Plants grow preferably where they find the food they need in an environment at which they are adapted. By examining which plants occur on the soils, you can also think reverse. In a non- disturbed environments (by soil cultivation, herbicide,..) the naturally-occurring plants, may give an indication of the soil.
Do not take conclusions on one example, but several healthy plants of the same species.
They can give an indication regarding nitrogen and fertility, water management (or drought), soil structure and acidity of the soil.

This form of biomonitoring is also used to keep an eye on health. (?) of shoulders alongside highways.

Fertility, nitrogen level

Poor soil
stork's bill (Erodium cicutarium),
(corn) poppy (Papaver)
(common or sheep) sorrel (Rumex acetosa),
(early) whitlow (grass)(Erophila verna)

Soil nitrogen
chamomile (Matricaria chamomilla),
long headed poppy (Papaver dubium)
marsh cud weed (Gnaphalium uliginosum),
prickly poppy (Papaver argemone)

Nitrogen poor soil
sweet vernal grass (Anthoxanthum odoratum),
broad leaved thyme (Thymus pulegioides)
clovers,
hawkweed (Hieracium arvensis)
sheep fescue (Festuco ovina)
vetches,

Nitrogen- rich (much fertilized)

Canada thistle (Cirsium arvense),
field speedwell (Veronica agrestis),
(stinging) nettle (Urtica),
black grass, slender meadow foxtail (Alopecurus myosuroides),
fumitory (Fumaria)
hedge mustard (Sisymbrium officinale),
field speedwell (Veronica persica),
hairy (shaggy) soldier (Galinsoga quadriradiata),
shepherd's purse (Capsella bursa-pastoris),
henbit (Lamium amplexicaule),
goose grass, sticky weed (Galium aparine)
groundsel (Senecio vulgaris),
speedwell ivy (Veronica hederifolia),
sun spurge (Euphorbia helioscopia),
Lamb's Quarters (Chenopodium album),
chickenwort (Stellaria (media)),
dandelion (Taraxacum officinale)
(spotted) ladiesthumb (Persicaria maculosa),
broad-leaved dock (Rumex obtusifolius),
comfrey (Symphytum officinale),
wall flower (Erysimum),
spear orach (Atriplex patula),
bishop’s weed (Aegopodium podagraria),
black bindweed (Fallopia convolvulus),
black nightshade, petty morel (Solanum nigrum),

Nitrogen-rich fertile soil
Canada thistle (Cirsium arvense),
borage (Borago officinalis),
mugwort, mugwood (Artemisia vulgaris)
deadnettle (Lamium),
speedwell, gipsyweed (Veronica),
cow parsley (Anthriscus sylvestris),
cow parsnip, hogweed (Heracleum sphondylium)
elder (Sambucus nigra) (thrives even on a dunghill)
stinging nettle (Urtica dioica)
shepherd's purse (Capsella bursa- pstoris)
cleavers, goose grass (Galium aparine)
small nettle (Urtica urens)
lamb’s quarters - (Chenopodium album)
dandelion (Taraxacum officinale),
spear orach (Artiplex patula)
chickweed (Stellaria media),

Highly nitrogenous
cleavers, goose grass (Galium aparine)
dwarf mallow (Malva neglecta),
common groundsel (Senecio vulgaris),
red goosefoot (Chenopodium rubrum),
black nightshade (Solanum nigrum),


Acidity

Highly acidic soils (pH (H2O) <5)
annual knawel (Scleranthus annuus),
corn spurrey (Spergula arvensis),
(common) knotgrass (Polygonum aviculare),
plantain (Plantago),
sorrel (Rumex)

Acidic soils (5 < pH (H2O) < 6.5)
bracken (Pteridium aquillinum)
field pansy (Viola arvensis),
Bilberry, blueberry (Vaccinium myrtillus)
wavy hairgrass (Avenelle flexuosa)
nard grass (Nardus stricta)
hearts’ ease (Viola tricolor),
chamomile (Matricaria chamomilla),

corn chamomile (Anthemis arvensis),
creeping soft grass (Holcus millois)
long headed poppy (Papaver dubium)

prickly poppy (Papaver argemone)
marsh cud weed (Gnaphalium uliginosum),
wild radish (Raphanus raphanistrum),,
stork's bill, redstem filaree (Erodium cicutarium),
red sandspurry (Spergularia rubra),
sheep sorrel (Rumex acetosella)
corn spurrey (Spergula arvensis),
common yellow woodsorrel (Oxalis stricta),
heather (Caluna vulgaris)
corn chamomile (Anthemis arvensis),

Neutral soils (6.5 < pH (H2O) < 7.5)
field speedwell (Veronica agrestis),
sow thistle (Sonchus arvensis),
black grass, slender meadow foxtail (Alopecurus myosuroides),
wormseed mustard (Erysimum cheiranthoides),
field speedwell (Veronica persica),
field horsetail (Equisetum arvense),
shepherd's purse (Capsella bursa-pstoris),
yellow sweet clover (Melilotus officinalis),
poppy (Papaver),
cleavers, goose grass (Galium aparine)
speedwell ivy (Veronica hederifolia),
sun spurge (Euphorbia helioscopia),
purple dead nettle (Lamium purpureum),
scentless mayweed (Tripleurospermum maritimum),
chickweed (Stellaria media),
black nightshade (Solanum nigrum),

