Common Name
Scientific Name

Blooming Period Locations Dispersal Agents Photo
Control Method Habitats / Comments
  Plants ranked #1 on park priority list: Highly invasive. Should have immediate management
  Algerian ivy
Hedera canariensis

Mid-Sept Lower and Middle Park Vegetative, birds Photo of Hedera canariensis Riparian, woodland, encroaching from neighboring residential properties
  American pokeweed
Phytolacca americana

Early Jul-Oct. Lower and Middle Park Birds Photo of Phytolacca americana Riparian; spreading rapidly in Bidwell Park, becoming a fairly common weed in the Chico Urban Area.
  Barbed goatgrass
Aegilops triuncialis

Early May Upper Park 100′ east of start of Middle Trail by Lot A, Pine Trailhead, Guardian Trail by Pine Trail wind Photo of Aegilops triuncialis CDFA Only a few infestations, should eradicate before it spreads
  Bladder senna
Colutea arborescens

Late May-Jun. Lower Park; Cedar Grove, Five Mile human, gravity; indehiscent Photo of Colutea arborescens Riparian, Valley Oak Woodland; Came from 1 plant in 1890s.  Control attempted in past, focused eradication program started by FOBP in May, 2003 with about 1M plants removed so far. People spread seeds by "popping" pods as they walk through the park.
  Broomsedge bluestem
Andropogon virginicus

Early Sept. Upper Park Photo of Andropogon virginicus GISD Moist to wet soil along streams, on seeps, along ponds, in pastures. Native to eastern U.S., destroying park’s wetlands. CA native species in same area–needs careful ID before removal.
  Chinese tallowtree
Sapium sebiferum

One Mile Way, between picnic 24-25 birds Photo of Sapium sebiferum TISI, TNC
  Edible fig
Ficus carica

Late Mar.-Apr. Lower, Middle and Upper Park Birds, Mammals Photo of Ficus carica Riparian, very large trees near old cabin site on Ten Mile House Rd and in former deer pen
  English ivy
Hedera helix

Mid-Sept. Lower and Middle Park Vegetative, birds Photo of Hedera helix No Ivy League Riparian, Valley Oak Woodland; mature ivy encroaching from many South Park Drive neighbors
  French broom
Genista monspessulana

Late Mar.-Jul. Middle Park by Hooker Oak Recreation Area Gravity, Water Photo of Genista monspessulana Riparian, Valley Oak, and Foothill Woodland; disturbed road edges;
  French tamarisk
Tamarix ramoissima

Early Apr.-May One plant in Upper Park upstream of Day Camp, Lindo Channel Wind Photo of Tamarix ramoissima TISI, TNC Riparian; dispersed by millions of dust-like seeds
  Giant reed, Arundo
Arundo donax

Early Oct. Lost Park, Lower and Middle Park, Lindo Channel Spread by rhizomes moved during flooding Photo of Arundo donax TISI, TNC Riparian; control underway since 2000 by City of Chico; about 110 mapped sites, roots and rhizomes tenacious. Big Chico Creek Watershed Alliance eradication project in Lindo Channel and BCC upstream of Five Mile Dam 2005-2008 appears to have killed most of the remaining arundo–needs annual monitoring & possible respraying by Park staff.
  Himalayan blackberry
Rubus armeniacus

Early May-June Lower, Middle and Upper Park Birds Mammals Photo of Rubus armeniacus TISI, TNC Riparian-Valley Oak Woodland; can be confused with native blackberry, City of Chico has used burning, Salt Creek Crews & goats for control
  Italian plumeless thistle
Carduus pycnocephalus

Mid April-June Guardian Trail, lower end of Yahi wind, humans, animals Photo of Carduus pycnocephalus TISI, TNC Grassland, Oak Woodland-three known populations–two on Guardian Trail by former BLM property, one on Yahi near start of trail
  Japanese privet
Ligustrum japonicum

