308 POLYGONS^. [Poi.yunM M. 



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



raceme spike-like bulbiferous below. 



Mountain pastures and wet alpine rocks ; ascending to 4,000 ft. in Scotland ; 

 N.W. of Ireland, very rare ; fl. June-Aug. Glabrous. Rootstock slender. 

 Stem 4-16 in., slender. Leaves l-2 in., -|j in. broad, radical narrow linear- 

 oblong, petioles as long or shorteV, subacute, glaucous beneath, margins 

 revolute ; cauline few, shorter petioled ; stipules ^-1J in. #/'/.? 1-3 in., 

 slender, obtuse. Flowers whitish or pink, as in P. Sigtorta, but rather 

 smaller ; bulbils purple. Fruit rarely ripening. DISTRIB. Alps of N. temp. 

 and high Arctic regions. 



SECTION 2. Persica'ria, Meissn. Annual, rarely perennial. 

 truncate, entire. Racemex spike-like, solitary in pairs or panicled ; pedi- 

 cels 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, spikes dense, 

 peduncles hairy, sepals eglandular, stamens 5, styles 2 united half-way, 

 fruit ovoid, faces convex. 



Damp and watery places ; fl. July-Aug. Rootstock creeping, slender, woody, 

 branched. Stem very variable in length and height. Leaven oblong linear- 

 oblong or lanceolate, obtuse or acute, serrulate or ciliate, eglandular, 

 petioled or not ; stipules large, appressed, mouth entire. Spikes 1-3, ^-2 in. ; 

 peduncles stout, hairy ; pedicels short ; bracts obtuse acute or cuspidate. 

 Sepals J in., not nerved, pale or bright rose-red, much longer than the shining 

 fruit. DISTRIB. N. temp, and Arctic regions. 



VAR. 1, aquat'icu.m ; leaves floating long petioled, like those of Pot<tnH/-tn/i 

 natnns, and stipules glabrous. VAR. 2, ten-fJtre ; terrestrial, leaves shortly 

 petioled or sessile longer and narrower, and stipules scabrid or hispid. 



4. P. lapathifo'lium, L. ; annual, spikes subcylindric, peduncle rough 

 sepals glandular, stamens 6, styles 2 free, fruit orbicular, faces concave. 

 Fields and waste places ; ascends to near 1,000ft. in Yorkshire ; fl. July-Aug. 



Stem 1-4 ft., decumbent and rooting below, much branched ; nodes stout, 

 swollen. Leaves 4-6 in., shortly petioled, ovate- or oblong-lanceolate, acumi- 

 nate, ciliate, glabrous pubescent scaberulous or cottony above and below, 

 sometimes glaucous below, or with a black blotch above, punctate and 

 sparingly glandular ; stipules loose, often ciliate. Spikes 1-3, f-l in., 

 often racemed or panicled, obtuse, stout ; bracts broad, obtuse or cuspidate. 

 Sepals nerved, equalling the obtuse dark fruit. DISTRIB. Europe, N. Africa, 

 Siberia, Dahuria. \V. Asia to India; introd. in America. 



VAR. 1, lapathlfo'fitim. proper ; upper stipules obliquely truncate ciliate, lower 

 naked, spikes dense remote when young, sepals greenish-white. VAR. 2, 

 nodo'sum, Pers. (sp.) ; stipules all ciliate, upper strongly, spikes drooping 

 crowded when young, sepals pink, fruit smaller. P. laxum, Reich. Rare. 



5. P. Persica'ria, L. ; annual, spikes usually short dense, peduncle 

 glabrous sepals nearly pglandiihir, stamens 6, styles 2-3 united half-way, 

 fruit plano-convex or 3-gonous. Pcrsicaria. 



Waste moist places, fields, &c.; ascending to 1,200ft. in the N. of England ; 

 fl. Julv-Oct. Stem 6-18 in., branched, erect or ascending, nodes swollen. 

 Leaves subsessile, ovate or lanceolate, subacute, ciliolate, often with a black 



