FLORA OF THE DISTRICT OF COLUMBIA. 147 



1. Bilderdykia convolvulus (L.) Dura. Bindweed. 

 Waste and cultivated ground; common weed. Summer. Natiu-alized from Eur.; 



nearly throughout N. Amer. {Polygonum convolvulus L.; Tiniaria convolvulus 

 Webb & Moq.) 



2. Bilderdykia scandens (L.) Greene. 



Thickets and brushy fields; abundant. July-Sept. Eastern N. Amer. {Poly- 

 gonum scandens L.; Tiniaria scandens Small.) 



Polygonum cristatum Engelm. & Gray is a form of this species with incised sepal 

 wings. It has been collected at several localities within our range. 



6. PLEUROPTERUS Turcz. 



1. Pleuropterus zuccarinii Small. Japanese knotweed. 



Escaped from cultivation at several localities. July-Oct. Native of Japan; escaped 

 locally in the northeastern U. S. {Polygonum cuspidatum Sieb. & Zucc.) 



7. TRACAULON Raf. Tear-thumb. 



Stems sharply 4-angled; leaves short-petioled, the blades arrow-shaped; style 3- 

 parted; achene sharply 3-angled 1. T. sagittatum. 



Stems ridged; leaves mostly long-petioled, the blades halberd-sha'ped ; style 2-parted; 

 achene lenticular 2. T. ariiolium. 



1. Tracaulon sagittatum (L.) Small. 



Swamps, wet thickets, and stream banks; common. Aug. -Sept. Eastern N. 

 Amer. {Polygonum sagittatum L.) 



2. Tracaulon arifolium (L.) "af. 



Low woods or borders of woods; not very common. Aug.-Sept. Eastern N. 

 Amer. {Polygonum arifolium L.) 



8. FAGOPYRUM Gaertn. Buckwheat. 



1. Fagopyrum esculentum Moench. 



Dumps and waste places; occasional. Summer. Cultivated in N. Amer.; 

 sometimes escaping. {Fagopyrum fagopyrum Karst.) 



46. CHESrOPODIACEAE. Goosefoot Family. 



Leaves linear, pungent-tipped; plants neither mealy nor glandular 3. SALSOLA. 



Leaves broader than linear, not pungent-tipped; plants glandular or more or less 

 white-mealy. 

 Fruit inclosed in a regular toothed calyx; leaves all alternate; flowers all alike. 



1. CHENOPODITJM. 



Fruit inclosed by 2 nearly distinct triangular green bracts; lower leaves opposite; 



flowers of 2 kinds, stamlnate and pistillate 2. ATRIPLEX. 



1. CHENOPODITIM L. 



Plants with a strong disagreeable odor, even when dry, more or less glandular; leaves 



bright green; flower clusters in slender spikes 1. C. ambrosioides. 



Plants without a strong odor, never glandular; flower clusters not in slender spikes. 

 Outer coat of the fruit easily separated from the seed, the latter shining; plants 

 slender, usually found in woods. Leaves bright green, thin, entire or toothed 



near the base 2. C. boscianum. 



. Outer coat of the fruit firmly attached to the seed and not easily separated from it 

 by rubbing; plants usually stout and frequenting waste or cultivated ground. 

 Inflorescence usually shorter than the leaves, comparatively few-flowered; leaves 

 green, not at all mealj'-, sMning on the upper surface 3. C. murale , 



