BUCKWHEAT FAMILY 233 



Fruit erect. 



Inflorescence of small axillary clusters scattered more or less thoroughout the plant- 

 all except P. minimum with elongated stems or branches; perianth-lobes never 

 keeled near the apex. 

 Plants copiously leafy throughout; upper leaves scarcely reduced and more 



crowded. 



Very slender and low annuals, with red wiry, terete, non-striate stems. 



1. P. minimum. 

 Stouter and larger plants, often perennial, with prominently striate stems 



usually 38 dm. long. 

 Perianth-lobes with yellowish green margins; plant erect, with spreading 



branches in age; leaves broad, yellowish green. 2. P. erectum. 

 Perianth-lobes with white, pink or purplish margins; plant prostrate or 



diffusely spreading; leaves from bright to pale bluish green. 

 Leaves thick, prominently veined, oblong, oval, or spatulate, obtuse or 

 rounded at the apex, usually pale; ocreae very conspicuous; 

 faces of the achenes granular. 3. P. buxiforme. 



Leaves thin, not prominently veined, bright green ; ocreae not conspicu- 

 ous; faces of the achenes finely striate. 

 Perianth 2.5-3.5 mm. long; achenes 2.5-3 mm. long, acute; leaves 



2-4 cm. long. 4. P. aviculare. 



Perianth 2-2.5 mm. long; achenes 2-2.5 mm. long, acuminate; leaves 



mostly less than 2 cm. long. 5. P. neglectum. 



Plants with the upper leaves more scattered and reduced; mostly erect perennials. 

 Upper bracts not subulate; achenes mostly dull. 



Lobes of the perianth with yellowish margins; perianth 3-4 mm. long; 



achenes about 3 mm. long, nearly smooth. 6. P. ramosissimum. 



Lobes of the perianth with whitish or pinkish margins; perianth 2-3 mm. 



long; achenes 2-2.5 mm. long, distinctly granulate or striate. 

 Plant copiously branched and broom-like; leaf-blades linear or nearly 



so; achenes granulate. 7. P. prolificum. 



Plant sparingly branched, mostly below; leaf-blades oblanceolate to 



elliptic; achenes finely striate. 8. P. rubescens. 



Upper bracts subulate; achenes smooth and shining. 9. P. sawatchense. 



Inflorescence aggregate at the ends of the branches, or more scattered in P. parony- 

 chioides, in which, however, some of the perianth-lobes are keeled near the 

 apex ; bracts leaf-like and usually broader than the narrowly linear leaves ; plants 

 dwarf annuals. 

 Perianth-lobes not keeled. 



Leaves several, gradually merging into the bracts; achenes blunt-angled and 



strongly striate. 10. P. Watsonii. 



Leaf usually solitary and much longer than the bracts: achenes sharp-angled 



and obscurely striate. 11. P. uni folium. 



Some of the perianth-lobes keeled near the apex. 



Bracts herbaceous or the uppermost with a very narrow scarious margin. 

 Bracts linear; ocreae conspicuous; inflorescence interrupted. 



12. P. paronychioides. 



Bracts oblong or narrowly oblong; ocreae inconspicuous; inflorescence con- 

 tiguous and dense. 13. P. Kelloggii. 

 Bracts with broad white petaloid margins. 14. P. polygaloides. 

 Fruit reflexed. 



Upper bracts much reduced and subulate. 



Perianth 1.5-2.5 mm. long; leaves narrowly linear. 15. P. Engelmannii. 



Perianth 3-5 mm. long. 



Outer perianth-lobes oblong, obtusish, thickened and green or purplish on the 

 back; lower leaves oblanceolate to linear-oblanceolate. 



16. P. Douglasii. 

 Outer perianth-lobes obovate, rounded at the apex, merely with a narrow 



midrib; lower leaves linear. 

 Inflorescence long, lax, virgate; ocreae of the bracts inconspicuous. 



17. P. majus. 

 Inflorescence dense, crowded at the ends of the branches; ocreae of the 



bracts contiguous and conspicuous. 18. P. spergulari forme. 



Upper bracts foliaceous, relatively broad lanceolate or oblong. 

 Perianth 3.5-4 mm. long; lower leaves oblong or nearly so. 



Achenes included. 19. P. montanum. 



Achenes exserted. 20. P. commixtum. 



Perianth 2-2.5 mm. long; lower leaves obovate, very acute. 



21. P. Austinae. 



1. P. minimum S. Wats. Annual; stem erect or spreading, 3-20 cm., 

 rarely 30 cm. high, branched mostly at the base; leaves obovate, sometimes 

 ovate or elliptic, 0.5-2 cm. long, evenly distributed or crowded above; perianth- 

 segments 1.5-2 mm. long, greenish with rose-colored margins; achenes 2-2.3 

 mm. long, smooth and shining. P. Torreyi S. Wats. Dry or sandy slopes: 

 B.C. Mont. Colo. Calif. Submont. Jl-S. 



2. P. erectum L. Annual; stem usually erect, 2-6 dm. high, yellowish 

 green; leaves oval, elliptic or obovate, 1-6 cm. long; flowers in small axillary 