Late spring-early summer Lost Park, Annie’s Glen, Camellia Way Park, Lower, Middle & Upper Park Birds Photo of Ligustrum japonicum TISI, TNC Riparian, Valley Oak Woodland; Widely planted horticultural shrub, 264 mapped sites in park, eradication underway at Five Mile & in Lower Park. As of 2009, last major infestations at golf course, area east of Caper Acres and between Crister/Madrone near Vallombrosa Ave.
  Klamath weed, St. John’s wort
Hypericum perforatum

Late April-Oct Lower, Middle and Upper Park Photo of Hypericum perforatum Grassland, Foothill Woodland
  Mediterranean hackberry
Celtis australis

Apr. Lower, Middle and Upper Park Birds Photo of Celtis australis May be the most prevalent hackberry species in Park.  Spreading rapidly from original 1900 plantings in Cedar Grove.  Major infestations on both sides of creek in this area.
  Medusahead grass
Taeniatherum caput-medusae

Late Mar. Lower, Middle and Upper Park Mammals Photo of Taeniatherum caput-medusae TISI, TNC Annual Grassland; common grass in Upper Park; can be controlled with fire and grazing; some controlled burns done by City of Chico
Olea europaea

Late May-Jun. Lower, Middle and Upper Park; old grove south of golf course Birds Photo of Olea europaea Riparian, Foothill Woodland; can form very dense canopies; spreading up canyon on both sides of creek, UC Davis research project may provide map of Upper Park locations
  Perennial pepperweed, tall whitetop
Lepidium latifolium

Early May-Sept. Lower Park Wind, Water, Animals? Photo of Lepidium latifolium TISI, TNC Riparian; roots can exceed 20 feet in depth, small infestation eradicated with herbicide at walnut orchard area in 2003, needs annual monitoring of area by park staff
Vinca major

Mid Jan.-Jul. Lower, Middle and Upper Park Vegetative Photo of Vinca major TISI, TNC Riparian, Valley Oak Woodland; forms dense sprawling mats that smother all other understory species; displaces California Grape, Native Blackberry, Pipevine, etc.
Tribulus terrestris

Early May-Oct. Lower, Middle and Upper Park Mammals (shoes and tires) Photo of Tribulus terrestris Disturbed road and trail margins; a painful nuisance to barefoot children, dogs, and troublesome to bicyclists, FOBP monitors/removes in Lower Park, Park contracts herbicide spraying along Upper Park Road
  Smooth hawthorn
Crataegus laevigata

Mid Apr. Lower, Middle & Upper Park Photo of Crataegus laevigata Need to confirm species.  Becoming prevalent in Lower and Middle Park from experimental plantings at the old Bidwell Forestry Station (now Cedar Grove) in Lower Park.  Difficult to eradicate due to root structure, large, thorny mass of woody debris to be removed
  Spanish broom
Spartium junceum

Early Mar-Jul. Upper Park Gravity Photo of Spartium junceum TISI, TNC Riparian, Valley Oak Woodland; Common and increasingly widespread on disturbed stream edges and along Hwy 32. Eradication efforts since 1995 by CNPS
  Tree of heaven
Ailanthus altissima

Late Apr.-May Lost Park, Annie’s Glen, Lower and Middle Park root sprouts, wind Photo of Ailanthus altissima TISI, TNC Riparian, Valley Oak Woodland; Increasingly common and widespread tree, FOBP eradication effort since 2005, volunteer licensed herbicide applicator uses basal bark treatment of Garlon 4–very effective if used in late summer & fall
  Western Catalpa
Catalpa speciosa

Early May Lower and Middle Park water Photo of Catalpa speciosa Riparian Woodland; FOBP mapped locations in 2007, will need permits to eradicate/revegetate by creek
  Yellow starthistle
Centaurea solstitialis

Most months Lower, Middle and Upper Park Wind Photo of Centaurea solstitialis TISI, TNC Annual Grassland, openings in Woodland; abundant and widespread; can be controlled with fire and grazing
  Plants ranked #2 on park priority list: Moderately invasive. Should provide management when possible
  Black locust
Robinia pseudoacacia

