity of the pod (early summer) --57. 56b. Seeds in 1 row in each cavity of the pod --59. 57a. Calyx pubescent; the pods reflexed =Rock Cress, Arabis holboellii.= 57b. Calyx glabrous; the pods spreading or ascending --58. 58a. Basal leaves densely pubescent =Rock Cress, Arabis brachycarpa.= 58b. Basal leaves smooth or nearly so =Rock Cress, Arabis drummondii.= 59a. Petals conspicuous, about twice as long as the calyx, or longer; straight, erect, mostly unbranched plants --60. 59b. Petals inconspicuous, equaling or but little longer than the calyx --61. 60a. Pods 3-4 cm. long, ascending (summer) =Rock Cress, Arabis patens.= 60b. Pods 8-10 cm. long, recurved (late spring) =Rock Cress, Arabis laevigata.=