CK UCIFERA E. 463 



32. STENOPHRAGMA Celak. 



Herbs with the aspect of some species of Arabis, pubescent with forked hairs, 

 with slender stems, and small white flowers in terminal racemes. Style very 

 short; stigma 2-lobed. Siliques narrowly linear, dehiscent, the valves rounded, 

 nerveless. Seeds in I row in each cell in the following species, in some European 

 species in 2 rows; cotyledons incumbent. [Greek, narrow septum.] About 10 

 species, natives of Europe and Asia, the following are annual weed. 



i. StenophragmaThaliana(L.) Celak. MOUSE-EAR CRESS. (I. F. f. 1770.) 

 Stem erect, 2-40 cm. high, freely branching, pubescent, especially below. Basal 

 leaves 2-5 cm. long, obtuse, oblanceolate or oblong, narrowed into a petiole, entire 

 or slightly toothed; stem-leaves smaller, sessile, often entire; pedicels slender, 

 spreading or ascending, 4-8 mm. long in fruit; flowers white, about 3 mm. long; 

 petals about twice the length of the sepals; pods 8-20 mm. long, acute, often 

 curved upward, glabrous. In sandy fields and rocky places, Mass, and S. Ont. to 

 Minn., Ga. and Mo. Nat. from Europe. April-May. 



33. A'RABIS L. 



Glabrous or pubescent herbs, with white or purple flowers. Siliques linear, 

 elongated, flat; valves smooth, keeled or ribbed, mostly I -nerved, not elastically 

 dehiscent. Seeds in i or 2 rows in each cell, flattened, winged; cotyledons accum- 

 bent. [Name from Arabia.] About 80 species, mainly natives of the northern 

 hemisphere. In addition to the following, about 26 others occur in the northern 

 and western parts of the continent. 



Seeds in i row, or in 2 incomplete rows in each cavity of the pod. 

 Basal leaves pinnatifid ; pods ascending. 



Seeds about 2 mm. broad, orbicular, wing-margined ; stem-leaves pinnatifid. 



1. A. Virginica. 

 Seeds minute, oblong, wingless ; stem-leaves entire, or dentate. 



2. A. lyrata. 

 Leaves small, mostly entire ; pods drooping ; seeds oblong, wingless ; arctic. 



3. A. arenicola. 

 Basal leaves merely dentate or lyrate. 



Seeds minute, oblong, wingless. 4. A, dentata. 



Seeds larger, oblong, winged or margined. 



Pods curved upward, nearly 2 mm. broad. 5. A. alpina. 



Pods nearly erect, i mm. broad. 



Flowers white, 8 mm. broad ; pods not appressed ; style i mm. long. 



6. A. patens, 

 Flowers white or greenish- white, 4-6 mm. broad ; pods appressed ; style 



none. 7. A. hirsuta. 



Pods recurved-spreading. 



Plant glabrous throughout. 8. A. laevigata. 



Leaves and lower part of stem hairy. 9. A. Canadensis. 



Seeds in 2 distinct rows in each cavity of the pod. 



Pods spreading or ascending; seeds winged. 10. A. brachycarpa. 



Pods erect, appressed ; seeds wingless or narrowly winged. n. A. glabra. 

 Pods reflexed ; seeds winged. 12. A. Holboellii. 



1. Arabis Virginica (L.) Trelease. VIRGINIA ROCK-CRESS. (I. F. f. 1771.) 



Annual or biennial, diffuse, glabrate; stems ascending, 1.5-3 dm. high. Leaves 

 oblong, narrow, deeply pinnatifid, 2-8 cm. long, the lower petioled, the upper 

 nearly sessile, sometimes reduced to lobed or entire bracts; pedicels 4 mm. long in 

 fruit; flowers very small, white; pods linear, ascending, 1.5-2.5 cm. long, about 

 2 mm. broad ; seeds nearly as broad as the pod. In open places, Va. and Ky. to 

 Kans., Fla. and Tex., west to Lower Cal. March-May. 



2. Arabis lyrata L. LYRE-LEAVED ROCK-CRESS. (I. F. f. 1772.) Tufted, 

 perennial or biennial, erect, 1-3 dm. high, glabrous, or pubescent below. Basal 

 leaves lyrate-pinnatifid, 25 cm. long, spatulate or oblanceolate; stem-leaves spatu- 

 late or linear, 1-2.5 cm. long; pedicels 6-8 mm. long in flower; flowers white, 6-8 

 mm. broad; petals much exceeding the calyx; pods 1.5-3 cm - l n g> linear, less 

 than 2 mm. broad, their valves firm, nerved; style I mm. long; seeds 0.5 mm. 

 long. Rocky and sandy places, Ont. to Va., Tenn., Manitoba and Mo. April- 

 Sept. 



