ON POLYGONUM NODOSUM. 35
well be the case if the fig, 868, in the illustrated edition of the 'Hand- book of the British Flora' be accepted as characteristic of P. Persicaria. It has, however, all the habit of P. maculatum, and the stifles are repre- sented unconnected and deflexed as in P. lapathi folium.
About London P. Persicaria, L., presents itself in the typical form, well figured in a new plate by Syme in E. B. MCCXXXVIL, and by Reichen- bach (Iconog. Bot. ic. 684). This lias a stem rarely spotted, with rather loosely arranged divaricating branches and stout, rather short (com- pared with P. maculatum), blunt, oblong or cyliiulrical, remote racemes. The plant figured by Curtis (Flor. Lond. f. 1) is prol)ably a luxuriant state of the type. The old figure of P. Persicaria, E. B. 756, now used by Syme to illustrate the variety tlatnm, is one from which all definite characters seem to have evaporated, and is almost valueless. The authentic speci- mens of P. Persicaria in Sowerby's herbarium are really P. maculatum , and it is by no means impossible that this plant was in part copied by the artist, though the details are from P. Persicaria.
A much rarer form of this species occurs occasionally in moist culti- vated ground. It may be distinguished from the type by its more succu- lent and swollen stem, ascending and not divaricate branches, and racemes not cylindrical, but longer and attenuated upwards, contracted when young into a panicle. The foliage also is somewhat weaker in texture, and of a livelier green. This is the P. biforme of Wahlenberg (Suec. n. 437) and of Fries (Mant. ii. p. 28), who quotes Curtis's figure, in which he is per- haps right,* and also Reichenbach's, which belongs to the more typical form. Authentic specimens of P. biforme, from Fries, in the Kew Her- barium, it is noticeable have ochrese without cilia, though this does not ac- cord with the description. P. Persicaria, (3. elatum (Gren. et Godr. Fl. de Fr. vol. iii. p. 48), is another synonym, and it has already been shown to be probably the true P. nodosum, of Persoon. P. laxum, Reich., which seems to have nothing really to do with P. maculatum., may be also cap- able of inclusion here. Some writers (Boreau, Fl. du Cent, de la Fr. ed. 3, t. ii. p. 557, Gren. et Godr. 1. c. p. 49) regard P. laxum, Reich., as a hybrid between P. Hydropiper and P. maculatum. If so, it is remarkable that a glandless plant should be the offspring of two glandular parents. Fries says of this plant " transitus ad Mite,'^ (Mant. vol. ii. p. 26). f A curious variety referable to the typical form of P. Persicaria, but which may be really a hybrid, has the peduncles slightly glandular hispid. It has been distributed by Mr. Watson from Esher, and has been noticed at Kilburn and Haverstock Hill. There are also specimens from Essex in E. Forster's herbarium.
It will be convenient to give the characters and synonymy in a col- lected form. J
- In Fl. Midd. p. 244, we have also quoted it, but our notion of this form was
at that time more compreliensive tlian now.
t Reichenbach, in his description in tlie ' Iconographia Botanica,' was not disposed to accept the suggestion of hybridity, remarking " nimis enim prodigiosa mihi videtur hybi'iditas hodierna. However, in the ' Flora Excursoria,' 3696, he gives Hi/dropiperl-nodosum as a synonym, with the explanation " Inflorosccntia densa gracilis floresqne parvi rosei P. nodosi, folia contra et ochreoe P. Hi/dropiperis.'^
J Linnceus seems to have founded his P. lapathifolium on a species of Tournefort's, and the only locality he gives is " Gallia" ; as he describes the plant as " lloribus . . . semidigyuis," it is somewhat doubtful what he really meant. The Liunean Herba- rium only confuses matters, the specimen named " lapathifoUunC^ being a widely
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