234 POLYGONACEAE 



clusters; perianth 3 mm. long; achenes dark brown, granular and dull. Waste 

 places: Me. Ga. Ark. N.M. Alta.; (? Ida.) Plain. Je-S. 



3. P. buxiforme Small. Annual OIT perennial; stem usually prostrate, 3-12 

 dm. long; leaves oblong, elliptic or oblanceolate, 0.5-2.5 cm. long, usually ob- 

 tuse, often crisp on the margin; perianth 2-2.5 mm. long; achenes 2-2.5 mm. 

 long, dark brown, mostly dull, granular. Sandy or alkaline soil: Ont. Va. 

 Tex. Nev. B.C. Plain Mont. Je-S. 



4. P. aviculare L. Annual or sometimes perennial; leaves oblong-lanceolate, 

 acute at both ends, petioled, dall bluish green, rather thin, 1-3 cm. long; flowers 

 pedicelled; perianth 2.5-3.5 mm. long; achenes dark, rugulose-striate, dull. Waste 

 places: Newf. Va. Calif. B.C. ; nat. or adv. from Eu. Plain Submont. My-O. 



5. P. neglectum Besser. Annual or perennial; stems with short internodes, 

 strongly striate, usually minutely roughened; leaves firm, narrowly elliptic- 

 lanceolate, or the upper rarely linear; margins often revolute when dry; perianth 

 2-2.5 mm. long, venose; segments with usually purplish margins; achenes reddish 

 brown, apiculate-acuminate. P. aviculare angustissimum Meisn. Waste places: 

 Me. Fla. Ark. N.M. Alta.; nat. or adv. from Eu.; more common than 

 P. aviculare. Plain 'Submont. JeN. 



6. P. ramosissimum Michx. Annual; stem 2-10 dm. high, somewhat 

 virgate, yellowish green; leaves lanceolate, oblong, or linear-oblong, 1-4 cm. long, 

 yellowish green, the upper ones much reduced in size; perianth about 3 mm. long; 

 achenes 3 mm. long, black, not shining. River valleys and sandy soil: Man. 

 Ills. N.M. Nev. Wash. B.C. Plain Mont. Jl-S. 



7. P. prolificum (Small) B. L. Robins. Annual; stem 3-5 dm. high, much 

 branched, strongly striate, dark green or reddish; leaves linear-oblong or linear, 

 thick, obtuse or acute, strongly veined beneath, dark green, 1-2 cm. long; peri- 

 anth about 2 mm. long; achenes brown, 2 mm. long, concave on the lanceolate- 

 deltoid faces, shining. (?) P. flexile Greene. Sandy places: Me. Va. Colo. 

 Mont. Plain. Jl-O. 



8. P, rubescens Small. Annual or perennial; stem erect, ultimately 

 branched, 1-5 dm. high; leaves thick, narrowly oblong or elliptic, 1-2.5 cm. long, 

 the upper reduced; perianth 3 mm. long; achenes 2-2.5 mm. long, dull. Sandy 

 soil: Sask. Colo. Nev. Ida. Plain Submont. Je-S. 



9. P. sawatchense Small. Annual; stems erect, striate, obscurely 4-angled, 

 branched from the base, 5-30 cm. high; lower leaves oblanceolate, 1-2 cm. long, 

 acute or obtuse at the apex, often more or less revolute, with a prominent mid- 

 vein; perianth-segments green, only slightly lighter on the margins, 2 mm. long; 

 achenes rather blunt at both ends, smooth and glossy. Hillsides and mountains: 

 S.D.N.M. Calif. Wash. Submont. Mont. Jl-Au. 



10. P. Watsonii Small. Annual; stem erect, 5-15 cm. high, sparingly 

 branched, 4-angled, glabrous; leaves linear, 1-5 cm. long; bracts reduced, 0.5-1 

 cm. long, linear-lanceolate; perianth-segments green, pinkish on the margins, 2 

 mm. long; achenes nearly black, narrowly ovoid, strongly striate. P. imbricatum 

 Nutt., not Raf. P. confertiflorum Nutt. Wet places: B.C. Sask. N.M. 

 Calif. Plain Mont. Je-Au. 



11. P. unifolium Small. Annual, dwarf; stem 1-3 cm. high, simple, or 

 nearly so; well developed leaf mostly solitary, linear, erect, 7-10 mm. long; bracts 

 several, crowded, imbricate, linear or linear-lanceolate; perianth-segments about 

 1.5 mm. long, white or pinkish, with green ribs; achenes about 1.3 mm. long, 

 shining, included. Wet places: Mont. 'Colo. Utah. Plain Mont. Jl-Au. 



12. P. paronychioides Small. Annual, bushy; stem copiously branched at 

 the base, 8-15 cm. long; leaves linear, 8-10 mm. long; perianths short-pedicelled, 

 solitary or a few together in the axils; segments green, with pale or pink margins, 

 becoming fully 2 mm. long; lobes slightly keeled, acutish; achenes rhombic, 

 about 2 mm. long, granular. Wet places: Mont. Wyo. Submont. Au. 



13. P. Kelloggii Greene. Annual; stem erect, 3-8 cm. high, branched at 

 the base; leaves linear, acute, 5-10 cm. long, spreading; perianth-segments 1.5-2 



