CRUCIFER AE 
39 
CRUCIFERAE. MUSTARD FAMILY 
Herbs with pungent juice and alternate leaves. Flowers in terminal 
leafless racemes, 4 sepals, 4 petals, 6 stamens (4 long and 2 short, or 
sometimes only 4 or 2). Pod 2-celled by a thin partition and splitting 
open by valves from the base. Some genera have a 1-celled pod which 
does not split open.—This family, which comprises about 1600 species, 
occurs in cold and temperate regions of all continents. The herbage is 
characterized by a pungent juice, antiscorbutic in its properties, which 
is present in some degree in every member of this family. Its presence 
is a more infallible mark of the family than any structural character. 
A. Pods enlongated or linear. 
Filaments with 1 or 2 pairs united; sepals strongly saccate at base, making a some¬ 
what flask-shaped flower.1. Streptanthus. 
Filaments all distinct. 
Pods somewhat corky, not splitting lengthwise.4. Raphanus. 
Pods splitting lengthwise, the 2 valves falling away and leaving the partition. 
Pods pointed with a long beak prolonged much beyond the valves-; 
flowers large, yellow.:.5. Brassica. 
Pods not beaked. 
Stems from annual roots or perennial root-crowns. 
Valves of the pod nerved. 
Pod valves more or less distinctly 3-nerved ; leaves pinnatifid 
or pinnately dissected; flowers yellow ; pods terete. .. 
3. Sisymbrium. 
Pod valves 1-nerved. 
Seeds commonly in 1 row in each cell (but see no. 8). 
Leaves pinnatifid (at least the lower) ; flowers small. 
Flowers yellow ; pods somewhat quadrangular, 
pointed ; perennial.6. Barbarea. 
Flowers white or yellowish; pods terete; ours 
annuals or perennials. 
2. Thelypodium. 
•Leaves commonly entire or toothed. 
Flowers orange or yellow.7. Erysimum, 
Flowers white or whitish or purple.. 8 . Arabis. 
Seeds in 2 rows in each cell; plants of wet places. 
11. Radicula. 
Valves of the pods not nerved; flowers white; leaves pinnate. 
9. Cardamine. 
Stems from tuberous rootstocks; some of the leaves 3-foliolate. 
10. Dentaria. 
B. Pods very short, nearly or quite as broad as long. 
Pods splitting open by valves. . . , . .. . , 
Pods flattened parallel to the broad partition ; flowers white or yellowish. 
12. Alyssum. 
Pods flattened contrary to the narrow partition. 
Pods obcordate or elliptical, several-seeded.13. Capsella. 
Pods roundish or ovate, notched or winged at summit, 2-seeded. 
14. Lepidium. 
Pods not splitting open, bordered by a wing.15. Thysanocarpus. 
1. STREPTANTHUS Nutt. 
Ours annuals, the basal leaves toothed or pinnatifid, those of the stem 
similar or entire, often clasping by a sagittate base. Flowers in terminal 
racemes. Sepals usually of the same color as the petals, strongly saccate 
at base and contracted above, the flower thus becoming somewhat flask- 
