418 polygonAcEjE 



and in rich soil often growing nearly erect j leaves lanceolate, with 

 chaffy stipules ; flowers minute, axillary, pink or greenish-white. 

 — Waste ground and roadsides ; abundant. — Fl. May — October. 

 Annual. 



4. P. Roberti (Ray's Knot-grass). — Intermediate between the 

 preceding and following species, resembling the former in habit, 

 the latter in fruit. It has long, straggling, prostrate stems ; lan- 

 ceolate-elliptical, flat leaves which bend towards the stem and are 

 often glaucous ; and a large, smooth, shining nut which is longer 

 than the perianth. — Sandy sea-shores ; not uncommon. — Fl. 

 August, September. Annual or perennial. 



5. P. maritimum (Sea-side Knot-grass). — An allied, but more 

 shrubby species, with prostrate, often much buried, stiff, and 

 woody stem ; fleshy leaves with revolute edges, diverging from the 

 stem, netted with veins and often glaucous beneath. — Sandy sea- 

 shores in the south-west of England; very rare. — Fl. July — 

 September. Perennial. 



*** Leaves with or without a dark spot in the centre ; flowers in 

 spikes ; stamens 4 — 8 ; styles 2 — 3 ; nut compressed or 3-sided 



6. P. Hydropiper (Water Pepper, Biting Persicaria). — A very 

 acrid plant, creeping and rooting at the base, 1 — 3 feet high, 

 much branched, with lanceolate, tapering, wavy leaves, and well 

 distinguished by its slender, drooping, loose spikes of greenish 

 flowers ; stamens 6. — Ditches and places where water has stood 

 during winter ; abundant. The fresh juice, though acrid, is of a 

 not unpleasant flavour, and is said to cure pimples on the tongue. 

 — Fl. August, September. Annual. 



7. P. minus (Creeping Persicaria). — A much smaller and more 

 slender species than the last, much branched, erect, or prostrate 

 with ascending branches ; leaves linear-lanceolate, flat, with fringed 

 stipules close to the stem ; very slender, erect spikes of flowers 

 which are only half the size of those of P. Hydropiper ; styles 

 2 — 3, united for at least half their length. — Wet, gravelly 

 places ; not uncommon. — Fl. August, September. Annual. 



8. P. mite (Lax-flowered Persicaria). — Stem creeping and 

 rooting below, 1 — 3 feet high, branched, slender ; leaves lanceo- 

 late, wavy, with loose, funnel-shaped, much fringed stipules ; 

 flowers in erect, slender, interrupted spikes; stamens 5 — 6 ; 

 styles 2 — 3, united for half their length ; nut black, roughish, 

 compressed. — Wet places; local. — Fl. June — September. An- 

 nual. 



9. P. Persicaria (Common Persicaria). — A common weed, 

 1 — 2 feet high, erect or ascending, usually swollen at the nodes, 



