Page:Journal of botany, British and foreign, Volume 9 (1871).djvu/216

 194 ON BRASSrCA rOLYMOUPIIA.

describes two forms; one, aimuol, with a sleutler root and rapid produo- tiou of seeds, lending itself to the purposes of the oil-expresser ; the other, biennial, with a root which is enlarged and escident. Probably, a succulent-rooted variety of almost any plant with anything- like a biennial habit, might be obtained by patient cidtivation and selection. Turnip- rooted forms of Chervil {Authriscus CerefoUum, Hotfm.) and Parsley (Pefroseliiiitm sativum, Hofim.) may be bought in the shops ; even the wild Radish {RaplumusRaplianldrum, L.) has been made in France, as a matter of experiment, to yield an esculent root. Generally speaking, a generous supply of food tends to develope the leafy or nutritive organs of such plants, and checks the evolution of the reproductive organs — or, what is in biennials practically the same thing, the growth of the ascending- axis. Hence these plants when stinted in their food, as when growing amongst standing crops, rapidly run up and attain maturity ; or, in other words, are apt to become annuals.

B. campc'stris, De Cand. (I.e. 588J, includes two very important agri- cultural plants — the Swedish Turnip and the Rape or Colza. As far as my experience of these plants goes, they certainly are forms of the same species, only differing in the presence or absence of an enlarged root. If the mature radical leaves of either form of this plant be examined both will seem almost glabrous, and it is only by a careful scrutiny of the ribs on the uuder surface that a few scattered cartilaginous hairs can be detected ; the young leaves are, however, quite obviously hispid. It is worth while remarking that externally there is a wade difference between the root of the Swede and the ordinary Turnip, which is well known to agriculturists. The Turnip, whether globe or tankard {depres&d or obJoucja) has the crown of leaves sessile without any elongation of the iuternodes. The Swede, which, without being oblong is straight-sided in its middle, has its upper portion prolonged into a "neck" marked by the scars, separated by partially developed iuternodes of the decayed lower leaves of the crown. Of the history of the Swedish Turnip (var. Napo-Brasslca, De Cand.) almost nothing seems to be known. De Candolle remarks, that possibly it may be a hybrid between B. campedrh (Rape) and B. Rapa ; and Mr. Buckman states " that the seeding of Rape and common Turnips in mixed rows has resulted in the production of malformed Swedes ; which, however, improved very much by careful cultivation " ('Treasury of Botany,' p. 165). Lamarck, struck probably with the character of the iieek, observes that the Swede is a variety in the same race as the Chou-rave {B. oleracea, var. cnnlo-rapa, De Cand.), the Kohl- rabi of English seedsmen ; and this would be pretty nearly the opinion of LinuEeus, if, as it seems probable, De Candolle is right in quoting, as a synonym of the Swede, B. oleracea, var. Napo-Brassica, L. (Sp. 932), identified with J3. Napus, var. y. escidenla by Kocli, who seems to include the hispid Rape as well as the Swede under Napus. One variety of the Swede has large entire cabbage-like leaves (Wilson, ' Farm Crops,' i. 275). Mr. Watson, in his second paper, remarks that " Turnip and Swede are species about as distinct from each other as Swede and Cabbage " (viii. 370). He is certainly correct in contrasting the larger and pale orange-coloured flowers of the Swede with the bright buttercup yellow of the Turnip. Hybrids permanent in their characters have been obtained between the Swede and the White Turnip, and are quoted in seedsmen's lists. It cannot be doubted that both Swede and Rape must often occur

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