MUSTARD FAMILY 303 



cm. high. Basal leaves petioled, 5-10 cm. long, oblanceolate to oblong, dentate or sometimes 

 lyrate, pubescent with simple hairs ; stem leaves sessile, sagittate, lanceolate or oblong, all but 

 the lowest glabrous; petals yellowish white, 3 mm. long; pedicels erect, 4-12 mm. long; pods 

 erect, 4-10 cm. long, 1.5-2 mm. wide. 



Fields and grassy slopes, Boreal and Austral Zones; British Columbia to Quebec, southern California, and 

 Pennsylvania; also in Europe and Asia. March-Aug. 



46. ARABIS L. Sp. PI. 664. 1753. 



Annual or perennial herbs, glabrous or pubescent with forked hairs, with simple 

 mostly toothed leaves and white or purplish flowers. Stamens 6 ; filaments unappendaged. 

 Pods sessile, elongated, flattened parallel with the partition, the valves usually 1 -nerved, 

 dehiscent but not elastic; stigma entire or 2-lobed. Seeds in 1 or 2 rows in each cell, 

 winged or wingless ; cotyledons accumbent. [Name from Arabia.] 



A genus of about 120 species, mainly natives of the northern hemisphere. Type species, Arabis alpina L. 



Delicate annuals; leaves at least the lower pinnate or pinnatifid. 



Seeds oblong-ellipsoid, wingless. I. Filifoliae. 



Seeds orbicular, narrowly winged. II. Virginicae. 



Perennials or a few biennials. 



Basal leaves lyrately lobed; seeds oblong, wingless. III. Lyratae. 



Basal leaves entire or toothed. 

 Pods erect or nearly so. 



Leaves coarsely hirsute with simple or mostly simple hairs, sometimes glabrous. 



Stem leaves neither cordate nor auriculate. IV. Furcatae. 



Stem leaves cordate or auriculate. V. Hirsutae. 



Leaves pubescent with more or less forked or stellate hairs, sometimes glabrous. 

 Styles obsolete or short, not filiform. 

 Pods 1—2.5 mm. wide. 



Stem leaves not auriculate. 



Pods 1 mm. wide; flowers white. VI. Whitedianae. 



Pods 2-2.5 mm. wide; flowers purple. VII. Blepharophyllae. 



Stem leaves auriculate. VIII. Drummondianae. 



Pods 4-5 mm. wide. IX. Platyspermae. 



Styles filiform, 4-6 mm. long. X. Parishianae. 



Pods spreading or reflexed. 



Stem leaves not auriculate. 



Leaves all wing-petioled, usually repand; pods glabrous. XL Repandentes. 



Leaves sessile, entire; pods usually stellate. XII. Pulchrae. 



Stem leaves auriculate-clasping. 



Pods stellate-pubescent. XIII. Subpinnatifidae. 



Pods glabrous. 



Pods 3-4 mm. wide. XIV. Suffrutescentes. 



Pods 1-2.5 mm. wide. 



Pods spreading or somewhat recurved on spreading pedicels. 

 Perennials with a caudex. 



Plants suffruticose at the base, 3 dm. or more high. 



XV. Perejnnantes. 

 Plants cespitose, 1-2 dm. high. XVI. Reconditae. 



Biennials or short-lived perennials, stout, 3 dm. or more high. 



XVII. Arcuatae. 

 Pods and pedicels strongly reflexed. XVIII. Retrofractae. 



I. Filifoliae. 



Leaves all pinnately divided into filiform segments; glabrous plants. 1. A. filifolia. 



Leaves at base pinnately divided into linear or lanceolate lobes, those subtending the branches mainly entire; 

 plant inconspicuously and often sparsely puberulent with forked hairs. 2. A. deserti. 



II. Virginicae. 



Annual, spreading, pubescent; leaves pinnately divided or pinnatifid. 3. A. virginica. 



III. Lyratae. 



Perennials; basal leaves lyrate-pinnatifid, those of the stem simple. 4. A. lyrata kamchatica. 



IV. Furcatae. 



Perennials, more or less cespitose; seeds oblong, wingless or winged only at the base. 



Seeds wingless; basal leaves hirsute. 



Petals 4—6 mm. long. 5. A. Nuttallii. 



Petals 3—4 mm. long. 6. A, macella. 



Seeds winged on the lower margin. 



Basal leaves merely ciliate on the margin; flowers white. 



Petals 2 mm. long, equaling the sepals. 7. A. olympica. 



Petals 6-12 mm. long. 8. A. furcata. 



Basal leaves hirsute; flowers deep rose-purple. 9. A. aculeolata. 



Biennials from a taproot and usually with a simple crown; seeds orbicular, winged all around. 



10. A. Cusickii. 



