18. Cruciferae 75 



6. Leaves, at least the median and lower, auriculatc; at base; 

 mature pods less than 2 mm wide. 



7. Mature pods 2-2.5 cm long, straight, spreading; seeds wing- 

 less; petals white or pale lavender, 2-3 mm long; stem- 

 leaves oblanceolate, obtusish, unequally dentate; moist 

 woods near streams, common. Apr.-June. [^4. dentata 

 T. & G., homonym] A. shortii (Fern.) Gleason 



7. Mature pods 4-9 cm long, arcuate-recurved; seeds winged; 

 petals greenish-white, 4-6 mm long; plant glabrous 

 throughout; gravelly soil in woods. Apr.-June. Smooth 

 Rockcress A. laevigata (Muhl.) Poir. 



20. Arabidopsis Heynh. — Mouse-ear Cress 



A. thaliana (L.) Heynh. Waste places, chiefly in the s. counties; 

 nat. from Eur. Apr.-June. 



21. Nasturtium R.Br. — Watercress 

 A'^. officinale R.Br. In clear water, especially in or near springs; 

 nat. from Eurasia. May-Sept. 



22. Neobeckia Greene 

 A^. aquatica (A. Eaton) Greene. Ditches, ponds, or slow streams, 

 not common. June-Aug. [Arrnoracia aquatica (A. Eaton) Wieg.]. 



23. Armoracia Gaertn. — Horseradish 



A. rustic ana (Lam.) Gaertn. Waste places, ditches, roadsides; 

 escaped from cult.; native of Eur. May-June. [A. lapathifolia Gilib., 

 nom. invalid.] 



24. Alyssum L. 



A. alyssoides L. Fields and waste places, occasional: nat. from 

 Eur. May-June. 



25. Lobularia Desv. Sweet Alyssum 



L. maritima (L.) Desv. Occasionally spontaneous after cult.; 

 introd. from Eur. 



26. Berteroa DC. — Hoary Alyssimi 



B. incana (L. ) DC. Waste places, locally abimdant; nat. from 

 Eur. June-Sept. 



27. Lesquerella Wats. — Bladder-pod 

 1. Pods, as well as the whole plant, densely stellate-pubescent; plants 

 perennial; in sand or sandy soil, rare; Havana, Mason Co., 

 Aug. 22, 1904, H. A. Gleason [L. argentea (Pursh) MacM., 



non (Schauer) Wats.] L. ludoviciana (Nutt.) W^ats. 



1. Pods glabrous; plants annual, sparsely stellate- pubescent ; "by the 

 Chicago & Alton R.R. near Rock Bridge, s. of Willow Springs, 

 June 9, 1894," Hill; east of Sag Bridge, June 9, 1894, Mofjatt 

 172 ("only two plants found; fruit immature.") ; native in Okla. 

 and Tex. [L. nuttallii Wats.] L. gracilis (Hook.) Wats. 



