CRUCIFERAE. 4 6 3 



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 1 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. 



1. StenophragmaTr.aliana(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. [Arabis Thaliana L.J 



33. ARABIS L. 



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

 elongated, flat; valves smooth, keeled or ribbed, mostly 1 -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 1 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, 1 mm. broad. 



Flowers white, 8 mm. broad ; pods not appressed ; style 1 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. 11. 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. Tex. and Lower Cal. March-May. [A. Ludoviciana Meyer.] 



2. Arabis lyrata L. Lyre-leaved Rock-cress. (1. F. f. 1772.) Tufted, 

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

 leaves lyrate-pinnatifid. 2-5 cm. long, spatulate or oblanceolate; stem-leaves spatu- 

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

 mm. broad; petals much exceeding the calyx; pods 1.5-3 cm - lon k r - 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- 

 bept. 



