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Shiro TSUYUZAKI
Plant community ecology / Environmental conservation

Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily

(Update on Jan. 20 2004. Last revise on Feb. 27 2010)

Weed

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Weed 雑草

An unwanted wild plant, especially one which prevents crops or garden flowers from growing property

The simplest definition I think is: "any plant that disturbs human life."

This means that the plant is weedy in some regions and is non-weedy in the other regions. For example, Pteridium aquilinum (L.) Kuhn (Bracken Fern) is a wild vegetable for Japanese and thus is not weed, but is defenitely a weed for tropical regions, in particular, in post-fire areas.

Herb

Any of several kinds of plant which appear to die at the end of the growing season but grow agian the next year, especially one which is used to make medicine or to make food taste stronger

→ herbaceous species, herbage

Weed control 雑草防除

Conparisons of weed control techniques

Control typeDirect controlHabitat manipulationOver-disturbancesBiological controlHerbicides (+Pesticides)
EffectivityLowLowLowHighHigh
CostExtremely HighLowLowCase-by-caseLow
MeritLow-costLow-costNot adequate for mass outbreakInstant remedy
DemeritHigh-cost, Waste timeLong-termLong-termPollution, Plant resistance, Herbivore may re-occur, Simple ecosystem

Over-disturbance

  • Habitat manipulation: smother crops, fertilizer, limit disturbances
  • Over-disturbances → plowing, etc. → intermediate disturbance hypothesis
  • erbicides + Pesticides: Demerit = High cost, Pollution. Plants often can get resistance to herbicides

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Weeds in Washington State

Weed species

Species Comments Species Comments
Trees/shrubs Alnus rubra (red alder) Clear cuts, roads
Cytissus scoparius (Scotch broom) Pastures, roads Hedera helix (English ivy) Urban woodlots
Hypericum perforatum (Klamath weed) Pastures, roads, clear cuts Ilex aquifolium (English holly) Urban woodlots
Lythrum salicaria (purple loosestrife) Wetlands Rubus discolor (Himalayan blackberry) Pastures, meadows, roads
Solanum dulcamara (bittersweet nightshade) Moist, shady sites Sorbus acuparia (rowan, mountain ash) Urban woodlots
Ulex europaeus (gorse) Pastures, dry hillsides Graminoids
Agropyron repens (quackgrass) Moist pastures Bromus tectorum (cheat grass) Dry pastures, steppe
Dactylis glomerata (orchard grass) Moist, rich pastures Holcus mollis (creeping velvet grass) Lawns
Juncus spp. (rushes) Wetlands, wet pastures Lolium perenne (perennial ryegrass) Pastures and meadows
Phalaris arundinacea (read canaarygrass) Wetlands Phleum pratense (timothy) Pastures, roads
Poa spp. (bluegrasses) Lawns, pastrues Herbaceous perennials
Achillea millefolium (yarrow) Lawns Arctium spp. (burdock) Roads, waste places
Bellis perennis (English daisy) Lawns and trampled areas Centaurea diffusa (diffuse knapweed) Vacant lots, roads, pastures
Chrysanthemum leucanthemum (ox-eyed daisy) Roads, clearcuts Cichorium intybus (chicory) Roads, pastures, meadows
Cirsium arvense (Canada thistle) Pastrues, roads Conium maculatum (poison hemlock) Waste places
Convolvulus spp. (bindweeds) Plantings, crops, roads Daucus carota (wild carrot) Meadows, waste places
Digitalis purpurea (foxglove) Roads Epilobium angustifolium (fireweed) Clear cuts, waste places
Equisetum arvense (horsetail) Moist waste places Glechoma hederaceae (ground ivy) Waste places
Hypochaeris glabra (false dandelion) Lawns, waste places Plantago spp. (plantains) Lawns, waste places
Polygonum cuspidatum (Japanese knotweed) Ornamentals, roads Pteridium aquilinum (bracken fern) Meadows, clear cuts
Ranunculus repens (creeping buttercup) Moist lawns, waste places Rumex acetosella (sour dock) Waste places
Rumex crispus (curly dock) Waste places Senecio jacobaea (tansy ragwort) Pastures
Sonchus arvensis (perennial sow thistle) Pastures, waste places Tanacetum vulgare (common tansey) Pastures, waste places
Taraxacum officinale (dandelion) Lawns, waste places Trifolium spp. (clover) Pastures, roads, lawns
Urtica dioica (stinging nettle) Rich farm sites, forests Verbascum thapsus (mullein) Arid roadsides
Annuals Anthemis cotula (mayweed) Trampled sites
Brassica campestris (field mustard) Mesic pastures Capsella bursa-pastoris (shepherd's purse) Waste places
Chenopodium album (lamb's quarter) Rich garden soil Erodium cicutarium (filare) Drier meadows, trampled sites
Eschscholtzia californica (California poppy) Dry, rocky urban sites Geranium molle (dove's foot geranium) Lawns, waste places
Lamium spp. (dead nettle) Meadows Matricaria matricarioides (pineapple weed) Trampled sites
Medicago lupulina (black medic) Lawns Polygonum persicaria (smartweed) Pastrues, meadows, sidewalks
Senecio vulgaris (groundsel) Gardens, roadsides Stellaria media (chickweed) Gardens

Tolerance ranges of common weeds in Washington

Moisture: X = xeric; D = dry; E = mesic; O = moist; W = wet; H=hydrid. Nutrient: P = poor fertility; L = low fertility; A = average fertility; R = rich soil; E = excessive nitrogen. Soil pH: S = strong acid; M = moderately acidic; W = weakly acidic; N = neutral.

