Genus i. 



BUCKWHEAT FAMILY. 



647 



Macounastrum. 

 Briogonum. 



Rumex, 

 Oxyria. 



Flowers or flower-clusters subtended by involucres. 



Ocreae present ; calyx 2-4-parted ; stamens 3 or fewer. 

 Ocreae none ; calyx 6-cleft or 6-parted ; stamens 9 ; achene 3-angled 

 Flowers or flower-clusters not involucrate ; stamens 4-8. 



Stigmas tufted ; sepals of the inner row usually accrescent. 

 Calyx 6-parted ; style 3-parted ; achene 3-angled. 

 Calyx 4-parted ; style 2-parted ; achene lenticular. 

 Stigmas capitate, 2-cleft or toothed ; sepals of the outer row often accrescent or^reflexed, 

 Floral tube obscurely or only slightly developed ; stigmas not 2-cleft ; ovule erect. 



Internodes of the stem and branches not adnate ; plants not heath-like ; sepals of the outer 

 row often winged . 

 Leaf-blades jointed at the base; ocreae 2-lobed, becoming lacerate; filaments, at least 



the inner, dilated. 5. Polygonum. 



Leaf-blades not jointed at the base; ocreae various, not 2-lobed; filaments slender. 

 Ocreae cylindric, truncate. 



Sepals 4 ; calyx curved ; stamens 4. 6. Tovara. 



Sepals s, if fewer, the stamens more than 5 ; calyx not curved. 7. Persicaria. 

 Ocreae oblique, more or less open on the side facing the leaf. 



Plants with fleshy rootstocks, scaly caudices and simple flower-stems ; leaves 



mostly basal ; inflorescence simple ; styles elongated. 8. Bistorta. 



Plants with fibrous roots or slender rootstocks, without scaly caudices, with 

 branching stems ; leaves not basal ; inflorescence branched. 

 Sepals neither keeled nor winged. 



Racemes collected into terminal corymbs ; embryo dividing the endosperm 



by an S-shaped curve ; plants smooth. 9. Fagopyrum. 



Racemes not in terminal corymbs; embryo slender, at one side of the 

 endosperm ; plants prickle-armed. 10. Tracaulon. 



Sepals, at least the outer ones, keeled or winged. 



Stigmas rounded capitate; styles short, erect, or none. 11. Tiniaria. 

 Stigmas dilated, toothed; styles divaricate. 12. Pleuropterus. 



Internodes of the stem and branches partially adnate ; plants heath-like ; sepals of the inner 

 row often winged. 1.3. Polygonella. 



Floral tube well developed, enclosing the achene, winged ; stigmas 2-cleft ; ovule pendulous. 

 , 14. Brunnichia. 



i. MACOUNASTRUM Small in Britt. & Brown, 111. Fl. i: 541. 1895. 

 [Koenigia L. Mant. 35. 1767. Not Konig Adans. 1763.] 

 Low glabrous annual herbs, with fibrous roots, erect or spreading simple or forked stems, 

 alternate or opposite entire leaves, funnelform membranous ocreae, and minute perfect ter- 

 minal clustered flowers, subtended by a several-leaved involucre. Calyx 2-4-parted (usually 

 3-parted), greenish-white, the segments valvate, equal; pedicels short, subtended by trans- 

 parent bracts; stamens 2 or 4, alternate with and often protruding between the calyx-seg- 

 ments; filaments short, stout; anthers ovoid. Style 2- or 3-parted; stigmas capitate; achene 

 ovoid, 3-angled or lenticular,, exceeding the persistent calyx; embryo eccentric, accumbent. 



Two or three species, the following typical one circum- 

 boreal, the others of the higher Himalayas. 



1. Macounastrum islandicum (L.) Small. 

 Macounastrum. Fig. 1582. 



Koenigia islandica L. Mant. 35* 1767. 



M. islandicum Small in Britt. & Brown, 111. Fl. 1 : 542. 

 1896. 



Stems very slender, i'-4' long, sometimes tufted. 

 Leaves obovate, oblong or almost orbicular, i"-s" long, 

 fleshy, obtuse at the apex, sessile or short-petioled ; 

 ocreae about i" long; involucre consisting of 3-6 

 obovate or orbicular leaves more or less united at their 

 bases; flowers fascicled in the involucres, short- 

 pedicelled; calyx i" long, the segments ovate-lanceolate, 

 rather obtuse ; stamens very short ; style-branches short ; 

 achene less than 1" long, brown, often slightly curved, 

 striate, its faces convex. 



Greenland and Labrador to Hudson Bay and Alaska. 

 Also in arctic Europe and Asia. Summer. 



2. ERIOGONUM Michx. Fl. Bor. Am. i : 246. 1803. 



Annual or perennial acaulescent or leafy-stemmed herbs, some species very woody at 

 the base, with simple or branched, often tufted stems, and entire alternate opposite or 

 whorled leaves. Flowers small, fascicled, cymose, umbellate or capitate, subtended by 

 5-8-toothed or cleft campanulafe top-shaped or almost cylindric involucres. Calyx 6-cleft 

 or 6-parted, usually colored, the segments equal or the outer ones larger. Stamens 9, 

 included or exserted; filaments filiform, often villous. Style 3-parted; stigmas capitate. 

 Achene pyramidal, 3-angled, more or less swollen near the base, invested by the calyx- 

 segments, or winged. Embryo axial or somewhat eccentric. [Greek, referring to the woolly 

 and jointed stems.] 



