[Herbalist] The swede-Brassica napus
Kathleen H. Keeler
kkeeler at unlserve.unl.edu
Thu Apr 22 07:33:48 PDT 2004
> are swedes period I have one source that says they
> appeared in the 17th century and one that states they
> were around in the Middle ages.
> It is believed that Brassica napus originated from a
> fortuitous hybridization between the turnip (B. rapa)
> and kale (B. oleracea acephala), probably in European
> gardens during the Middle Ages.
This quote is very like the sentences in I. H. McNaughton' s chapter in
J.Smartt & N. W. Simmonds, 1995 Evolution of crop plants, 2nd ed.
Longman Scientific & Technical, Burnt Mill, Essex...ISBN 0-582-08643-4,
an authoritative book.
"It is uncertain whether _Brassica napus_ exists in truly wild form.
Linneaus recorded it in sandy coastal areaas of Sweden but the plants he
saw may have been escapes. If wild _B. napus_ exists, it must be a
European-Mediterranean species which originated in the area of overlap
between _B. oleracea_ and the much more widely distributed _B.
" A range of morphological forms, paralleling those found in _B.
napus_ occur in _B. campestris_ the true turnip being equivalent to the
swede and there being annual and biennial oilseed forms of both species.
On this basis Olsson (1960) suggested that _B. napus_ could have arisen
several times by spontaneous hybridization of different froms of
B.campestris_ and _B. oleracea_. Thus the swede could have originated
in medieval gardens where turnips and kale grew side by side. Another
view is that the swede could have arisen by selection from an oilseed
form, but this is perhaps less likely.
"Rape has been recorded as an oilseed crop in Europe from at least the
middle ages, but which species is, unfortunately, unknown.
"Swedes were first recorded in Europe in 1620 by the Swiss botanist
Caspar Bauhin, but probably existed earlier than this (Boswell, 1949).
The introduction into Great Britain appears to have been from Sweden
around 1775-80." (all of the above, McNaughton p. 70)
The basic wild species are _Brassica oleracea_(cabbage, cauliflower,
broccoli, kale, brussel sprouts), _B. campestris_ (turnip, turnip rape,
Chinese cabbage) and _B. nigra_ (black mustard). These are diploid with
chromosome numbers of 2n = 18, 20 and 16 respectively. But they
hybridized and doubled their chromosomes to make the (also often wild)
species: _B. carinata_ (Abyssinian mustard, which is_B. oleracea x
nigra_, 2n=34), _B. napus_ (oilseed rape, rutabaga, _B. oleracea x
campestris_ 2n=38) and _B. juncea_ (leaf mustard, 2n=16, _B. campestris
x B. nigra_) [This I took from a nice summary in J F Hancock, Plant
evolution and the origin of crop species. 1992. Prentice Hall, New York
Note that the name "rape" is applied to two species there. This
continues today: the oilseed rape/canola that's the major cultivated
crop is both _B. napus_ and _B. campestris._
[They appear to have decided that _B. rapa_ was a synonym and the recent
scholarly treatments omit that name].
And there's a LOT of variation--consider that these plants are leaf,
seed, flower and root crops. You can see "kales" in Dioscorides but
can't begin to decide from a description of flowers and leaves whether
its _B. oleracea_, _B.campestris_ or _B.napa._...or...
[the references cited above by McNaughton are
G. Olsson 1960. Species crosses within the genus _Brassica_. II.
Artificial _Brassica napus_. Heriditas 46: 351-86 --Hereditas is a
well-respected British genetics journal.
V. R. Boswell. 1949. Our vegetable travelers. National Geographic
Magazine. 96: 145-217. huh, National Geographic is not usually an
authoritative source, rather a popular and readable one. But perhaps
Boswell looked at historical records no one else had.
I 'd say from all that, swedes in late period on the continent,
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