anthers, glabrous, somewhat dilated at base; fruiting heads depressed-globose; 

 achenes obovate, 2-3 mm. long, winged, the lateral ribs irregularly thickened and 

 winged or tubercled, curved to orbicular in outline, the style beak short and erect, 

 occasionally pushed in a lateral direction as the achene matures. 



In shallow water of irrigation ditches and rice fields in Ariz, and N. M., 

 Apr.-Nov.; also Calif, and n. Mex. 



Closely related to S. longiloba, with which it apparently intergrades, or more 

 likely, with which it is probably conspecific. We are in agreement with Mason, 

 however, who chose to maintain these two concepts until further field studies 

 can be made. 



10. Sagsttaria brevirostra Mack. & Bush. Fig. 68. 



Leaves erect; leaf blades broadly ovate to lanceolate, obtuse to acute at 

 apex, sagittate, the portion above the basal lobes to 2 dm. long and usually 

 about as wide, the ovate to ovate-lanceolate and acute basal lobes about equaling 

 the body of the blade; scapes simple or branched at base, the main axis with 

 as many as 12 whorls, the lower 2 to 6 whorls pistillate with pedicels to 2 cm. 

 long, the staminate with slightly longer pedicels; bracts firm, lanceolate, long- 

 attenuate, to 25 mm. long; stamens with slender glabrous filaments about as 

 long as the anthers; fruiting heads depressed, not noticeably echinate, to 2 cm. 

 in diameter; achenes cuneate-obovate to quadrate, to 3 mm. long and 2 mm. 

 wide, with an often dentate or serrate dorsal keel and usually with a narrow 

 facial ridge; beak broad-based, obliquely ascending, to 1.5 mm. long, terminating 

 the straight ventral margin. S. Engelmanniana J. G. Sm. subsp. brevirostra (Mack. 

 & Bush) Bogin. 



Along rivers, ditches and sloughs in cen. Tex. to Okla. and n. N. M. (Taos 

 Co.), June-Aug.; O and Mich., w. to S.D. and s. to Tex. and N. M. 



11. Sagittaria cuneata Sheld. Fig. 69. 



Leaves erect or erect-spreading; leaf blades broadly ovate to ovate-triangular, 

 obtuse to acute at apex, sagittate, the portion above the basal lobes to 15 cm. 

 long and 1 dm. wide, the deltoid basal lobes somewhat smaller than the body 

 of the blade; scapes erect or arching, simple or sometimes branched, the main 

 axis with as many as 7 whorls, the lower 1 or 2 (or sometimes all) whorls 

 pistillate and subsessile or on pedicels to 2 cm. long, the staminate pedicels 

 somewhat longer; bracts narrowly ovate to lanceolate, acute to attenuate, usually 

 connate at base, to 2 cm. long; stamens with glabrous subulate filaments that 

 about equal the anthers; fruiting heads to 15 mm. in diameter; achenes obovate, 

 to 2.5 mm. long and 2 mm. wide, the wide dorsal keel rounded, the faces usually 

 with a low narrow ridge; beak subulate, usually recurved, erect to suberect, 

 to 0.4 mm. long, terminating the strongly rounded ventral keel. S. arifolia Nutt. 

 ex J. G. Sm. 



Along rivers and streams in the Tex. High Plains, Okla., N.M. and Ariz., 

 June-Sept.; n.e. Can., s. to N.E., N.Y., O., Ind., 111., la., Kan., Tex., N.M., 

 Ariz, and Calif. 



Fam. 22. Butomaceae Rich. Flowering-rush Family 



Perennial aquatic or marsh herbs with stout short or elongate rhizomes and 

 usually with milky juice; leaves cauline or basal; flowers perfect in involucrate 

 umbels or solitary; sepals 3, persistent; petals 3, showy; stamens 6 to many, 

 free, the outer ones usually sterile; anthers basifixed, 2-celled, laterally dehiscent; 

 pistils 4 to 8, free or basally coherent, with numerous ovules attached over the 

 inner surface; fruit a many-seeded follicle, dehiscing on the inner side; seeds 

 without endosperm. 



153 



