30 CRUCirERuE. (MUSTARD FAMILY.) 



1. NASTURTIUM, R. Br. WATER-CRESS. 



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

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

 raarginless, in 2 irregular rows in each cell. Cotyledons accumbcnt. 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 effect of its pungent qualities.) 



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



1. ! OFFICINALE, R. Br. (WATER-GUESS.) Stems spreading and root- 

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

 slender widely spreading pedicels. 1J. Brooks and ditches; rare: escaped 

 from cultivation. (Nat. from Eu.) 



$ 2. Petals yellow or yelloivish, seldom much exceeding the calyx : pods linear, oblong, 

 ovoid, or globular : leaves mostly pinnatijid. 



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



2. N. SYLVESTRE. R. Br. (YELLOW CRESS.) Stems ascending; leaves 

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

 (4"_6" long), on slender pedicels; style very short. Wet meadows, near Phila- 

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



3. N. Simmtllin, Nutt. Stems low, diffuse; leaves pinnatcly cleft, the 

 short lobes nearly entire, 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 : Jlowers small 



or minute, greenish or yellowish : leaves somewhat lyrate. 



4. N. SCSSiliflorilin, Nutt. Stems erect, rather simple ; leaves obtusely 

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

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

 ward. April - June. 



5. N. Ol>t JiSlim, Nutt. Stems much branched, diffusely spreading ; 

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

 repand ; Jloicers minute, short-pedicelled ; pods longer than the pedicels, varying 

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



6. Nt pal Astro, DC. (MARSH CRESS.) Stem erect; Imies pinnatdy 

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

 al)out as long as the small Jlowers and mostly longer than the oblong, ellipsoid, or 

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

 -Sept. Flowers only l"-l" long. Stems l-3 high. The typical form 

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

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

 with ovoid or globular pods. (Eu.) 



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

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



7. N. lacustre, Gray, Gen. 111. 1, p. 132. (LAKE CRESS.) Aquatic, 

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

 emersed leaves oblong, entire, serrate, or piunatifid ; pedicels widely spreading ; 