Mid April-May Lower Park, Lost Park, Annie’s Glen, Upper Park by Green Gate Gravity, water, animals? Photo of Robinia pseudoacacia TISI, TNC Widely naturalized along streams on the valley floor and in the foothills; scattered in lower coniferous forest. Native to eastern U.S.
Saponaria officinalis

Late June-Oct Upper Park Photo of Saponaria officinalis
  Bull thistle
Cirsium vulgare

Most months Upper Park Wind Photo of Cirsium vulgare Riparian areas, marshes and meadows
Anthriscus caucalis

Early March-April Lower, Middle and Upper Park People and other animals Photo of Anthriscus caucalis Should try to control in high-use areas and along trails
  Canada thistle
Cirsium arvense

Late Jul.-Sept. Wind Photo of Cirsium arvense GISD Troublesome in riparian areas, need to verify that it’s in the park
  Cheat grass, Downy brome
Bromus tectorum

Early May Lower, Middle and Upper Park Mammals, Wind Photo of Bromus tectorum TISI, TNC Annual Grassland
  Cork or rock elm
Ulmus thomasii

Cedar Grove area Photo of Ulmus thomasii Very localized infestation–need to remove many of the smaller trees, girdling will leave areas of fire-prone dead 6-8′ trees
  Eastern or common hackberry
Celtis occidentalis

Lower, Middle and Upper Park Photo of Celtis occidentalis
  European privet
Ligustrum vulgare

Early spring-early summer Lower and Middle Park Birds Photo of Ligustrum vulgare TISI, TNC

Much less prevalent than Japanese privet.  According to literature, must remove most of root system to eradicate.

  Garden (Salad) burnet
Sanguisorba minor muricata

May-August Upstream end of Upper Park Photo of Sanguisorba minor muricata

Extensive root system, need to control to prevent spread from BCCER

  Italian arum
Arum italicum

Early May Lower Park Vegetatively, corms moved by underground rodents Photo of Arum italicum Very prevalent in One Mile area especially east of Caper Acres, difficult to eradicate
  Italian thistle
Carduus tenuiflorus

Upper Park Photo of Carduus tenuiflorus
Sorghum halepense

Late May Lower and Upper Park Rhizomes Photo of Sorghum halepense TISI, TNC Moist to dry fields, orchards, lawns, roadsides, waste places. Native to Mediterranean.
  Milk thistle
Silybum marianum

Early March-June Lower Park, Upper Park by Horseshoe Lake Photo of Silybum marianum TISI, TNC Should try to eradicate in high-use areas
  Pampas grass
Cortaderia selloana

Early Sept. Lower and Middle Park Wind Photo of Cortaderia selloana GISD Riparian, Valley Oak Woodland; popular in landscaping , 2 patches at Five Mile, one along S. Park Dr., 2 locations on Vallombrosa Ave.
  Pennsylvania blackberry
Rubus pensilvanicus

Mid May-July Lower, Middle and Upper Park Photo of Rubus pensilvanicus
  Pyracantha, Chinese firethorn
Pyracantha angustifolia

Late May-Jun Lower Park Birds Photo of Pyracantha angustifolia Riparian, Valley Oak Woodland
  Red or foxtail brome
Bromus madritensis ssp. rubens

Early June Lower Park Photo of Bromus madritensis ssp. rubens TISI, TNC Native to Australia
  Silver maple
Acer saccharinum

Early Spring Lower Park Wind Photo of Acer saccharinum Widely planted street and shade tree that volunteers along creeks and river. Native to eastern N. America.
  Tall fescue
Festuca arundinacea

Mid-April Upper Park Photo of Festuca arundinacea TISI, TNC Grassland, Foothill Woodland
  Thornless (elmleaf) blackberry
Rubus ulmifolius var inermis

Early May-June Lower Park Birds, vegetatively Photo of Rubus ulmifolius var inermis Dense growth (about 30' x 150') at picnic site #8. Mentioned in Big Chico Creek Existing Conditions Report & Joe DiTomaso's Aquatic and Riparian Weeds of the West
  Tocalote, Malta starthistle
Centaurea melitensis

