nerved at the lower nodes with a rosette of floating obovate leaves, or (on plants 

 stranded on the mud) all linear or all obovate or oblong; linear one-nerved leaves 

 shallowly bidentate at tip with an enlarged but scarcely excurrent nerve ending. 



In quiet waters and on mud throughout Tex. and Okla., N.M. (Catron and Taos 

 cos.) and Ariz. (Coconino, Gila, Pima and Santa Cruz cos.), Feb.-Sept.; from 

 e. Can. throughout the U.S., s. through Mex. to Guat. 



4. Callitriche peploides Nutt. Fig. 513. 



Fruit black when ripe, 0.5-0.8 mm. wide, not quite so high; mericarps nar- 

 rowed and elongate at base, pushing against each other so that each is bent at an 

 angle with the face and the fruit appears greatly thickened at base; stigmas about 

 0.2 mm. long, often persistent and loosely reflexed; filaments about 0.2 mm. long; 

 anther about 0.1 mm. wide; stems rooting below and apparently creeping, the 

 erect branches 1-5 cm. high; leaves only slightly crowded at the tips of the 

 branches, 2-5 mm. long, cuneate to spatulate-obovate, 1- to 3-nerved but often so 

 faintly so as to appear nerveless. 



On mud and in wet sands throughout the e. half of Tex., Feb.-May; from S.C. 

 to Fla., s.e. Ark. and w. to Tex.; also e. Mex. to C.R. 



5. Callitriche Nuttallii Torr. Fig. 514. 



Fruit with pedicels of various lengths, buried in the mud at maturity, 1 mm. 

 wide, 0.6-0.8 mm. high, 0.3-0.5 mm. thick; mericarps with flat faces, the margins 

 with a thin wing that is curled toward the face to give the appearance of thickened 

 margins; stigmas about 0.8 mm. long, sometimes persistent and loosely ascending 

 or somewhat reflexed; filaments 0.2-0.5 mm. long; anthers 0.2-0.3 mm. wide; plant 

 a minute annual; leaves 3-4 mm. long, 0.5-1.5 mm. wide, oblanceolate-obovate, 

 very obscurely 3-veined. 



In damp soil in fallow fields and flats in e. Tex., Mar.-May; along Gulf Coast 

 from Ala. to Tex., inland to cen. Ala. and Ark. 



6. Callitriche terrestris Raf. emend. Torr. Fig. 513. 



Fruit 0.6-0.9 mm. wide, 0.4-0.7 mm. high, with pedicels mostly 0.2 mm. long 

 or rarely reaching 0.6 mm. long; mericarps usually equally rounded at each end 

 but rarely broadly rounded above so that the fruit becomes slightly heart-shaped; 

 faces of mericarps flat; outer edges of mericarps appearing scarcely winged but 

 under high magnification showing a very narrow wing with radii but little anasto- 

 mosing of radii; stigmas 0.2-0.4 mm. long, usually persistent and deflexed; anthers 

 0.1-0.2 mm. wide, on filaments 0.1-0.2 mm. long; a minute annual with simple to 

 much-branched slender stems to about 3.5 cm. long; leaves rather uniform, 

 obovate-oblanceolate to spatulate, 2-3.5 mm. long, 0.6-1 mm. wide, very obscurely 

 3-nerved. C. Austinii Engelm., C. defiexa A. Br. var. Austinii (Engelm.) Hegelm. 



On damp soil, moist pathways, wet open spots in lawns and other such places 

 in e. Tex. and e. Okla., Mar.-June; from N.E., s. to s.e. Va., w. Ala., La., Tex., 

 Okla., Mo. and 111. 



Fam. 80. Anacardiaceae Lindl. Sumac Family 



Trees, shrubs or vines with resin-ducts in the bark and sometimes in the herbage, 

 with a resinous or milky and usually acrid juice; leaves alternate or rarely opposite, 

 simple to 3-foliolate or pinnate, deciduous or persistent, usually essentially exstipu- 

 late; flowers numerous, small, in terminal thyrses or axillary panicles, or rarely in 

 clusters of spikes, perfect or unisexual through abortion, mostly regular with 

 5-parted (less often 3- or 4-parted) whorls; receptacle various, flat, concave or 

 convex, sometimes forming a cushionlike gynophore, developing into a ring- or 



1091 



