CRUCIFERAE. 



i. Thlaspi arvense L. Field Penny- 

 cress. French weed. Fig. 2045. 



Thalspi arvense L. Sp. PI. 646. 1753. 



Annual, erect, glabrous, 6'-i8' high, sim- 

 ple or branching above. Basal leaves petioled, 

 oblanceolate, early deciduous; stem-leaves 

 oblong or lanceolate, sparingly dentate, the 

 upper clasping the stem by an auricled base, 

 the lower merely sessile; flowers white, about 

 i" long, \" broad; pedicels spreading or 

 curved upward, slender, 5"-9" long in fruit; 

 pods nearly orbicular when ripe, 4' -6" broad, 

 very flat, broadly winged all around, notched 

 at the apex, in long racemes ; style minute, or 

 none ; seeds rugose, about 6 in each cell. 



In waste places and on ballast, Quebec to New 

 York, Manitoba and Kansas. Naturalized from 

 Europe. Native also of Asia. June Aug. Bas- 

 tard cress. Dish-mustard. Treacle-wort. 



2. Thlaspi perfoliatum L. Per foliate 



Penny-cress. Fig. 2046. 

 Thlaspi perfoliatum L. Sp. PL 646. 1753. 



Annual, glabrous, branched at the base, stems 

 commonly simple, slender, ascending or erect, 

 3'-7' tall. Basal leaves ovate or suborbicular, 

 often petioled; stem-leaves oblong or oblong- 

 lanceolate, sessile, auricled at the base and 

 clasping the stem, i'-i' long, 3"-6" wide, 

 obtuse or acute at the apex; pedicels filiform, 

 spreading; silicic obovate-orbicular, 2"-3" 

 broad, rather narrowly winged, broadly 

 notched at the summit; style short but mani- 

 fest; seeds usually 4 in each cell. 



Hamilton, Ontario, and Geneva, New York. 

 Advcntive from Europe. May-Aug. 



20. MYAGRUM L. Sp. PI. 640. 1753. 

 An annual glabrous glaucous branching herb, 



with entire or undulate oblong to lanceolate 



leaves, the lower petioled, the upper sessile and deeply auricled at the base. Flowers small, 



yellow, in elongating racemes ; pedicels short, erect-ascending, bractless. Sepals nearly erect. 



Petals short ; longer stamens somewhat connate in pairs 

 Silicic obcuneate to spatulate, flattened, indehiscent, 

 falsely 3-celled, i-seeded, tipped by the short style. Seed 

 pendulous; cotyledons incumbent. [Greek, a fly-trap.] 



A monotypic genus of Europe and western Asia. 



i. Myagrum perfoliatum L. Myagrum. 

 Fig. 2047. 



Myagrum perfoliatum L. Sp. PL 640. 1753. 



Lower leaves oblong, narrowed into petioles ; upper 

 leaves 2'-$' long, i'-i' wide, obtuse or acutish at the 

 apex, the basal auricles mostly rounded; racemes, in 

 fruit, elongating to several inches in length ; pedicels 

 i "-2" long, 2-3 times shorter than the pods, equalling 

 or a little longer than the calyx ; longer stamens about 

 equalling the petals. 



In waste places about Quebec. Fugitive or adventive 

 from Europe. Summer. 