Late Mar.-Jul. Upper Park Wind, Mammals Photo of Centaurea melitensis GISD Annual Grassland, Foothill Woodland; occasional weed; can be confused with Yellow Star Thistle; old plants can flower in the Fall and early Winter
  Tumbleweed, pigweed
Amaranthus albus

Early May-Sept Upper Park Photo of Amaranthus albus
  Woolly or common mullein
Verbascum thapsus

Early Mar.-Oct. Lower and Upper Park Wind Photo of Verbascum thapsus TISI, TNC Riparian and disturbed areas in Woodlands; common along road edges in the County
  Plants ranked #3 on park priority list: Low to moderately invasive. Should monitor.
prunus dulcis

Mid Feb-Aprilo Lower and Middle Park squirrels Photo of prunus dulcis
  American elm
Ulmus americana

Spring Lower and Middle Park Wind Photo of Ulmus americana Widely planted street tree. It volunteers freely along Big Chico Creek, particularly on the University campus, but so far has not been found outside the urban area. Native to eastern U.S.
  Black mustard
Brassica nigra

Upper Park Photo of Brassica nigra Grassland, Foothill Woodland
  Brazilian pepper tree
Schinus terebinthifolius

Cedar Grove Photo of Schinus terebinthifolius TISI, TNC
Cinnamomum camphora

Late spring Lower Park birds Photo of Cinnamomum camphora CAIP, UoF Spreads easily by seed, can create thousands of seedlings from one tree
  Cherry or purple leaf plum
Prunus cerasifera

Late Feb-Apr. Lower, Middle and Upper Park Birds Photo of Prunus cerasifera Widely naturalized along Sacramento River and other streams from the valley floor into foothill canyons. Native to southeast Europe.
  Chinese hackberry
Celtis sinensis

Lower and Middle Park seed Photo of Celtis sinensis  
  Chinese pistache
Pistacia chinensis

Late March-April Lower, Middle and Upper Park Birds Photo of Pistacia chinensis Very common in Lower Park; may want to eradicate female trees to prevent further spreading
  Common myrtle
Myrtle communis

4th St. entrance & along Woodland birds Photo of Myrtle communis Doesn’t seem to spread very quickly
Cotoneaster franchet (?) pannosa (?)

Spring Cedar Grove   Need to determine exact species
  Field bindweed
Convolvuulas arvensis

Early April-Oct Upper Park Photo of Convolvuulas arvensis TISI, TNC Grassland
  Golden bamboo
Phyllostachys aurea

Lower Park on S. Park Dr. Wide-creeping rootstocks form solid stands Photo of Phyllostachys aurea Small patches creeping in from adjoining residence on S. Park Dr and along path from E 8th St. entrance east of Hwy 99
  Japanese honeysuckle
Lonicera japonica

Early May-June Lower Park Photo of Lonicera japonica TISI, TNC
  Mediterranean, hoary mustard
Hirschfeldia incana

Most Months Lower, Middle and Upper Park Gravity, Wind Photo of Hirschfeldia incana Annual Grassland, Riparian, Foothill Woodland; perennial weed of dry disturbed places
Lunaria annua

Mid Apr. Lower Park: CSUC Campus Gravity Photo of Lunaria annua Riparian Woodland, landscaped areas, in field east of Hwy 99 on south side of creek
  Northern California black walnut
Juglans hindsii

April-May Lower, Middle and Upper Park Mammals Photo of Juglans hindsii Riparian Woodland; no known native stands of Juglans hindsii in Butte County, widely naturalized, under consideration as invasive plant in Bidwell Park because it may significantly reduce oak regeneration
Carya illinoinensis

Spring Lower Park Squirrels, scrub jays Photo of Carya illinoinensis Escapee from cultivation. Often confused with black walnut
  Prickly lettuce
Lactuca serriola

Early April-Nov Upper Park Photo of Lactuca serriola Cal-IPC considers it an agricultural weed
  redtip photinia
Photinia x fraseri

