Woods, Hedges and Fields - Gower - page 269

In the older literature many of these species are referred to as 'arable weeds', being definitely, as the
dictionarydefinesit,'aplantgrowingwhereitisnotwanted'asfarasthefarmerwasconcerned.Newde-
scriptions use the term 'arable plants' in recognition of their conservation importance. Probably the most
well-known arable plant is the poppy Papaver rhoeas , but it is interesting that, compared to England,
poppies are relatively uncommon in Wales and fumitories, a close relative, occur in abundance instead.
Nationally scarce species found include tall ramping-fumitory Fumaria bastardii and common ramping-
fumitory F. muralis.
In contrast to many other parts of Britain, the continuous history of mixed farming in Gower has pre-
served the habitat of what was once a plentiful and diverse arable flora. A study by Quentin Kay (1997a)
showed that the arable plant communities in Gower are still very much richer in species than the increas-
ingly impoverished arable floras that are now the normal situation for lowland Britain. The arable plants
alsooftenextendrightacrossthefield,ratherthanbeingmainlyconfinedtothemargins,assooftenisthe
case in England. This has an additional advantage in that wintering flocks of birds prefer to forage in the
centre of the fields away from the hedges where there may be predators.
Although many of the plants are still present, they are considerably reduced in abundance. While
it is still not too difficult to find Gower fields with scattered specimens of increasingly rare plants like
corn marigold Chrysanthemum segetum (Fig. 153), sharp-leaved fluellen Kickxia elatine or wild radish
Raphanus raphanistrum these species are no longer as common as they were twenty years ago. Unfortu-
natelytherearenorecentrecordsforsomearableplantsthatusedtooccurextremelylocallyorasrarities,
suchascornchamomile Anthemisarvensis andlessersnapdragon Misopatesorontium ,butitseemshighly
likely that they will be found again, along with other species not previously recorded from the area. Until
2002 broad-fruited cornsalad Valerianella rimosa was thought to have been extinct in Wales until it was
found in a Gower field, the first record for fifty years. Similarly, small-flowered catchfly Silene gallica ,
once thought to be lost from Gower, was recorded again in 2003.
Arable plants vary in their adaptation to the specialised habitat of cultivated land, and three broad
classes are recognised. First are obligate plants, which onlygrowincultivated land. Wild radish isagood
example since it appears to grow only in cultivated land throughout its world range. Some semi-obligate
plants grow mainly in arable land in Britain, but also occur in some isolated natural habitats where they
seem to be native. It seems likely, therefore, that they have originated from weed populations in the past.
The nit-grass found on the Gower cliffs probably originated in this way, first arriving in the peninsula as
an annual weed of cultivated land. Like the nit-grass, arable plants of this class are often ecologically re-
stricted,decliningonarablelandandrareorscarceintheirnaturalhabitats.Thesecondclassis facultative
plants. These grow both as plants in arable crops and also in other habitats in the same geographic area.
A familiar example is annual meadow-grass Poa annua , which is now the most widespread and abundant
non-crop plant in the arable fields. Annual meadow-grass is, as its name suggests, an annual, but facultat-
ive plants are often perennials, such as creeping buttercup Ranunculus repens . Many facultative plants
show considerable variation within the species, with clear genetic differences between arable and non-ar-
able populations. The third class is casual plants. These are species which occasionally appear as arable
plants,originatingeitherasaresultofnaturaldispersalfromotherhabitatsinthesameareaorasintroduc-
tions with seeds or fertilising material such as slurry. They are normally non-persistent and usually grow
asisolatedindividuals.ExamplesfromGowerincluderosebaywillow-herb Chamerion angustifolium and
common gorse.