POLYGONACE^., 77 



ably larger than in P. Persicaria, about J inch long, and doubly 

 concave ; the perianth strongly veined with hooked veins, and is usually 

 of a dull greenish white, more rarely slightly tinged with rose colour. 

 The styles are distinct for a greater part of their length, and are longer 

 than those of P. Persicaria. The leaves are generally marked with a 

 black blotch, and are very often clothed with short cottony hairs 

 beneath, and scattered ones above; the nerves on the under side 

 strigosely hairy. Mr. Watson found a curious form in Guernsey with 

 the leaves nearly as broad as long. 



Yar. 3 has very much the aspect of the var. elatum of P. Persicaria, 

 but is always readily distinguishable by the conspicuous glands on the 

 peduncles, pedicels, j^erianth, and leaves, except when the latter are 

 clothed with white woolly hair beneath, in which case the glands are 

 not visible. The perianth also is more strongly veined, and the nut is 

 broader, shorter, and concave on each face. None of the flow^ers, so 

 far as I have seen, have 3 styles, and consequently there are no 3-sided 

 nuts. I do not see how it can be separated from var. a, even as a sub- 

 species. 



Glandular Persicaria. 



Frencli, Eenouee dfeiiilles de imtience. German, Ampferhldttrigcr Knuterich. 



SPECIES XII— P OLYGONUM AMPHIBIUM. Linn. 



Plates MCCXLI. MCCXLII. 

 Baiot, Fl. Gall, et Germ. Exsicc. No. 1061. 



Perennial. Rootstock rather slender, woody, branched, and exten- 

 sively creeping. Stem erect (or swimming), simple, or sparingly 

 branched. Leaves, when the plant is terrestrial, shortly stalked, 

 oblong-strapshaped or lanceolate-strapshaped, rounded or subcordate 

 at the base, attenuated towards the apex, acute : but when the plant 

 is aquatic, the leaves have conspicuous stalks, are broader, generally 

 more cordate at the base, much less attenuated towards the apex, and 

 float on the surface of the water. Ochres rather tight, not fringed, 

 or sometimes apparently so, in the terrestrial form, from the hairs which 

 clothe them projecting beyond the margins. Pacemes spikelike, cylin- 

 drical or oblong, erect, solitary or in pairs at the extremity of the stem, 

 sometimes with 1 or 2 racemosely arranged beneath the terminal one, 

 dense, continuous, not interrupted or leafy at the base. Peduncles 

 usually hairy, -vvathout glands ; pedicels shorter than the nut, articulated 

 immediately below the perianth, without glands. Perianth coloured, 

 without glands or prominent veins. Stamens 5. Styles 2, united half- 

 way up. Nut (rarely matured), much shorter than the perianth, 

 roundish-ovoid, abruptly pointed, doubly convex, finely shagreened, 

 shining. Leaves rough with very short stiff hairs in the terrestrial 