Lower Park birds Photo of Photinia x fraseri
  Silktree, mimosa
Albizia julibrissin

summer and fall Hooker Oak, near Lower Park walnut orchard Photo of Albizia julibrissin GISD common Chico tree, spreads easily, seed viable for 50 years, should eradicate the few trees in the park to prevent spread
  Virginia creeper
Parthenocissus quinquefolia

Lower Park, north side along creekside trail birds  
  White mulberry.
Morus alba

Mid Mar-Apr. Middle and Upper Park Birds Photo of Morus alba Along streams and roads. The plant is dioecious, female trees producing blackberry-like fruits that ripen reddish to black. Native to China.  May want to eliminate female trees to prevent spread.
  Plants ranked #4 on park priority list: Invasive, but too widespread to manage
  Beardgrass, rabbit’s foot grass
Polypogon monspeliensis

Early Feb Upper Park Photo of Polypogon monspeliensis
  Bermuda grass
Cynodon dactylon

Mid May Lower, Middle and Upper Park vegetatively, seed Photo of Cynodon dactylon TISI, TNC
  Big heronbill
Erodium botrys

Early March-June Upper Park by Alligator Hole Photo of Erodium botrys Cal-IPC considers impacts to be negligible.
Lotus corniculatus

Early April-Sept Upper Park Photo of Lotus corniculatus Cal-IPC considers it to be primarily an agricultural weed.
  Birdsrape mustard
Brassica rapa

Early Dec-June Upper Park by Bear Hole Photo of Brassica rapa
  Bulbous bluegrass
Poa Bulbosa

Early March Upper Park by Brown’s Hole Photo of Poa Bulbosa
  Bur clover
Medicago polymorpha

Late Feb-June Lower, Middle and Upper Park Photo of Medicago polymorpha Prefers some shade and is most abundant under brush and trees.
Cichorium intybus

Late May-Nov Lower and Upper Park Photo of Cichorium intybus
  Creeping bentgrass
Agrostis stolonifera

Early June Middle Park by Lindo Channel Photo of Agrostis stolonifera
  Curly dock
Rumex crispus

Lower, Middle & Upper Park wind, water Photo of Rumex crispus
  Curlyleaf pondweed
Potamogeton crispus

Late May Horseshoe Lake Photo of Potamogeton crispus GISD
  Cut-leaf blackberry
Rubus laciniatus

Early May-Sept Middle Park by Lindo Channel Photo of Rubus laciniatus
  Cutleaf geranium
Geranium dissectum

Early March-June Upper Park Photo of Geranium dissectum
Paspalum dilatatum

Early May Upper Park Photo of Paspalum dilatatum
  Dovefoot geranium
Geranium molle

Early March-April Upper Park by Salmon Hole Photo of Geranium molle Cal-IPC comment" wildland impacts negligible"
  Everlasting pea
Lathyrus latifolius

Mid May-Oct Upper Park-golf course, Annie’s Glen Photo of Lathyrus latifolius
  False brome
Brachypodium distachyon

Late April Upper Park by Bear Hole Photo of Brachypodium distachyon
  Foxtail or rattail fescue
Vulpia bromoides

Early March Upper Park by Bear Hole Photo of Vulpia bromoides Cal-IPC comment:  "less common than v. myuros"
  Fragrant water lily
Nymphaea odorata

Mid May-August Horseshoe Lake Photo of Nymphaea odorata
  Hairy or winter vetch
Vicia Villosa

Early March-June Upper Park by Rod and Gun Club Photo of Vicia Villosa Cal-IPC–"widespread but minor impacts in wildlands"
  Hedgehog dogtail grass
Cynosurus echinatus

Early May Upper Park Photo of Cynosurus echinatus
Torilis arvensis

Late April-July Upper Park North Rim Photo of Torilis arvensis
  Honey locust
Gleditsia triacanthos

Lower Park-Cedar Grove, Five Mile Photo of Gleditsia triacanthos Cal-IPC–"very limited distribution"
  Hyssop loosestrife
Lythrum hyssopifolium

Early May-Sept Upper Park Photo of Lythrum hyssopifolium
  Indian or yellow sweet clover
Melilotus indica

