MUSTARD FAMILY " 347 



Pods pubascent; plant glabrous and glaucous. 1. T. trichocarpus . 



Pods glabrous. 



Plant more or less hirsute; pod entire-margined, fenestrate, or with thin round 

 areas. 2. T. elegans. 



Plant glabrous ; pod toothed, rarely with fenestrations or thin areas. 3. T. amplectens. 



1. T. trichocarpus Rydb. Stem 1-3 dm. high; lower leaves oblanceolate 

 or oblong, sinuately dentate; uppermost leaves linear or linear-lanceolate, entire; 

 petals slightly over 1 mm. long; pedicels in fruit about 5 mm. long, recurved; 

 pod nearly orbicular, about 4 mm. wide, short-pubescent; wing-margins crenate 

 or lobed, not fenestrate. Dry places: Utah — Ida. Son. — Submont. My. 



2. T. elegans F. & M. Stem 3-6 dm. high; basal leaves oblanceolate, 

 3-10 cm. long; upper leaves lanceolate, sagittate at the base; petals spatulate, 

 2 mm. long, white or pinkish; pod nearly orbicular, 5 mm. wide; wing with 12-14 

 fenestrations or thinner areas. Sandy or rocky groimd: Cahf.— Wash. — Ida. 

 Son. Mr-My. 



3. T. amplectens Greene. Stem 3-5 dm. high; basal leaves oblanceolate, 

 coarsely sinuate-dentate, 2-5 cm. long; stem-leaves linear-lanceolate, auriculate 

 at the base; petals spatulate, about 1.5 mm. long; pods orbicular, with a short 

 cuneate base, crenate on the margin, 5 mm. broad. Sandy places: Ariz. — ■ 

 Utah— N.M. Son.— Submont. Mr-Je. 



34. ALYSSUM L. Alyssum, Sweet Alyssum. 



Densely stellate annuals or perennials, with alternate leaves. Flowers 

 perfect in racemes. Sepals ovate or oblong, more or less spreading. Petals 

 whitish, obovate or cuneate to linear. Stamens 6; filaments commonly dilated 

 at the base, in our species not toothed. Fruit orbicular, 2-celled, dehiscent; 

 valves convex. Cotyledons accumbent. 



1. A. alyssoides (L.) Gouan. Branched annual; stems 1-3 dm. high; leaves 

 linear-oblong or spatulate, 1-3 cm. long, densely stellate-can escent, entire; 

 petals white, or at first yellowish, 3.5 mm. long; pod orbicular in outline, 3 mm. 

 broad, notched at the apex. A. calycinum L. Fields and waste places: N.H. — 

 N.J. — Utah — Calif. — B.C.; nat. from Eu. Plain — Submont. My-Je. 



35. BERTEROA DC. Hoary Alyssum. 



Annual or perennial herbs, stellate or canescent with forked hairs. Leaves 

 alternate, entire. Flowers racemose, perfect. Sepals ascending in anthesis, 

 equal. Petals white, notched. Stamens 6; filaments 2-toothed at the base. 

 Pod oblong (in ours) to nearly globose, only shghtly compressed. Seeds winged, 

 several. Cotyledons accumbent. 



1. B. incana (L.) DC. Stem 3-6 dm. high, branched; leaves numerous, 

 entire, lanceolate or lance-elliptic, pale green, or the lower oblanceolate, petioled; 

 petals 2-3 mm. long, white; pod oblong, 6-8 mm. long, 2.5-3.5 mm. thick, canes- 

 cent. Waste places and around dwellings: Me. — N.J. — Mo. — Mont.; adv. or 

 nat. from Eu. Je-S. 



36. IDAHOA Nels. & Macb. Flat-pod. 



Low scapose annual, with lyrate basal leaves. Flowers perfect, solitary. 

 Sepals broad, erect. Petals small, spatulate, white. Pods suborbicular, strongly 

 flattened paralleUy to the partition. Seeds in two rows, reticulate, broadly 

 winged. Cotyledons accumbent. [Platyspermuyn Hook., not Hoffm.] 



1, I. platysperma (Hook.) Nels. & Macb. Acaulescent, scapiferous annual; 

 leaves basal, petioled, with hastate or lyrate or rarely entire and ovate blades; 

 scapes 2-15 cm. long; sepals 2 mm. long, nearly equalling the white spatulate 

 petals; pod rounded-ovate, 6-10 mm. long, 5-8 mm. wide; seeds broadly winged, 

 5 mm. broad. Platyspcrmum scapigerum Hook. Prairies and hillsides: Ore. 

 —Calif.— Nev.— Ida. Ap-My. 



37. DENTARIA L. Toothwort, Milk Maids. 



Erect scapose, perennial herbs, with often thickened rootstocks. Leaves 

 basal; blades palmately cleft or divided. Bracts leaf-like, subopposite or sub- 



