Vor. II.] MUSTARD FAMILY. 
1o. Roripa Armoracia (L,.) A. S. Hitchcock. 
Horseradish. (Fig. 1722.) 
Cochlearia Armoracia I,. Sp. Pl. 648. 1753. 
Nasturtium Armoracia Fries; A. Gray, Man. Ed. 2, 31. 
feeds Armoracia A. S. Hitchcock, Spring Fl. Manhat- 
tan, 18. 1894. 
Erect, 2°-3° high, from deep thick roots. Basal 
leaves on thick petioles 6’-12’ long, the blade oblong, 
often nearly as long, crenate, sinuate or even pinnati- 
fid, rough but glabrous; upper leaves smaller, sessile, 
narrowly oblong or lanceolate, crenate or dentate; ra- 
cemes paniculate, terminal and axillary; pedicels very 
slender, ascending, 2’’-3’’ long; flowers white, showy, 
2//-4’’ broad; pods oblong or nearly globose; style 
very short. 
Escaped from gardens into moist grounds, especially 
alongstreams. Frequent. Adventive from Europe. The 
roots furnish the well-known sauce. Summer. 
11. Roripa Americana (A. Gray) Britton. 
Lake Water-cress. (Fig. 1723.) 
Nasturtium natans var. Americanum A. Gray, Ann. 
Lyc. N. ¥. 3:223. 1836. 
Nasturtium lacustre A. Gray, Gen. Ill. 1:132. 1848. 
Roripa Americana Britton, Mem. Torr. Club, 5: 169. 1894. 
leobeckia aquatica Greene, Pittonia, 3:95. 1896. 
Aquatic, branching, 1°-2° long. Immersed leaves 
2/-3/ long, pinnately dissected into numerous fili- 
form divisions; emersed leaves oblong, obtuse or 
acute, 1/-3/ long, entire, serrate or lobed; pedicels 
3/’-4’’ long, slender, widely spreading; flowers white; 
petals longer than the sepals; style slender, about 1// 
long; pods ovoid, 2’’ long, 1-celled. 
In lakes and slow streams, Ferrisburg, Vt.; western 
Quebec and Ontario, northern New York; Sussex Co., 
N. J., to Minnesota, south to Florida and Louisiana. 
Local. Much resembles V. amphibium of Europe, ex- 
cept in its white flowers and smaller upper leaves, which 
are readily detached from the stem. Summer. 
18. CARDAMINE I.. Sp. Pl. 654. 1753. 
Erect or ascending herbs, with scaly or bulbiferous rootstocks or fibrous roots, entire 
lobed or divided leaves, and racemose or corymbose white or purple flowers. Stamens 6, 
rarely 4. Siliques elongated, flat, generally erect; valves nerveless or faintly nerved, elasti- 
cally dehiscent at maturity. Stipe none. Seeds in 1 row in each cell, compressed, margin- 
less; cotyledons accumbent, equal or unequal. [Greek, heart-strengthening, a name for 
some cress supposed to have that quality. ] 
A genus of about 75 species, natives of the temperate regions of both hemispheres. 
% Leaves pinnately divided, or some of them of but a single terminal segment. 
Flowers 6''-9'' broad, white or purplish. 1. C. pratensis, 
Flowers 1'’-4'’ broad, white. 
Leaf-segments numerous, small, the terminal one 2'’-10'’ wide, narrowed, rounded or subcor- 
date at the base. 
Leaves nearly all basal, pubescent. 2. C. hirsuta, 
Stem leafy; leaves glabrous or very nearly so. 
Mature pods erect, %''/-%’’ wide. 
Flowers 2'’-2%s'' wide; plants of swamps, streams, or wet grounds. 
Segments of basal leaves 2'’-12'’ wide; plant 8’-3° tall. 3. C. Pennsylvanica. 
Segments of basal leaves '4''-1'4'’ wide; plant 6’-12' tall. 4. C. arenicola. 
Flowers 1'’-1'4'' wide; plant of dry rocky situations. 5. C. parviflora. 
Mature pods divergent or ascending, more than '%4’’ wide. 6. C. flexuosa. 
Leaf-segments few, large, the terminal one 1'-2' wide, deeply cordate. 7. C. Clematitis. 
%% Leaves entire, toothed, or rarely with 1 or 2 lateral segments. 
Dwarf, alpine; leaves nearly entire, long-petioled. 8. C. bellidifolia, 
Erect or decumbent; leaves more or less toothed or lobed. 
Flowers purple; stem erect. g. C. Douglassii. 
Flowers white. 
Stem erect from a tuberous base. 10. C. bulbosa. 
Stem decumbent, stoloniferous; roots fibrous. 11. C. rotundifolia, 