Mid April-June Upper Park by Bear Hole Photo of Melilotus indica Cal-IPC-"present in human-disturbed habitats only"
  Italian ryegrass
Lolium multiflorum

Mid Dec. Lower, Middle and Upper Park Wind, Mammals, Water Photo of Lolium multiflorum Annual Grassland, Riparian; dominates clay soils, one of most common grasses in park
  Kentucky bluegrass
Poa pratensis ssp. Pratensis

Mid April Upper Park by Salmon Hole Photo of Poa pratensis ssp. Pratensis TISI, TNC
  Maritime beard grass
Polypogon maritimus

Early April Upper Park-Horseshoe Lake Photo of Polypogon maritimus
  Mediterranean barley
Hordeum marinum

Late March Upper Park by Rod and Gun Club Photo of Hordeum marinum TISI, TNC
  Obtuse filaree
Erodium brachycarpum

Late Dec-July Upper Park by Horseshoe Lake Photo of Erodium brachycarpum Cal-IPC-"impacts are negligible, transient"
  Orchard grass
Dactylis glomerata

Mid April Upper Park by end of Yahi Trail Photo of Dactylis glomerata
  Oysterplant, salsify
Tragopogon porrifolius

Early April-June Lower Park by Hwy 99 Photo of Tragopogon porrifolius
  Queen Anne’s lace
Daucus carota

Late April-Oct Lower Park Photo of Daucus carota TISI, TNC According to Cal-IPC-"widespread especialy on roadsides"
  Red gum
Eucalyptus camaldulensis

Early Feb. Lower, Middle and Upper Park Wind, Mammals Photo of Eucalyptus camaldulensis
  Red-stemmed filaree
Erodium cicutarium

most months Upper Park Lot P Photo of Erodium cicutarium
  Ripgut brome
Bromus diandrus

Late Feb. Lower, Middle and Upper Park Mammals, Wind Photo of Bromus diandrus Annual Grassland; common grass in Bidwell Park
  Rose clover
Trifolium hirtum

Late March-June, also early fall Upper Park Photo of Trifolium hirtum
  Russian thistle, tumbleweed
Salsola tragus

Mid June-Nov Middle Park-Lindo Channel Photo of Salsola tragus GISD
  Silver hair grass
Aira caryophyllea

Mid January Upper Park North Rim Photo of Aira caryophyllea Cal-IPC-"widespread in grasslands, impacts negligible"
  Slender wild oat
Avena barbata

Mid Jan. Lower, Middle and Upper Park Mammal, Wind Photo of Avena barbata Annual Grassland, openings in Woodland; common grass
  Smooth catsear
Hypochaeris glabra

Late Feb-July Upper Park Lot R Photo of Hypochaeris glabra
  Soft brome
Bromus hordeaceus

Late January Upper Park Photo of Bromus hordeaceus
  Spiny sowthistle
Sonchus asper

Most months Upper Park Bear Hole Photo of Sonchus asper Cal-IPC-"primarily agricultural weed"
  Subterranean clover
Trifolium subterraneum

Early March-June Upper Park E. end of Yahi Trail Photo of Trifolium subterraneum
  Tangier pea
Lathyrus tingitanus

Early Feb-July Upper Park by Bear Hole Photo of Lathyrus tingitanus
  Velvet Grass
Holcus lanatus

Mid April Upper Park Photo of Holcus lanatus TISI, TNC
  White horehound
Marrubium vulgare

Mid April-June, Sept Upper Park Photo of Marrubium vulgare
  White sweet-clover
Melilotus alba

Early March-Dec Upper Park by Rod and Gun Club Photo of Melilotus alba TISI, TNC
  White-stemmed filaree
Erodium moschatum

Late Feb-May Upper Park Photo of Erodium moschatum Cal-IPC "primarily an agricultural weed"
  Wild mustard
Sinapis arvensis

Mid Oct-May Upper Park by Day Camp Photo of Sinapis arvensis
  Wild oat
Avena fatua