Alkaline soils (7.5 < pH (H2O)) = Alkaline alkaline soil
field pansy (Viola arvensis),
maple-leaved goosefoot (Chenopodium hybridum),
wood betony or heal all, fever herb (Stachys officinalis)
blue grass (Sesleria varia)
self heal (Sanicula europaea)
wild musterd (-turnip) (Sinapis arvensis),
black medik (Medicago lupulina)
poppy (Papaver)
salad burnet (Sanguisorba minor)
sage meadow (-clary) (Salvia pratensis),
forking larkspur (Consolida regalis)
pheasant’s eye (Adonis aestivalis)


Water resources

Very dry
stonecrop (Sedum acre),
Bird's-foot (Ornithopus perpusillus)

Dry soil
lamb’s quarter (Chenopodium)
corn buttercup (Ranunculus arvensis)
Canadian fleabane (Conyza canadensis)
yarrow (Achillea millefolium)
annual mercury (Mercurialis annua)
dyer’s chamomile (Anthemis tinctuoria)
stork's bill (Erodium cicutarium),
broad leaved thyme (Thymus pulegioides)
shaggy soldier (Galinsoga quadriradiata)
shepherd's purse (Capsella bursa-pstoris),

yellow sweet clover (Melilotus officinalis)
annual bugloss (Lycopsis arvensis)
lady’s thumb (Persicaria maculosa)
evening primrose (Oenothera)
early whitlow grass (Erophila verna)
cranes bill, dovefoot (Geranium molle)

Moist soil
sow thistle (Sonchus arvensis),
fumitory, earth smoke (Fumaria officinalis)
field horsetail (Equisetum arvense)
poppy (Papaver),
dwarf mallow (Malva neglecta),
hairy bitter cress (Cardamine hirsuta),
lesser swine cress (Coronopus didymus),
speedwell ivy (Veronica hederifolia),
sun spurge (Euphorbia helioscopia)
purple dead nettle (Lamium purpureum),
(spotted) ladiesthumb (Persicaria maculosa),
scarlet pimpernel (Anagallis arvensis)
lesser celandine (Ranunculus ficaria)
corn spurrey (Spergula arvensis),
common yellow woodsorrel (Oxalis stricta),
corn speedwell (Veronica arvensis)
black nightshade (Solanum nigrum),

Wet soil
corn mint (Mentha arvensis),
field horsetail (Equisetum arvense),
heal-all (Stachys)
wood club rush (Scripus sylvaticus),
(common) knotgrass (Polygonum aviculare),
raged robin (Lychnis flos - cuculi)
wood sorrel (Oxalis spp.)
coltsfoot (Tussilago farfara)
creeping buttercup (Alopecurus geniculatus)
snakeroots, boneset (Eupatorium spp.)
cattail (Typha spp.)
marsh cud weed (Gnaphalium uliginosum),
cabbage thistle (Cirsium oleraceum),
mosses (Bryophyta),,
compact rush (Juncus conglomeratus)
horsetails (Equiestum spp.)
purple moor grass (Molinia caerilea),
cuckoo-flower, lady’s smock (Cardamine pratensis)
soft rush (Juncus effusus)
rushes (juncus spp)
greater swine-cress (Coronopus sqamatus)
water rushes (Scripus spp.)
sedge (Carex spp.)
sorrel (Rumex spp.)


Compacted soil These herbs indicate that the soil is compacted by trampling or after working with heavy machinery.
Canada thistle (Cirsium arvense),
chamomile (Matricaria chamomilla),
(water- or) marsh foxtail (Alopecurus geniculatus)
grasses,
large plantain (Plantago major),
horsetail (Equisetum arvense)
creeping buttercup (Alopecurus geniculatus),
reed sweet-grass (Glyceria maxima)
floating manna grass Glyceria fluitans)
dandelion (Taraxacum ifficinale)
broad-leaved dock (Rumex obtusifolius),
reed canary grass (Phalaris arundinacea)
annual blue grass(Poa annua)
hogweed (Polyfonum aviculare)
water pepper, smart weed (Persicaria hydropiper)
silverweed (Ptentilla anserina)


Soil structure

Poor structure
field bindweed (Convolvulus arvensis),
lesser swine cress (Coronopus didymus),
creeping buttercup (Alopecurus geniculatus),
couch grass(Elytrigia repens)

annual blue grass(Poa annua)
hogweed (Polyfonum aviculare)

Good structure
fumitory, earth smoke (Fumaria officinalis)
speedwell species,
small nettle (Urtica urens)
purple dead nettle (Lamium purpureum),


Trees as indicator

Sandy loam and loam soils:
common ash (Fraxius excelsior)
sycamore maple (Acer pseudoplatanus)
hornbeam (Carpinus betulus)
small-leaved lime (Tilia coedata)
poplar (Populus spp)
sessile oak (Quercus petraea)
oak (Quercus robur)

Sandy soils:
sessile oak (Quercus petraea)
oak (Quercus robur)

Dry soils:
goat willow (Salix caprea)
field maple (Acer campestre)
sessile oak (Quercus petraea)


See also <Gras chooses soil> and <Geobotany>