WEDELIA. 
646 
WEDELIA. A genus of exotic, yellow-flower- 
ed plants, of the sunflower division of the com- 
posite order. Seven or eight species, varying in 
height from 6 inches to 4 or 5 feet, varying in 
adaptation from the open border to the stove, 
and variously annual and perennial, creeping 
and tuberous, herbaceous and ligneous, have been 
introduced to Britain, principally from America ; 
and all thrive in any common soil. The most 
interesting is the golden, W. awrea, a tuberous- 
rooted frame plant of about 2 feet in height, car- 
rying golden-coloured flowers in August and 
September, and introduced from Mexico in 1829. 
WEED. Any plant which grows spontaneous- 
ly on cultivated ground. It may be either use- 
less or useful, suitable for cultivation or unsuita- 
ble for it, a denizen of the poorest soils or a deni- 
zen of the richest ones, a greedy consumer of sa- 
line substances or a feeder principally upon air,an 
_indigen of the region which it infests or an intro- 
duced hardy exotic,—it may.in short, be a plant 
of any kind whatever; for it owes its proper cha- 
racter of a weed, not in the slightest to anything 
in itself, but entirely to its intrusive presence 
among plants of another kind which are growing 
or holding possession in the capacity of a crop. 
Cultivated plants themselves, therefore, are weeds 
whenever they intrude on one another, or rise 
on any spot where they are not wanted. Very 
few weeds are exotics; not many even are im- 
ported from very different soils or from consider- 
ably distant situations; and the great majority 
are simple, natural, and perhaps stubborn and 
persistent inhabitants of the ground where they 
appear, having been occupants of the very spot 
itself or of spots in its vicinity before cultivation 
began, and continuing still to maintain the oc- 
cupancy as far as cultivation will possibly admit. 
Yet very many of the most common weeds can 
be classified into groups according to the soils 
and situations which they severally love, and 
are more or less distinct indicators of the consti- 
tution or condition of the land on which they | 
grow; and some of these evanish or migrate or 
supplant one another according to the changes 
which are made on land by georgy and cultiva- 
tion. See the article Barren Sorzs, and the sec- 
tion “The Peculiar Vegetations of Soils” in the 
article Soru. 
Classification of weeds might be made on many 
principles and in many ways. But one of the 
most practically useful, having reference to the 
best systematic methods of keeping them down 
or extirpating them, is to distribute them in- 
to annuals, biennials, and perennials, accord- 
ing to the duration of their roots and to the pre- 
dominant mode of their self-propagation; an- 
other very useful classification, having reference 
to the degree in which they should be dreaded 
and the vigour with which they should be kept 
down, is to arrange them in a list of precedency 
according to the amount of injury which they 
do on a farm or of trouble which they give to a 
- WEED.. 
farmer; a third very useful classification, which 
is that adopted in “ Holdich’s Weeds of Agricul- 
ture,” and having reference to the manner in 
which they severally injure crops and trouble 
cultivators, is to distribute them into such as 
infest samples of corn, such as cannot be extir- 
pated or long kept down without the aid of fal- 
lowing, such as impoverish the soil and encumber 
crops, such as never rise in the crop or come into 
the sickle, and such as infest pasture lands; and 
a fourth very useful classification, or rather se- 
lection, having reference to the comparative bar- 
renness or unproductiveness of land, to the indi- 
cation of the character and condition of soils, and 
to the suggestion of needful processes of recla- 
mation and georgical improvement, is to distri- 
bute them into plants which are liable and ready 
to overrun so much of the surface of the ground 
as to render the produce of farm crops of little 
value, plants which spring up spontaneously 
among the herbage of sterile or exhausted pas- 
tures and meadows, and gramineous plants of 
harsh, innutritious, or noxious nature which take 
possession of pastures, downs, moors, bogs, and 
wastes to the extensive or total exclusion of good 
grasses. We shall name the principal agricul- 
tural weeds of Britain according to each of these 
four classifications; but of course, we shall do 
no more than name them, all being described in 
their respective alphabetical places throughout 
our work,—and we must neither avoid repetitions 
under the different classifications, nor attempt a 
complete list in any part of even one classifica- 
tion. 
The principal annual and biennial weeds are 
wild mustard, Sinapis arvensis,—black mustard, 
Sinapis nigra,—wild radish, Raphanus raphanis- 
trum,—corn poppy, Papaver rheas,—corn blue 
bottle, Centaurea cyanus,—corn marigold, Chry- 
santhemum segetum,—corn feverfew, Pyrethrum 
enodorum,—sow thistle, Sonchus oleraceus,—spear 
plume thistle, Cricus lanceolatus,—burdock, Arc- 
tuum lappa,—corn cockle, Agrostemma githago, 
—common chickweed, Stellaria media, — corn 
spurrey, Spergula arvensis,—goose grass, Galiwm 
aparine,—small nettle, Urtica wrens,—red dead 
nettle, Lamium purpureum,—common hemp net- 
tle, Galeopsis tetrahit,—sun spurge, Huphorbia he- 
lioscopra,—climbing buckwheat, Polygonum con- 
volvulus,—knotgrass, Polygonum aviculare,—hairy 
tare, Hrvum hirsutum,—bearded darnel, Lolium 
temulentum,—bearded wild oat, Avena fatua,— 
soft brome grass, Bromus mollis,—goose grass, 
Bromus secalinus,—cow parsnip, LHeracleum spon- 
dylium,—viper grass, Hchium vulgare,—bugloss, 
Lycopsis arvensis,—gromwell, Lithospermum offi- 
cinale—corn woundwort, Stachys arvensis,—yel- 
low rattle, Rhinanthus crista-galli,—nipplewort, 
Lapsana communis,—goosefoot, Chenopodium al- 
bum,— groundsel, Senecio vulgaris,—shepherd’s 
purse, Thlasp?i bursa-pastoris,—annual grass, Poa 
annua,—and fumitory, Pumaria officinalis.—The 
principal perennial weeds are upright meadow 
