138 BBASSICACEAE. 



sepals narrow, 5-6 mm. long: petals oblong-spatulate, 12-15 mm. long: pods 

 3-5 cm. long, slender-beaked. Common, on moist banks and in woods. 

 Spr. TOOTHWORT. 



23. ARABIS L. Annual or perennial herbs. Leaf -blades entire, toothed, 

 or pinnatifid. Sepals 4, erect, broad or narrow. Petals 4, white, pink, purple, 

 or yellowish, as long as the sepals or much longer. Stamens 6: anthers ovoid 

 to oblong. Style very short or obsolete : pod elongate. Spr. and sum. 

 KOCK-CRESS. 



Basal leaves with pinnatifid blades : petals broad. 1. A. lyrata. 



Basal leaves with toothed blades : petals narrow. 



Capsules erect or nearly so, sometimes appressed. 



Seeds marginless : petals less than 4 mm. long : pods 



very short-pedicelled 2. A. dentata. 



Seeds margined : petals over 6 mm. long : pods long- 



pedicelled. 

 Corollas over 7 mm. broad : capsules not appressed : 



style 1 mm. long. 3. A. patens. 



Corollas less than 7 mm. broad: capsules appressed: 



stigma sessile. 4. A. hirsuta. 



Capsules recurved. 



Outer sepals narrow, linear : plants glabrous, glaucous : 



pods 1-2 mm. wide. 5. A. laevigata. 



Outer sepals broad, ovate to oblong-ovate : plants pubes- 

 cent, at least below : pods 2.5-3.5 mm. wide. 6. A. canadensis. 



1. A. lyrata L. Stems 1-4 dm. tall, mostly pubescent near the base: blades of 

 the cauline leaves linear-spatulate to linear, entire or nearly so: sepals becom- 

 ing 2.5-3 mm. long: petals white, 6-8 mm. long, narrowly obovate: pods nar- 

 rowly linear, 2-3 cm. long. Common, on rocks and rocky hillsides. 



2. A. dentata T. & G. Stems 2-6 dm. tall, stellate-pubescent: blades of the 

 cauline leaves 2-8 cm. long, spatulate to cuneate or oblong, irregularly finely 

 dentate, clasping: sepals becoming 2-2.5 mm. long: petals 3-4 mm. long, 

 spatulate: pods linear, 2-2.5 cm. long. Lower Susquehanna valley. Occa- 

 sional, in woods. Schists. Spr. 



3. A. patens Sulliv. Stems 3-7 dm. tall, pubescent with simple or branched 

 hairs: blades of the cauline leaves oblanceolate or cuneate to lanceolate or 

 ovate, 1-6 cm. long, mostly coarsely serrate, sessile: sepals becoming 4-5 mm. 

 long: petals 6-8 mm. long, narrowly cuneate: pods narrowly linear, 2.5-4 cm. 

 long. Lower Susquehanna valley. Frequent, especially on Mountain island 

 at Peach Bottom. Schists. 



4. A. hirsuta (L.) Scop. Stems 3-8 dm. tall, usually sparingly hirsute: blades 

 of the cauline leaves oblanceolate to oblong or lanceolate, 1-6 cm. long, nearly 

 Entire or dentate, auricled-clasping : sepals becoming 3 mm. long: petals about 

 twice as long as the sepals, spatulate: pods narrowly linear, 2.5-4 cm. long. 

 M. Frequent, on creek banks. Limestones. 



5. A. laevigata (Muhl.) Poir. ' Stems 3-10 dm. tall, glabrous: blades of the 

 cauline leaves oblong to lanceolate or linear, 3-15 cm. long, entire or coarsely 

 toothed, clasping: sepals glabrous, becoming 4-5 mm. long: petals 6-10 mm. 

 long, spatulate: pods very narrowly linear, 6-10 cm. long, thick: seeds oblong, 

 narrowly winged. Common, in woods and on rocky banks. 



6. A. canadensis L. Stems 2-9 dm. tall, often sparingly pubescent: blades of 

 the cauline leaves oblanceolate to oblong or lanceolate, 3-12 cm. long, remotely 

 toothed or nearly entire, not clasping: sepals pubescent, becoming 4 mm. 

 long: petals 6-8 mm. long, oblong to oblong-spatulate: pods scythe-shaped, 

 flat, 5-10 cm. long: seeds ovate or orbicular, broadly winged. Common, in 

 woods and thickets. 