Late Dec. Lower, Middle and Upper Park Mammals, Wind Photo of Avena fatua Annual Grassland, openings in Woodland; common grass
  Yellow nutsedge
Cyperus esculentus

Mid July Middle Park-Diversion Dam Photo of Cyperus esculentus
  Yellow Salsify
Tragopogon dubius

Mid March-Oct Upper Park Photo of Tragopogon dubius Cal-IPC "Generally a minor component of disturbed area"
  Plants ranked #5 on park priority list: Non-native, but do not appear to be invasive
Melissa officinalis

Early June-Sept Upper Park Photo of Melissa officinalis
  Black Cherry
Prunus serotina

Lower Park-Cedar Grove Photo of Prunus serotina
  English plantain
Plantago lanceolata

Mid April-Oct Upper Park Photo of Plantago lanceolata
  Green wattle
Acacia decurrens (arabica?) (melanoxion?)

Early Feb.-Mar. Lower Park; Cedar Grove Wind Photo of Acacia decurrens (arabica?) (melanoxion?) Riparian-Valley Oak Woodland, road edges-need to confirm species
  Japanese zelkova
Zelkova serrata

Lower and Middle Park spread by seed Photo of Zelkova serrata On Chico's approved Street Tree List, planted in Cedar Grove Forestry Station
  London plane tree
Platanus acerifolia

Late Mar.-Apr. Lower, Middle and Upper Park Wind and water Photo of Platanus acerifolia Widely naturalized along most valley and foothill streams. It may have a reproductive advantage over the native sycamore since it appears to be resistant to sycamore anthracnose, which causes die back of twigs and flowers in native sycamore.
Ranking Key
IPC: California Invasive Plant Council (Cal-IPC) Status Definitions


High-severe ecological impacts on physical processes, plant and animal communities and vegetation structure.  Most are widely distributed ecologically.

M: Moderate-substantial and apparent-but generally not severe-ecological impacts on physical processes, plant and animal communities and vegetation structure.  Moderate to high rates of dispersal; establishment generally dependent upon ecological disturbance.

Limited-invasive but their ecological impacts are minor on a statewide level or there was not enough information to justify a higher score.  Ecological amplitude and distribution are generally limited, but these species may be locally persistent and problematic.

E: Evaluated but not listed–either lack sufficient information to assign rating or available information indicates that the species does not have significant impacts at the present time.
UC: Under consideration for future List update

CA: California Dept. of Food and Agriculture Noxious Weed Ratings

B: “B” List of Noxious weeds; includes species that are more’ widespread, and therefore more difficult to contain; agency allows county Agricultural Commissioners to decide if local eradication or containment is warranted.
C: “C” List of Noxious weeds; includes species that are so widespread that the agency does not endorse state or county-funded eradication or containment efforts except in nurseries or seed lots.
Q: Temporary “A” rating pending determination of a permanent rating.
UC: Under consideration

BC: Butte County

*: Butte County’s Noxious Weed of Special Concern
Key to Control Method abbreviations:
TISI, TNC: The Invasive Species Initiative, The Nature Conservancy
Cal-IPC: The California Invasive Plant Council
CAIP, UoF: University of Florida Center for Aquatic and Invasive Plants
No Ivy League: The Ivy Removal Project (a.k.a. the No Ivy League)
GISD: Global Invasive Species Database
CDFA: California Department of Food & Agriculture

