Potamogetonaceae
Potamogeton natans Linnaeus
broad-leaved pondweed
northern temperate zone
Potamogeton polygonifolius Pourret
bog pondweed
Europe, north-western Africa, eastern North America
Both common,Potamogeton natans and P.polygonifolius have been used,
doubtless interchangeably, for healing burns and scalds—either by simply
placing a relay of leaves on them or by boiling the leaves in cream and apply-
ing the product as an ointment. In two counties in south-eastern Wales
(Monmouthshire,^4 Brecknockshire^5 ) the plant in question, known as dail
llosg[y]tân,fire-burn leaves, has been botanically identified as P. natans.In the
island of Colonsay in the Inner Hebrides, where the waters by contrast are all
acid and peaty,duilleaga-bhàite,drowned-leaf, proved to be P. polygonifolius,
that member of the genus abundant there.^6
The ‘broad leaf from the pond’ formerly placed on burns in the Lleyn
Peninsula of Caernarvonshire^7 seems likely to have been Potamogeton natans,
too,while P.polygonifolius is suggested by the ‘penny leaves that are got in
the bog’ rated very highly in Limerick for the same purpose^8 —though marsh
pennywort (Hydrocotyle vulgaris) is a more dubious candidate for the latter.
Araceae
Acorus calamus Linnaeus
sweet flag
southern Asia, Africa; introduced into Europe, North America
In Britain, as elsewhere in Europe, the populations ofAcorus calamus are ster-
ile triploids and accepted as wholly introduced. The rhizome contains a gly-
coside, acorin, and has been valued medicinally since Classical times. Well
established in the wild by 1668 in Norfolk, the only part of the British Isles
where the plant has been abundant, it was long prized there by the country
folk as a remedy for ‘ague’ (credibly, in this marshy county, benign tertiary
malaria rather than other kinds of fever in this instance).^9 The rhizome was
cut into pieces, dried and then ground into a powder.
320 Potamogeton