344 POLYGON ACEjE. [Polygonum. 



Section 1. Bistor'ta, Tournef. Rootstoch perennial. Stem simple, 

 erect. Stipules truncate. Racemes solitary, spike-like ; pedicels jointed 

 at the top. Stamens 8. Fruit 3-quetrous ; embryo lateral, cotyledons 

 thin liat. 



1. P. Bistor'ta, L. ; leaves obtuse or cordate at the base, petiole 

 winged, raceme dense cylindric. B-istort, Snake-root. 



Wet meadows, wild from Renfrew and Edinburgh southd., often introduced 

 N. of it ; ascends to 1,050 ft. in Derby ; Ireland, rare, native ?; fl. June— Sept. — 

 Glabrous, except the leaf -nerves beneath. Rootstock woody, twisted, creep- 

 ing ; roots tuberous. Stem 1-2 ft., strict, slender. Leaves, radical 3-6 in., 

 oblong-ovate, obtuse, waved, glaucous beneath ; petiole 6-12 in., broadly 

 winged above; cauline subsessile, broader at the base; stipules £-3 in. 

 Raceme 1^-2 in. ; bracts cuspidate. Flowers } in. long, white or pink, 

 honeyed, proterandrous. Stamens exserted. Fruit brown, shining. — Distrib. 

 Europe (Arctic), N. and W. Asia, Himalaya. — Rootstock astringent ; used 

 as food in famine-times, and formerly medicinally. 



2. P. vivip'arum, L. ; leaves narrowed at the base, petiole not winged, 

 raceme spike-like bulbiferous below. 



Mountain pastures and wet alpine rocks ; from Carnarvon and York to Shet- 

 land ; asjends to 4,000 ft. ; W. Ireland ; fl. June- Aug.— Glabrous. Rootstock 

 slender. Stem 4-16 in., slender. Leaves 1-2^ in., £-£ in. broad, radical 

 mrrow linear-oblong, petiole as long or shorter, subacute, glaucous beneath, 

 margins revolute ; cauline few, shorter petioled ; stipules |-1§ in. Racemes 

 1-3 in., slender, obtuse. Flowers white or pink, polygamous ; bulbils purple. 

 Fruit rarely ripening. — Distrib. Alps of N. temp, and Arctic regions. 



Section 2. Persica'ria, Meissn. Rarely perennial. Stipules truncate, 

 subentire. Racemes spike-like ; pedicels jointed at the top. Stamens 

 4-8. Fruit compressed or 3-quetrous ; embryo lateral, cotyledons thin, 

 flat. 



* Spikes short, usually dense, not or rarely interrupted, not leafy at the base. 



3. P. amphib ium, L. ; perennial, creeping or floating, leaves oblong 

 or lanceolate, racemes subsolitary dense-fld., peduncles hairy, sepals 

 eglandular, stamens 5, styles 2 united half way, fruit ovoid, faces convex. 



Damp and watery places, N. to Shetland ; Ireland ; Channel Islands ; fl. July- 

 Aug. — Rootstock creepiug, slender, woody, branched. Stem very variable in 

 length. Leaves floating and long-petioled or aerial and subsessile, obtuse or 

 acute, serrulate or ciliate, eglandular ; stipules large, appressed, glabrous or 

 hispid, mouth entire. Racemes 1-3, ^-2 in. ; peduncle stout ; pedicels short ; 

 bracts obtuse acute or cuspidate. Sepals | in., not nerved, pale or bright 

 rose-red, much longer than the shining fruit. — Distrib. N. temp, and 

 Arctic regions. 



4. P. lapathifo'lium, L. ; annual, leaves ovate or oblong-lancolate, 

 racemes subcylindric, peduncle rough and sepals glandular, stamens 5-6, 

 styles 2 free, fruit orbicular, faces concave. 