Information Sources
  • Personal observations by park users:
  • Big Chico Creek Watershed Existing Conditions Report (Big Chico Creek Watershed Alliance, 2000):
  • Butte County Department of Agriculture Weed Management Area brochure-list titled “Butte County’s Noxious Weeds of Special Concern”:
  • CalFlora Database:
  • California Department of Food and Agriculture :
  • California Invasive Plant Council 1999 rankings:
  • California State University, Chico Herbarium database-list of plants collected from Bidwell Park:
  • Chico Forestry Station and Nursery 1918 planting maps:
  • The Jepson Manual: Higher Plants of California (Hickman, J., Ed., 1993). :
  • Invasive Plants of California’s Wildlands (Bossard, C., Randall, J., Hoshovsky, M., Ed, 2000):
  • Lost Arboretum: Name Changes and Other Information (Wes Dempsey, distributed at February 22, 2004 walk) :
  • Proposed Annie Bidwell Trail Botanical Resource Assessment (California State University Research Foundation, 2000):
  • A Resource Inventory of Upper Bidwell Park Expansion Area (California State University Research Foundation, 2000) :
  • Selected Plants of Northern California (Vernon Oswald, 2002):
  • Survey for Special Status Botanical Species for the City of Chico’s Bidwell Park Trails Project (Kristiaan Stuart, 2002):
  • Vascular Plants of Upper Bidwell Park (Vernon Oswald, 1986) :
  • Vascular Plants of Butte County (Vernon Oswald, 1994):

Most species nomenclature follows The Jepson Manual: Higher Plants of California
(Hickman, J., Ed., 1993). Common Names and additional information follows
Selected Plants of Northern California and Adjacent Nevada (Oswald, V. 2002)

Bidwell Park Invasive Plant Watch List

To date, these plants have not been identified in Bidwell Park. However, they are considered
very invasive in nearby areas and should be added to the Priority 1 list if or when they are found
in the park.

Common Name
Scientific Name
Reason for Inclusion Photo
Control Method
(no common name)
Myoporum laetum
On Cal-IPC Invasive Trees of Central CA Photo of Myoporum laetum Cal-IPC
Artichoke thistle, Cardoon
Cynara cardunculus
Found in other local watersheds Photo of Cynara cardunculus
Black acacia
Acacia melanoxylon
On Cal-IPC Invasive Trees of Central CA Photo of Acacia melanoxylon GISD
Carob tree
Ceratonia siliqua
seeds spread easily Photo of Ceratonia siliqua
Creeping water primrose
Ludwigia uruguayeniss
On Butte County’s invasive plant list Photo of Ludwigia uruguayeniss
Diffuse knapweed
Centaurea diffusa
On Butte County’s invasive plant list Photo of Centaurea diffusa TISI, TNC
Hoary cress
Cardaria draba
On Glenn County’s invasive plant list Photo of Cardaria draba
Japanese dodder
Cuscuta japonica choisy
Cultural uses for plant indicate it may be in Butte County  
Parrot Feather
Myriophyllum aquaticum
On Butte County’s invasive plant list Photo of Myriophyllum aquaticum GISD
Peruvian pepper tree
Schinus molle
On Cal-IPC Invasive Trees of Central CA Photo of Schinus molle
Plumeless thistle
Carduus acanthiodes
On Glenn County’s invasive plant list Photo of Carduus acanthiodes
Purple loosestrife
Lythrum salicaria
On Butte County’s invasive plant list Photo of Lythrum salicaria TISI, TNC
Purple starthistle
Centaurea calcitrapa
On Glenn County’s invasive plant list Photo of Centaurea calcitrapa
Rush skeletonweed
Chondrilla juncea
On Butte County’s invasive plant list Photo of Chondrilla juncea
Russian olive
Elaeagnus angustifolia
On Cal-IPC Invasive Trees of Central CA Photo of Elaeagnus angustifolia TISI, TNC
Scarlet wisteria
Sesbania punicea
at Lake Oroville-Red Alert Photo of Sesbania punicea TISI, TNC
Scotch broom
Cytisus scoparius
Found in other local watersheds Photo of Cytisus scoparius TISI, TNC
Slender false-brome
Brachypodium sylvaticum
Problem in areas further north Photo of Brachypodium sylvaticum
Spotted knapweed
Centaurea maculosa
On Butte County’s invasive plant list Photo of Centaurea maculosa TISI, TNC
Dittrichia graveolens
Cal-IPC 2008 Symposium alert  
White horsenettle
Solanum elaeagnifolium
On Glenn County’s invasive plant list Photo of Solanum elaeagnifolium
Wild fennel
Foeniculum vulgare
Found nearby, very invasive in other areas Photo of Foeniculum vulgare TISI, TNC