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



6. Flowers on long slender divaricate pedicels; fruits hispid with hooked 

 hairs, didymous; stipules small, interpetiolar (not forming a sheath 



around the stem), entire or few-toothed 5.Kelloggia. 



6. Flowers sessile or nearly so, in axillary or terminal cy mules (rarely 



solitary in the leaf axils) ; fruits not hispid with hooked hairs ; stipules 



connate, forming a sheath around the stem, cuspidate or setose (7). 



7. Fruit circumscissile, the upper part falling off with the calyx limb; 



seeds about as wide as long, 4-lobed 8. Mitracarpus. 



7. Fruit not circumscissile, the carpels separating partly or completely 

 by longitudinal cleavage; seeds elongate, not lobed (8). 

 8. Calyx limb with the teeth united at base, deciduous at or before 



the separation of the carpels 6. Crusea. 



8. Calyx limb of separate or nearly separate teeth, these persistent 

 even after the carpels separate. _ 7. Diodia. 



1. OLDENLANDIA 



Plant annual, small, glabrous; stems slender, erect, often diffusely 

 branched; leaves opposite, the blades narrow; flowers small, all alike, 

 in terminal cymes or solitary in the forks; calyx teeth subulate; corolla 

 whitish, sal verform ; capsule hemispheric and somewhat quadrangular 



1. Oldenlandia green ei A. Gray, Amer. Acad. Arts and Sci. Proc. 19: 



77. 1883. 

 Cochise, Santa Cruz, and Pima Counties, 5,000 to 6,000 feet, rich 

 soil in woods, August and September. Southern New Mexico and 

 Arizona (doubtless also in northern Mexico). 



2. HOUSTONIA 



Plants perennial, cespitose, herbaceous or barely suffrutescent ; 

 stems short, diffuse or procumbent; leaves opposite, or appearing 

 fascicled due to the shortening of the internodes; flowers dimorphic 

 in the relative length of the stamens and the style, some of them cleis- 

 togamous; corolla white to deep pink, salverform; peduncles recurved 

 in fruit; capsules didymous. 



Key to the species 



1. Plant rather densely cespitose, subacaulescent; leaves mostly basal or nearly 

 so, erect; corolla bright pink, tubular-salverform, the tube very slender, 

 10 to 24 mm. long, about 3 times as long as the lobes 1. H. rubra. 



1. Plant loosely cespitose, caulescent, the stems leafy, up to 20 cm. long; leaves 

 spreading or ascending; corolla white or pinkish, funnelform-sal verform, 

 the tube 3 to 4 mm. long, not more than one and one-half times as long as 

 the lobes 2. H. wrightii. 



1. Houstonia rubra Cav., Icon. PL 5: 48. 1799. 



Navajo, Cochise, and Santa Cruz Counties (doubtless elsewhere), 

 4,000 to 6,000 feet, mesas and dry rocky hills, often in sandy soil, 

 May to July. New Mexico, Arizona, and Mexico. 



2. Houstonia wrightii A. Gray, Amer. Acad. Arts and Sci. Proc. 17: 



202. 1882. 

 Apache County to Coconino County, south to Cocihise and Pima 

 Counties, 5,000 to 7,500 feet, dry mesas and slopes, among chaparral 

 shrubs, oaks, or pines, common, June to September. Western Texas 

 to Arizona and Mexico. 



