2(1). Calyx 1.5-2 mm. long in flower (to 2.5 mm. in fruit); creeping stems 

 mostly less than 1 mm. thick 2. D. micrantha. 



2. Calyx 2.5-3.2 mm. long in flower (to 3.8 mm. in fruit); creeping stems 1-2 

 mm. thick 3. D. recurvata. 



1. Dichondra carolinensis Michx. 



Rooting at the nodes, mat-forming, 1-12 cm. high, sparsely pubescent; pedicels 

 one third to two thirds as long as petioles in flower; corolla nearly as long as calyx, 

 light-green. D. repens var. carolinensis (Michx.) Choisy. 



Damp open ground, in mud on edge of lakes and ponds, edge of swamps and 

 marshes, roadsides and lawns, s.e. Okla. (McCurtain Co.) and cen. and e. Tex., 

 Mar.-June; e. and n. to Fla. and Va. 



2. Dichondra micrantha Urban. 



Rooting at the nodes, mat-forming, 1-6 cm. high, sparsely pubescent; pedicels 

 subsessile to one fourth or one half as long as petioles; corolla as long as calyx or 

 slightly longer, white. 



Damp ground and lawns, bogs and wet meadows, s. Tex., Apr.-May; adj. Mex., 

 W.I.. Pac. Is., e. Asia. 



3. Dichondra recurvata Tharp & M. C. Johnst. 



Rooting at the nodes, mat-forming, 2-17 cm. high, rather sparsely pubescent; 

 pedicels one tenth to one half as long as petioles; corolla nearly one third longer 

 than calyx. 



Gravelly or sandy open oak woods, wet meadows and wet sandy gravel along 

 creeks, cen. Tex., Mar. -May; endemic. 



2. Cressa L. 



Low densely appressed-pubescent perennials with deep vertical or oblique branch- 

 ing rhizomes, forming colonies, aboveground stems erect or partly decumbent, 

 freely branched; leaves sessile, small, entire; flowers axillary, solitary, short- 

 pedicelled; calyx bracteolate; sepals 5, united at base, laterally overlapping, elliptic; 

 corolla white, funnelform to subsalverform, 5-lobed. exceeding calyx; stamens 

 exserted; styles 2; stigma capitate; capsule 1- to 4-seeded. 



About 6 species in warm-temperate to tropical regions of both hemispheres. 



I. Leaf blades well-developed, broadly elliptic to lanceolate, the larger 5-12 mm. 

 long and 1.5-6 mm. wide, those on main stems crowded and over- 

 lapping 1. C. depressa. 



1. Leaf blades very reduced, at flowering time the plant usually with only small 

 bracts 1-4 mm. long and 0.6-2.8 mm. wide, those on main stems 

 widely spaced 2. C. nudicaulis. 



1. Cressa depressa Goodd. Alkali weed. Fig. 638. 



Plant densely leafy, gray-pubescent, 8-25 cm. tall. C. truxillensis H.B.K. var. 

 vallicola (Heller) Munz. 



In depressions or damp or wet strongly alkaline soil and in wet heavy soils of 

 river valleys and canal banks, in s.w. Okla. (Waterfall), the Tex Trans-Pecos, 

 N. M. (Dona Ana Co.) and Ariz. (Coconino, Mohave, Maricopa, Pinal and Yuma 

 COS.), Apr.-July; w. to Calif.; Mex. 



2. Cressa nudicaulis Griseb. Leafless cressa. Fig. 638. 



Plant at first with a few very small leaves, appearing leafless or nearly so at 

 flowering time, with bracts only, 7-20 cm. tall. C. aphylla Heller. 



On brackish clay banks and flats just above water and periodically wetted, in 

 coastal COS. of Tex. from San Patricio Co. s., Apr.-May or Sept.; also Arg. 



1351 



