30 CEtrciTEEJJ. (mustabd family.) 



1. NASTIITKTIITM, K.Br. Watek-Ckess. 



Pod a short silique or a Bilicle, varying from oblong-linear to globular, terete 

 or nearly so, often curved upwards : valves nerveless. Seeds small, turgid, 

 marginless, in 2 irregular rows in each cell. Cotyledons accumbent. — Aquat- 

 ic or marsh plants, with yellow or white flowers, and pinnate or pinnatifid 

 leaves, usually glabrous. (Name from Nasus tortus, a convulsed nose, alluding 

 to the eflFect of its pungent qualities.) 



§ 1 . Petals white, twice the length of the calyx : pods linear : leaves pinnate. 



1. N. OFFiciNitE, R. Br. (Water-Cress.) Stems spreading and root- 

 ing; leaflets 3-11, roundish or oblong, nearly entire; pods (6" -8" long) on 

 slender widely spreading pedicels. IJ. — Brooks and ditches; rare: escaped 

 from cultivation. (Nat. from Eu.) 



§ 2. Petals yellow or yellowish, seldom much exceeding the calyx : pods linear, oblong, 

 ovoid, or globular : leaves mostly pinnatifid. 



* Perennial from creeping or subterranean shoots: flowers rather large, bright yellow, 



2. N. srLvi:STKE. E. Br. (Yellow Cress.) Stems ascending; leaves 

 pinnately parted, the divisions toothed or cut, lanceolate or linear; pods linear 

 (4"-6" long), on slender pedicels; style very short. — "Wet meadows, nearPliila- 

 delphia ; and Newton, Massachusetts, C. J. Sprague. (Adv. from Eu.) 



3. Hf. Simiatum, Nutt. Stems low, diffuse ; leaves pinnately cleft, the 

 short lobes nearly enth-e, linear-oblong ; pods linear-oblong (4" - 6" long), on 

 slender pedicels ; style slender. — Banks of the Mississippi and westward. June. 



* * Annual or biennial, rarely perennial ? with simple fibrous roots : flowers small 



or mirntte, greenish or yellowish : leaves somewhat lyrate. 



4. IV. sessiliflOj'llIll, Nutt. Stems erect, rather simple ; leaves obtusely 

 incised or toothed, obovate or oblong ; flowers minute, nearly sessile ; pods elon- 

 gated-oblong (5" -6" long), thick ;jtyle very short. — With No. 3 and south- 

 ward. April - June. 



5. Bf. olbtnsnin, Nutt. Stems much branched, diffusely spreading ; 

 leaves pinnately parted or divided, the divisions roundish and obtusely toothed or 

 repand ; flowers minute, short-pedicdled ; pods longer than the pedicels, varying 

 from linear-oblong to short-oval; style short. — With No. 3 and 4. 



6. N. palustre, DC (Marsh Cress.) Stem erect; leaves pinnately 

 cleft or parted, or the upper laciniate ; the lobes oblong, cut-toothed ; pedicels 

 aiout as long as the small flowers and mostly longer than the oblong, ellipsoid, or 

 ovoid pods ; style short. — Wet ditches and borders of streams, common. June 

 - Sept. — Flowers only 1 " - 1 J" long. Stems 1 o - 3° liigh. — The typical form 

 with oblong pods is rare (W. New York, Dr. Sartwell). Short pods and hirsute 

 stems and leaves are common. Var. hispIdum (N. hispidum, DC.) is this, 

 with ovoid or globular pods. (Eu.) 



§ 3. Petals white, much longer than the calyx : pods ovoid or globular : leaves undi- 

 vided, or the lower ones pinnatifid. (Armoracia.) 



7. TV. lacustre, Gray, Gen. 111. 1, p. 132. (Lake Cress.) Aquatic; 

 immersed leaves 1 - 3-piunately dissected into numerous capillary divisions ; 

 cmersed leaves oblong, entire, seiTate, or pinnatifid ; pedicels widely spreading ; 



