MUSTARD FAMILY 285 



anthers short, rounded. Style slender; stigma obscurely lobed. Silique 2-valved and 

 partly or completely 2-celled or 4-valved and 1-celled. Seeds flattened, not winged ; cotyle- 

 dons incumbent. [Greek, meaning keeled fruit.] 



Two species, natives of California. Type species, Tropidocarpum gracile Hook. 



Pods strongly obcompressed, 2-valved. 1- T. gracile. 



Pods more or less turgid, 4-valved. 2 - T. capparideum. 



1. Tropidocarpum gracile Hook. Slender Tropidocarpum. Fig. 2045. 



Tropidocarpum gracile Hook. Ic. PI. 1: pi. 43. 1836. 



Tropidocarpum scabriusculum Hook. Ic. PI. 1: pi. 52. 1836. 



Tropidocarpum macrocarpum Hook. & Harv. ex Greene, Proc. Acad. Phila. 1895: 553. 1896. 



Stems slender, erect or spreading, 15-45 cm. long, more or less hirsute-pubescent with inter- 

 mingling simple and forked hairs. Leaves shallowly or deeply pinnatifid, the segments cleft or 

 entire, those subtending the flowers reduced; pedicels slender, 6-20 mm. long; pods linear to 

 linear-lanceolate, 1-3 cm. long or strongly obcompressed and 2-celled throughout. 



Grassy plains and hillsides, Upper Sonoran Zone; North Coast Ranges and the Sacramento Valley, south 

 to northern Lower California, extending eastward to Inyo County and the Mojave Desert. Type locality: 

 Monterey, California. March-May. 



Tropidocarpum gracile var. dubium (Davidson) Jepson, Man. Fl. PI. Calif. 434. 1925. Differing from 

 th« typical species by the twisted pods which are 2-celled and obcompressed above the middle, by a twist be- 

 coming compressed below and 1-celled. San Joaquin Valley and southern California. 



2. Tropidocarpum capparideum Greene. Caper-fruited Tropidocarpum. 



Fig. 2046. 



Tropidocarpum capparideum Greene, Pittonia 1: 217. 1888. 



Stems erect or decumbent, branching, pilose with intermingling forked and simple hairs. 

 Leaves pinnatifid, the lobes simple or toothed, those subtending the flowers reduced; pedicels 

 slender, equaling or exceeding the subtending leaflets ; petals 3-4 mm. long, slightly exceeding the 

 sepals; pods linear-oblong, 15-20 mm. long, turgid, 4-valved, 1-celled with 4 parietal placentae, 

 the valves 1 -nerved; style slender, 1-2 mm. long. 



Alkaline soils, San Joaquin Valley, California. Type locality: "somewhat alkaline valley lands, skirting 

 the San Joaquin River, Contra Costa County, California." March-April. 



31. LYROCARPA Hook. & Harv. Lond. Journ. Bot. 4: 76. pi 4. 1845. 



Erect annual or perennial herbs with stellate pubescence. Leaves irregularly toothed 

 or runcinate-pinnatifid. Racemes elongated in fruit. Sepals connivent, linear, acute. 

 Petals ligulate or nearly so. Style short ; stigma large, lobed. Pods lyrate or broadly reni- 

 form-obcordate, flattened contrary to the partition. Seeds strongly flattened and narrowly 

 winged ; cotyledons accumbent. [Greek, meaning lyre and fruit.] 



Three species, natives of the arid southwestern United States and adjacent Mexico. Type species, Lyro- 

 carpa Coulteri Hook. & Harv. 



1. Lyrocarpa Coulteri Hook. & Harv. Coulter's Lyre-pod. Fig. 2047. 



Lyrocarpa Coulteri Hook. & Harv. Lond. Journ. Bot. 4: 76. pi. 4. 1845. 



Perennial with a short woody caudex, flowering stems several, more or less flexuous, 2-5 

 dm. long, whole plant cinereous with a more or less dense stellate pubescence. Leaves lanceolate 

 in outline, toothed to pinnatifid, 3-7 cm. long; racemes loose, elongated in fruit; sepals 8 mm. 

 long; petals about twice as long, ligulate, purplish yellow; pods lyrate, 10-15 mm. wide at the 

 apex, 15-20 mm. long. 



Dry rocky situations. Lower Sonoran Zone; Colorado Desert, southern California, to Sonora and northern 

 Lower California. Type locality: California. Jan.-April. 



32. DITHYREA Harv. Lond. Journ. Bot. 4: 77. pi. 5. 1845. 



Stellate-pubescent annuals or perennials, with branching stems. Flowers perfect, 

 racemose. Sepals erect or connivent above, ovate or oblong, petals broadly spatulate, 

 with slender claws, white or purplish. Stamens 6; anthers linear, sagittate. Stigma ses- 

 sile, helmet-shaped. Pod didymous, strongly obcompressed, the cells suborbicular, with a 

 prominent cord-like margin. Seeds solitary in each cell; cotyledons accumbent. [Greek, 

 meaning two shields, in reference to the shape of the pods.] 



A genus of two species, natives of the southwestern United States. Type species, Dithyrea califomica 

 Harv. 



1. Dithyrea califomica Harv. California Shield-pod. Fig. 2048. 



Dithyrea califomica Harv. Lond. Journ. Bot. 4: 77. 1845. 

 Biscutella califomica Brewer & Wats. Bot. Calif. 1 : 48. 1876. 



Annual, the stems branching from the base, spreading or ascending, 1-4 dm. long. Leaves 

 2.5-7 cm. long, ovate to oblong-ovate, coarsely and shallowly few-toothed, the basal on petioles 