Species name (common name) Moisture Nutrient Soil pH Comments
XDEOWH PLARE SMWN
Achillea millefolium (yarrow) xxx xxx xxx Grazed
Agropyron repens (quackgrass) xx xxx xx Disturbed, grazed
Aira carophyllea (silver hairgrass) xx xx xx Rocky, overgrazed
Alnus rubra (red alder) xxxx xx xxxx Native; floodplains & clearcuts
Amaranthus retroflexus (redroot pigweed) xxx xx xxxx
Ambrosia artemisifolia (ragweed) xxx xxx xxx
Anaphalis margaritacea (pearly everlasting) xx xx xx Native
Anthemis cotula (mayweed) xx xxx x
Arctium lappa (burdock) xxx xx
Arctium minus (common burdock) xxx xx
Artemisia vulgaris (mugwort) xx xx xxxx Greatly distributed; overgrazed
Asclepias fasicularis (narrowleaf milkweed) xx
Avena fatua (wild oats) xx xx xxx
Bellis perennis (English daisy) xx Lawns and trampled areas
Bidens frondosa (beggar ticks) xx xx
Brassica campestris (wild mustard) xxx xx Early succession in fields
Bromus tectorum (cheat grass) xx xxx Sandy, gravely soil; overgrazed
Capsella bursa-pastoris (shepherd's purse) xxx xx
Cardamine oligosperma (little bittercress) xx xxx
Centaurea cyanus (bachelor button) xx Meadows
Cerastium arvense (field chickweed) xx x xx
Cerastium viscosum (sticky mouse-ear chickweed) x xx x
Cerastium vulgatum (mouse-ear chickweed) xx xx
Chenopodium album (lambsquarter) xxx x
Chrysanthemum leucanthemum (ox-eyed daisy) xx xx xxxx
Cichorium intybus (chicory) xx x x
Cicuta douglasii (water hemlock) xx xx
Cirsium arvense (Canada thistle) xxx xx xxxx Overgrazed
Cirsium vulgare (bull thistle) xxx xx xxxx
Conium maculatum (poison hemlock) xx xxx Poisonous
Conringia orientalis (haresear mustard) x xxx Seeds poisonous
Convolvulus arvense (field bindweed) xxx xx
Convolvulus sepium (hedge bindweed) xx
Conyza canadensis (horseweed) xx xx Overgrazed
Crepis capillaris (smooth hawksbeard) xx Rocky soil
Cuscuta spp. (dodder) Parasitic
Cynoglossum officinale (hounds tongue) xxx
Cynosurus echinatus (hedgehog dogtail) xx Rocky soil
Cyperus esculentus (yellow nutgrass) xx xx Poor drainage
Cytissus scoparius (Scotch broom) xxx xx Nitrogen fixing
Dactylis glomerata (orchard grass) xx x xx Meadows
Datura stramonium (Jimsonweed) x xx Poisonous
Daucus carota (wild carrot) xx x xx
Descurania pinnata (tansey mustard) xx
Digitalis purpurea (foxglove) x xx Poisonous seeds
Digitaria sanguinalis (crabgrass) xx
Dipsaccus sylvestris (teasel) xx Ditches
Echinochola crus-galli (barnyard grass) xxx x
Elymus caput-medsae (Medusa head) xxx
Epilobium angustifolium (fireweed) xxx xx After fires; native
Epilobium minutum (willowweed) xx xxx
Equisetum arvense (field horsetail) xxx xxx xx
Erodium cicutarium (filare) xx xx xx Rocky, open fields
Eschscholtzia californica (California poppy) xx Rocky sites
Euphorbia peplus (petty spurge) xx xx Shaded
Galium aparine (bedstraw) xx xx Shaded
Geranium carolinianum (Carolina geranium) x
Geranium molle (dove's foot geranium) xx xxx Open
Geranium robertianum (Robert's geranium) xx xxx
Geranium pusillum (small geranium) x xx
Glechoma hederaceae (ground ivy) xx x Woods, moist lawns
Helianthus annus (sunflower) xx xxx
Hedera helix (English ivy) xx xxx
Holcus lanatus (velvet grass) xxx xx
Holcus mollis (creeping velvet grass) xx xx
Hordeum jubatum (foxtail barley) xx xxx Tolerates saline soil
Hyoscyamus niger (black henbane) xx xx
Hypericum perforatum (Klamath weed) xx xx Poisonous
Hypochaeris glabra (false dandelion) xx x
Hypochaeris radicata (false dandelion) xx x x Lawns
Ilex aquifolium (English holly) xx xx
Iva axillaris (poverty weed) x
Juncus effusus (soft rush) xx x x
Juncus tennuis (slender rush) xx
Lactuca serriola (prickly lettuce) xx xx
Lamium amplexicaule (henbit) xx xx
