This section is from the book "An Experimental History Of The Materia Medica", by William Lewis.
Navew: a plant of the turnep kind, with oblong roots growing slenderer from the top to the extremity. Two sorts of it, ranked among the articles of the materia medica, are supposed by Linnaeus to be only varieties, and are therefore joined into one species, under the name of brqffica (napus) radice caulefcente fusiformi. They are both biennial.
(a) Ray, Historia plant arum, tom. ii. p. 1707.
(b) Linnaei, Amaen. Academic, iii. 96.
1. Napus, dulcis officinarum. Napus fativa C. B. Garden or sweet navew, or French turnep: cultivated for the culinary use of its roots, which are warmer and more grateful than those of the common turnep, and are said to afford likewise, in their decoctions, a liquor beneficial in disorders of the breast. The seeds, in figure roundish and in colour reddish, are the part principally directed for medicinal purposes: they have a moderately pungent taste, somewhat approaching to that of mustard seed, of the virtues of which they appear to partake: with mustard seed they agree also in their pharmaceutic properties, their pungent matter being taken up completely by water, and only partially by rectified spirit, and being dissipated in the infpiffation of the watery infusion, only an unpleasant bitterishness remaining in the extract. As the navew seeds, nearly similar in kind to those of mustard, are apparently much inferiour in degree, the college of Edinburgh has discarded them, and that of London retains them only as an ingredient in theriaca.
2. Bunias Pharm. Paris. Napus silvestris C. B. Wild navew, or rape: growing on dry banks and among corn: with leaves somewhat different from those of the preceding, being more like those of cabbages than of turneps; the root smaller, and of a stronger unpleasant taste; and the seeds also rather more pungent, on which account they are preferred by the faculty of Paris. The seeds of both kinds yield upon expression a large quantity of oil: the oil called rape-oil is extracted from the seeds of the wild sort, which is cultivated in abundance, for that use, in some parts of England; the cake, remaining after the expression of the oil, retains, like that of mustard, the acrimony of the seeds.