BUCKWHEAT FAMILY 55 



I. AviCULARIA 

 Suffrutescent perennials; leaves articulate at the junction with the stipule-sheath. 



Midrib of leaf prominent with a 2-winged keel; style 3-cleft to above the middle; maritime 



Midrib of leaf not prominent or keeled; style 3-parted to the base; alpine species. 2. P. shastense. 

 Annuals, except P. Fowleri. 

 Stems terete or nearly so. 



Achenes conspicuously exserted. 



Prostrate maritime perennial; achene broadly ovoid. 3. P. Fowleri. 



Erect annual; achene narrowly ovoid. 4. P. exsertum. 



Achenes nearly or quite included. 



Calyx-lobes with white or pink margins; 2 mm. or less in length. 



Achenes striate; flowers borne in the axils of leaves little reduced; plants mostly prostrate 



or ascending. s - p - avtculare. 



Achenes smooth and shining; flowers borne in the axils of much reduced leaves, appearing 

 spicate. 6 - P - argyrocoleon. 



Calyx-lobes with yellowish margins and green midrib, 2.5-3 mm. long. 



Leaves elliptic, obtuse. 7. P. erectum. 



Leaves lanceolate, acute. 8. P. ramosissimum. 



Stems rather sharply angled at least toward the ends of the branches, less so in minimum. 

 Fruit deflexed on recurved pedicels. 



Achenes oblong; calyx 3-5 mm. long. 



Calyx 4-5 mm. long. 9. P. majus. 



Calyx 3 mm. long. 10. P. Douglasii. 



Achenes ovoid; calyx 2 mm. long. 11. P. Austiniae. 



Fruit remaining erect, the pedicels not becoming recurved. 



Flowers in small axillary clusters, distributed along more or less the length of the branches. 



Stems rather obscurely angled; leaves ovate to oblong-ovate, not markedly reduced above. 



12. P. minimum. 



Stems distinctly angled; leaves oblanceolate, the upper much reduced. 



13. P. sawatchense. 

 Flowers in interrupted or spicate terminal racemes. 



Spikes mostly interrupted, sometimes congested in spergulariaeforme. 



Calyx 3 mm. long; styles 3-parted to the middle; filaments not broadly dilated at base. 



14. P. spergulariaeforme. 



Calyx 2 mm. long; styles 3-parted to the base; filaments broadly dilated at base. 



15. P. Nuttallii. 

 Spikes congested and mostly continuous. 



Achenes brown, smooth; bracts linear, similar to the leaves and little reduced; stigmas 



sessile or subsessile on the ovary. 16. P. Kelloggii. 



Achenes black, striately roughened; style evident, cleft to below the middle. 



Bracts oblong, conspicuously white-margined. 17. P. polygaloides. 



Bracts linear-lanceolate, not white-margined. 18. P. confertiflorum. 



II. DUVARIA 

 Perennial with a branched woody rootstock. 19. P. Bolanderi. 



Annual. 



Stipule-sheaths conspicuously and deeply lacerate into several to many bristle-like segments. 



Segments of the sheath several, subulate and rather firm. 20. P. californicum. 



Segments of the sheath numerous, finely capillary and weak or cottony. 21. P. Parryi. 



Stipule-sheaths split into two oblong-ovate segments, these sharply serrate at apex. 



22. P. Bidwelliae. 



III. BlSTORTA 



Racemes narrowly cylindric; achenes granular and dull; basal leaves usually cordate cr subcordate at base. 



23. P. viviparuin. 

 Racemes oblong; achenes smooth and shining; basal leaves acuminate at base. 24. P. bistortoides. 



IV. ACONOGONUM 

 Flowers in leafless or nearly leafless panicles. 25. P. Phytolacca^ 'folium. 



Flowers in 2— 4-flowered axillary clusters. 



Leaves soft-pubescent, short-petioled; achene obovoid. 26. P. Newberryi. 



Leaves sessile, more or less scabrous; achene ovoid. 27. P. Davisiae. 



V. Persicaria 



Perennials. 



Spikes solitary, rarely in pairs; stamens 5; flowers rose-red; stipule-sheaths not bristly-ciliate. 



Peduncles glabrous or nearly so; spikes ovoid or oblong, mostly 15-25 mm. long. 



28. P. natans. 



Peduncles glandular-hispid; spikes cylindric, 3-10 cm. long. 29. P. coccinium. 



Spikes several to many, paniculate; stamens 8; stipule-sheaths bristly-ciliate. 



Calyx not glandular-punctate; stipule-sheaths hairy. 30. P. hydropiperoides. 



Calyx glandular-punctate. 



Achenes dull. 31. P. Hydropiper. 



Achenes shining. 32. P. punctatum. 



Annuals; spikes paniculate; stamens usually 6. 



Stipule-sheaths bristly-ciliate. 33. P. Persicaria. 



Stipule-sheaths naked or very short-glandular-ciliolate. 



Achenes suborbicular, 2.5-2.9 mm. broad; peduncles stipitate-glandular. 34. P. pennsylvanicum. 



Achenes ovate, 1.5-2 mm. long; peduncles glabrous or slightly glandular. 35. P. lapathifolium. 



VI. BlLDERDYKIA 

 Twining or trailing annual; leaves cordate. 36. P. Convolvulus. 