Lamium purpurea (dead nettle) xxx xx xx
Lapsana communis (nipplewort) xx
Lepidium virginicum (Virginia pepperweed) xx
Linaria vulgaris (yellow toadflax) xx xx
Lolium perenne (perennial ryegrass) xx xx Pastures
Lotus corniculatus (bird's foot tre-foil) xx xx Lawns
Lychnis alba (white cockle) xx
Lysimachia nummularia (moneywort) xx xxx xxx
Lythrum salicaria (purple loosestrife) xx xx Marshes, lakes
Malva neglecta (cheeseplant) xx
Matricaria matricarioides (pineapple weed) xx x Trampling
Melilotus alba (white sweet colver) xx xx Pastures
Medicago lupulina (black medic) xx xx Lawns
Mentha arvensis (field mint) xx
Mollugo verticillata (carpetweed) xx xx
Oxalis stricta (yellow wood sorrel) xx
Paspalum distichum (knotgrass)
Phalaris arundinacea (reedgrass) xx xx xx Ditches
Phleum pratense (timothy) xx x Pastures
Phragmites communis (reedgrass) x xxx x Ditches, lakes
Plantago lanceolara (English plantain) xxxx xxxx xxx
Plantago major (broad leaf plantain) xx xxxx xxxx Trampling
Poa annua (annual bluegrass) xx xx xxxx Lawns
Poa compressa (Canada bluegrass) xx xx xx
Poa pratense (Kentucky bluegrass) xxxx xxx xxxx Lawns, meadows
Poa trivialis (roughstalk bluegrass) xx xx
Polygonum aviculare (knotweed) x xx Trampling
Polygonum convolvulus (black bindweed) xxxx xx xx
Polygonum cuspidatum (Japanese knotweed) xx xxx
Polygonum persicaria (smartweed) xx xx
Polypogon monspeliensis (rabbit foot grass) xxxxx xx Tolerates brackish water
Portulaca oleracea (purslane) xxx xx
Prunella vulgaris (heal-all) xxxx xxx xxxx
Pteridium aquilinum (bracken fern) xxx xx xx Native; carcinogenic
Ranunculus acris (tall field buttercup) xx xxx xxxx Heavy soils
Ranunculus repens (creeping buttercup) xx xxxx xxxx Wet lawns
Rhus diversiloba (poison oak) xx Native; causes skin irritation
Rosa canina (dog rose) xx Hegergrows
Rubus discolor (Himalayan blackberry) xxx xx
Rubus laciniatus (evergreen blackberry) xxx xxx
Rumex acetocella (sour dock) xx xx x
Rumex crispus (curly dock) xx xx xxxx
Saponaria officinalis (saopwrot; bouncing bet) xxx
Senecio jacobaea (tansy ragwort) xxx xx x Poisonous
Senecio sylvestris (woodland groundsel) xx
Senecio vulgaris (groundsel) xx
Setaria viridis (green foxtail) xxx x
Silene cucubalis (bladder campion) xx xx
Sisymbrium officinale (hege mustard) xx xx
Solanum dulcamara (bittersweet nightshade) xx Poisonous
Solanum nigrum (black nightshade) xx xx Poisonous
Solidago canadnesis (goldenrod) xx xx
Sonchus arvensis (perennial sow thistle) xxx xxx
Sonchus asper (prickley thistle) xxx xxx
Sonchus oleraceus (annual sowthistle) xx xxx
Sorbus acuparia (mountain ash) xx xx
Spergula arvensis (corn spurry) xxx xx
Stellaria media (chickweed) xx xx
Tanacetum vulgare (tansey) xx
Taraxacum officinale (dandelion) xxxx xx xxxx Lawns
Thlaspi arvense (pennycress) xxx x
Tragopogon dubius (goatsbeard) xx xxx
Trifolium dubium (small hop clover) x x x Nitrogen fixer
Trifolium pratense (red clover) xxxx xx xxxx Nitrogen fixer
Trifolium procumbens (low hop clover) xxx xxx xxx Nitrogen fixer
Trifolium repens (white clover) xxxx xxx xxxx Nitrogen fixer
Triglochin maritimum (seaside arrowgrass) xx xxx Salt tolerant
Typha latifolia (cattail) x xx Wetlands
Urtica dioica (stinging nettle) xxx xx xxxx
Ulex europaeus (gorse) xx Overgrazed; nitrogen fixer
Verbascum blattaria (moth mullein) xx xx
Verbascum thapsus (mullein) xxx xx xx
Veronica peregrina (purslane speedwell) xx
Veronica seryphylla (winter speedwell) xx xx
Vicia sativa (vetch) xx xx Nitrogen fixer
Vinca major (periwinkle) xx xx Moist, shaded slopes

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References

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