small tight head of white or pale-pink flowers on a very long peduncle longer than 

 leaves); calyx 5-parted; stamens 8; achene triquetrous, 3-3.5 mm. long, black or 

 brownish, smooth. Tracaulon sagittatum (L.) Small. 



Infrequent at margins of lakes, swamps, marshes and bogs in e. Tex., and Okla. 

 (McCurtain and Haskell cos.), June-Oct.; Nfld. to Sask., s. to Fla. and Tex. 



3. Polygonum Convolvulus L. Black bindweed. 



Annual vine, glabrous but minutely scurfy; stems twining, 1-12 dm. long; leaf 

 blades ovate-deltoid or usually ovate-sagittate, 15-60 mm. long, acuminate; flowers 

 borne usually in pairs or threes at the same nodes or toward the ends of the 

 branches, flowers in racemelike inflorescences; pedicels very slender, 2-3 mm. long, 

 reflexed; calyx after anthesis becoming about 3.5 mm. long, closely investing the 

 achene, the 3 outer sepals minutely keeled; achene 3.5-4 mm. long, triquetrous, 

 black. Bilderdykia Convolvulus (L.) Dum., Tiniaria Convolvulus (L.) Webb & 

 Moq.. Reynoutria Convolvulus (L.) Shinners. 



On mud at edge of lakes, streams and ponds, on wet sand-gravel bars along 

 streams and in seepage about springs, commonly in disturbed soil and often in 

 gardens and flowerbeds, nearly throughout Tex., except extreme Trans-Pecos, 

 Okla. {Waterfall), N.M. (widespread), and Ariz. (Apache, Navajo and Coconino, 

 s. to Cochise and Pima cos.), Apr.-Sept.; a Eur. weed now widely adv. 



4. Polygonum cristatum Engelm. & Gray. 



Short-lived perennial vine (flowering first year); stems annual, twining; leaf 

 blades deltoid to shallowly sagittate-deltoid, 2-9 cm. long, only very slightly 

 (if at all) acuminate; flowers reflexed (pendulous) on very slender pedicels 

 several mm. long, at the middle nodes borne in twos or threes but on some of the 

 distal parts of the stems borne in racemelike masses; calyx after anthesis eventually 

 about 6 mm. long. 3 of the sepals with flat, toothed or crimped wings 0.25-1 mm. 

 broad; achenes lustrous, trigonous, 3-3.5 mm. long. Tiniaria cristata (Engelm & 

 Gray) Small, Bilderdykia cristata (Engelm. & Gray) Greene, P. scandens L. var. 

 cristatum (Engelm. & Gray) Gl., Reynoutria scandens (L.) Shinners var. 

 cristatum (Engelm. & Gray) Shinners. 



Edges of woods, creek bottoms, wet gravel bars along rivers, in e. and n.-cen. 

 Tex. (possibly also canyons in Plains Country), e. Okla. (McCurtain and Chero- 

 kee COS.), Aug-Oct.; Tex., Ark., Okla. and La.; sparingly elsewhere where 

 probably adv. 



5. Polygonum texense M. C. Johnst. 



Perennial herb to 6 dm. tall, each shoot from a short reddish-brown fibrous 

 (from ocreae remnants) caudex 2-3 (-10) mm. thick, usually (perhaps always) 

 with brown rhizomes 2-3 mm. thick and with internodes to 4 cm. long; aerial 

 shoots with solitary ascending stems 1-2 mm. thick from each crown, with some 

 ascending branches at irregular intervals but usually unbranched in their distal 

 halves or thirds; leaf blades of the innovations (emerging in April) lanceolate, 

 15-24 mm. long, 4-7 mm. broad, green, flat, without conspicuous nervation, 

 blunt at apex, narrowed and with an abscission joint at base, falling by May; 

 petiole about 2 mm. long, inconspicuous and appearing as part of the ocrea; 

 ocreae 6-1 1 mm. long; lower part of ocrea strongly nerved and clasping the 

 petiole, the upper part hyaline (except for the nerves) and with 3 acute lobes, 

 eventually becoming shredded into fibers and lost; uppermost leaves reduced to 

 bracts with subpersistent blades 2-10 mm. long, those of the upper 2 to 10 cm. 

 of stem usually less than 4 mm. long and quite inconspicuous; flowers solitary or 

 in 2's or 3's at the upper nodes, erect or somewhat nodding; pedicels filiform, 

 about 2 mm. long, almost all included in the lower part of the ocreolae; calyx 



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