704 MISC. PUBLICATION 42 3, U. S. DEPT. OF AGRICULTURE 



It occurs most commonly on Boerhaavia but is found occasionally 

 on other hosts, such as Euphorbia. Flowers cylindric, on slender 

 pedicels; calyx thickened and keeled toward the base; corolla papillose 

 in the basal, calyx-enveloped part; stamens somewhat shorter than 

 or equaling the corolla lobes; styles slender, longer than the ovary, 

 exserted; capsule globose, enveloped and surmounted by the withered 

 corolla. 



2. DICHONDRA 



Plants perennial, more or less sericeous; stems creeping, rooting at 

 the nodes; leaves petioled, the blades round-renif orm ; flowers small, 

 solitary on bractless peduncles, the corolla broadly campanulate, 

 whitish; pistils separate or nearly so; capsules 1- or 2-seeded. 



These plants are very efficient soil binders but are rare in Arizona. 



Key to the species 



1. Stems and petioles relatively stout, the petioles straight or nearly so; leaf blades 

 densely silvery-sericeous on both faces, with a very shallow sinus or nearly 

 truncate at base; corolla very villous outside; peduncles stout, about 5 mm. 



long, strongly decurved after flowering 1. D. argentea. 



1. Stems and petioles slender, the petioles mostly curved; leaf blades bright green 

 and sparsely sericeous above, with a deep, broad or narrow sinus; corolla 

 glabrous or sparsely villous outside (2) . 

 2. Leaf blades silvery-sericeous beneath, seldom more than 2 cm. wide; pe- 

 duncles filiform, commonly more than 1 cm. long 2. D. repens. 



2. Leaf blades green and sparsely sericeous beneath, commonly more than 

 2 (up to 5) cm. wide; peduncles relatively stout, mostly less than 1 

 cm. long 3. D. brachypoda. 



1. Dichondra argentea Willd., Hort. Berol. pi. 81. 1816. 

 Foothills near Bisbee, Cochise County (Harrison 8256), about 5,300 



feet, late summer. Western Texas to southeastern Arizona and 

 Mexico. 



2. Dichondra repens Forst., Char. Gen. PL 39. 1776. 



Sycamore Canyon near Ruby, Santa Cruz County, about 4,000 feet 

 (Goodding 6620). Widely distributed in tropical America. 

 The collection cited belongs to var. sericea (Swartz) Choisy. 



3. Dichondra brachypoda Woot. and Standi., Contrib. U. S. Natl. 



Herbarium 16: 160. 1913. 

 Near San Bernardino, Cochise County, about 4,000 feet, in a canyon 

 (Goodding 6629). Western Texas to southeastern Arizona and 

 northern Mexico. 



3. EVOLVULTJS1 4 



Small pubescent perennial herbs; stems numerous, erect or diffuse, 

 never twining; flowers solitary or few in a cluster, subsessile to long- 

 pedunculate; corolla rotate-camp anulate or broadly funnelform, 

 cream-colored, purple, or sky blue; styles 2, each 2-cleft. 



The plants are sun loving, growing on dry plains and mesas, often 

 among grasses. 



1 4 Reference: Van Ooststroom, S. J. A monograph of the genus evolvulus. Meddel. Bot. Mus. 

 Herb. Rijksuniv. Utrecht 14: 1-267. 1934. 



