Brassica rapa L., Turnip
Account Summary
Introduction, archaeophyte, occasional. Native range obscured by long cultivation, but probably it is Eurasian southern-temperate.
1900; Praeger, R.Ll.; Florencecourt.
April to December.
Fermanagh occurrence

Turnip has been recorded in a total of 78 tetrads, 14.8% of the total in Fermanagh. It is an occasional species on riverbanks, waste ground, roadsides, quarries and sand pits. The records are rather widely scattered across the VC but, as would be expected, this tall annual or biennial is most frequently found in the more fertile, lowland, farming area lying to the east of Lough Erne.
RHN and the current author (R.S. Forbes) feel that B. rapa is probably under-recorded and the species more common than the tetrad map indicates. We make this suggestion knowing that this taxonomically complicated group of plants naturally leads to identification confusion for all concerned. We also believe that, perhaps more so in the past than now, some field workers in Fermanagh choose to ignore obvious escapes from cultivation.
At the same time, due to an easily understood confusion between several very similar yellow-flowered taxa of the genus Brassica (plus a plethora of names and complicated synonymy), it is quite conceivable that some of the B. rapa records in the Fermanagh Flora Database might really refer to one or other of two forms of B. napus L., ie subsp. oleifera (DC) Metzg. (Oil-seed Rape) or subsp. rapifera Metzg (Swede) (Rich 1987c, 1991). The situation regarding names is not helped by there also existing a variety of B. rapa subsp. oleifera called 'Turnip-rape'. This is another oil-seed and fodder crop plant, which occurs in Britain as a casual alien (Clement & Foster 1994; Stace 1997). B. napus subsp. oleifera has been more widely grown in Ireland in recent years, although not to any great extent in Fermanagh in comparison, for instance, to the more arable areas of south-eastern NI and especially in Co Down (H38).
The Swedish turnip is an orange-yellow fleshed swollen Rape root, usually referred to simply as 'Swede', and botanically named B. napus subsp. rapifera. It is cultivated for animal and human consumption and is usually eaten in the wintertime. It may also occasionally escape into disturbed sites, especially where farm, garden or kitchen material is used or dumped. Swede is often sold under the incorrect name of turnip in NI, adding to any existing confusion the reader may already be experiencing!
In Fermanagh, we consider both Irish forms of B. rapa to be present (ie Wild Turnip and the cultivated Turnip), either as occasional recent escapes from cultivation, or older, feral derivatives or reversions from such escapes. B. rapa subsp. campestris (L.) A.R. Clapham (Wild Turnip) is sometimes locally abundant as a casual ruderal weed on disturbed ground, roadsides and waste ground, but it also occurs as a larger, biennial, semi-persistent and apparently naturalised form on unstable river banks, winter-flooded lakeshores, quarry ponds, sand-pits stream-sides and ditches. Clapham et al. (1962, 1987) considered it doubtful whether these two forms of subsp. campestris are genetically distinct.
Wild Turnip appears in urban situations too, especially in neglected ground in and around country villages and also in church grounds in a few instances. Quite where the latter form of the plant springs from remains something of a mystery, but perhaps soil disturbance in the form of grave digging and church yard tending may be all that is required!
Irish occurrence
The New Atlas map shows that B. rapa s.l. is a very frequent and widespread archaeophyte throughout most of lowland Ireland, with the exception of the most acidic peaty and mountainous areas, eg in Co Donegal, the Mourne mountains in Co Down, and in Connemara. Reynolds (2002) also reckons that R. rapa is common and locally abundant in Ireland both as a ruderal and in more natural habitats. She also considers B. rapa subsp. rapa with its swollen 'root' to be less common than subsp. campestris with normal tap roots.
British occurrence
In Britain, likewise, B. rapa is widespread in most of England and Wales, but its distribution becomes increasingly fragmented and more coastal northwards into Scotland (Preston et al. 2002).
Plant and seed ecology
The seed of B. rapa s.l. is long-persistent in the soil seed bank, surviving at least five years and possibly very much longer (Thompson et al. 1997). Some form of regular disturbance of the upper soil horizons is necessary to enable germination and the maintenance of a recurring population in a particular site or area and subsp. campestris, in particular, requires and must have sufficient competitive ability in order to maintain its local presence. Information on the ecological requirements and tolerances of the subspecies does not appear to exist and further study is clearly required.
An excellent summary of the history of B. rapa cultivars can be found in Simmonds (1976) and in Zohary & Hopf (2000).
Threats
None.