Classif.Nat. Order of Cruciferous. Tetradynamia siliquosa L.
Genus NASTURTIUM. Calix with four equal spreading folioles, corolla with four equal petals, stamina six tetradidynamous, silique subterete and short, with convex valves, not carinate nor nervose.
Sp. Nasturtium palustre. Root fusiform, stem branched, leaves lyrate pinnatifid, smooth, with unequal teeth, petals as long as the calyx and yellow, siliques short and turgid.
Description. Root perennial, fusiform. Stem one or two feet high, branched, nearly dichotome, leaves alternate, nearly sessile, smooth, spreading, lyrate or pinnatifid at the base, with confluent oval lobes, last segment large, oval, oblong, sinuate, subacute, with many unequal teeth and gashes, racemes of terminal flowers, pedicels short, calyx and corolla obtuse and equal, siliques divaricate, oblong, acuminate, turgid, or swelled.
History. The genus Nasturtium or Water cress, is one of those established by Tournefort, &c. which Linnaeus thought proper to reject; this was united to Sisymbrium, and thus this plant is the Sisymbrium palustre of the Linnaean botanists; but Jussieu, Decandolle, &c. have found needful to restore the G. nasturtium. The common Water cress is the N. officinale or Sisymbrium nasturtium of L.; it differs from this by white flowers and pinnate cordate leaves. They both, grow near, or in water brooks, swamps, ponds, in North America and Europe. The N. amphibium is also common to both continents, and a few peculiar species or varieties are spread through the United States, not yet well distinguished. My N. diffusum and N. arcuatum grow in the Western States. The N. tuberosum of my Flora Ludov. belongs to a peculiar subgenus, with a rounded notched silique; I call it Brachobium. All these plants blossom generally in June and July, but the N. tuberosum in February. They are alike in taste and properties. They can all be eaten in sallad, and form a good spring diet. Their taste is warm, pungent, and somewhat acrid, like that of Lepidium and Radishes, but by no means unpalatable, and mixed with a sweet juicy flavour.
Properties. A mild stimulant, diuretic, antiscorbutic, deobstruent, abstergent, hepatic, and stomachic. The whole plants must be used fresh, in sallad or their fresh juice, since these properties are lost by drying and boiling. The leaves may be found all the year round, but are best in the spring; they are then a very useful diet for those who have scorbutic affections and spots, spungy gums, liver complaints, scorbutic rheumatism, pituitous asthma, &c. Water cresses are excellent and milder substitutes to horse radish or cochlearia, mustard, and scurvy grass, in almost all cases, except in palsy. Their active properties reside, as in all the Cruciferous, in an acrid volatile oil, containing sulphur and an ammoniacal salt.
Water cresses were formerly used for many other diseases, in gravel, histerical affections, diarrhoea, and obstipation, polypus, and even worms; but these are not sufficient proofs of their service in these complaints. They are better in cold and sour stomachs, which they warm and revive. All the cruciferous plants which have the same taste, are good equivalents; such are many species of Lepidium, Cardamine, Arabiz, Sisymbrium, Cochlearia, &c. Those which have edible tuberous roots, like N. palustre, N. tuberosum, Arabis tuberosa, &c. ought to be cultivated, these roots being a good condiment, somewhat like radishes, but milder; the root of N. palustre has a stronger taste, and has been wrongly deemed injurious by some.
Medical Flora, or Manual of the Medical Botany of the United States of North America, Vol. 2, 1830, was written by C. S. Rafinesque.