The Wisconsin State Herbarium and Department of Natural Resources maintain a develop listing of invasive industrial plant species that includes detailed descriptions and locations of harmful plant found throughout the state . There are about 37 plant on Wisconsin ’s trespassing plant species list , but only four of these most serious invaders have thorn .

Multiflora Rose (Rosa multiflora)

The multiflora rose is an invasive alien plant found in exposed Grant Wood and grassland in southern Wisconsin that was first planted in the state to ascertain soil wearing . This plant forms dense tangles of stems that bear needlelike thorns , making it baffling to see . Established both by bird - carried seed and vegetative public exposure , the multiflora rose has clean , star - shaped bloom and orange - red Chuck Berry - like yield . The baby rose rose acquire in a clumping , bush - similar manner , with compound leafage comprised of unremarkably seven ellipse - shape leaflets . The tall , curve stems are covered with stout , pointed irritant .

Autumn Olive (Elaeagnus umbellata)

The autumn European olive tree is an trespassing tree found invading unbalanced sites in southern Wisconsin that was first brought to the land as an ornamental tree . The fall olive has twigs and undersides of leafage that are covered with silvern scale , as well as twigs with long , thin thorns . This invasive tree diagram has simple leaves with quiet edges that grow in an alternately arranged fashion along the branches . The fall olive blooms in early summertime with yellowish , elongated blossom and bear clustered , berry - like ruddy fruit . The Russian olive ( Elaeagnus angustifolia ) is very similar to the fall olive , but it often does n’t have thorn on the branchlet . Another distinguishing characteristic is that the Russian European olive tree tree diagram bring about silvery , dry fruits alternatively of red , juicy berries .

Japanese Barberry (Berberis thunbergii)

The Japanese barberry is a thorny , invasive shrub that grows in timberland , line of business and abandoned grazing land throughout most of Wisconsin . Native to Asia , the Japanese barberry was first bring in to Wisconsin as an ornamental shrub . The Japanese barberry produce up to about 3 ½ foot tall and has sharp , stiff pricker , up to 1/3 - inch long , growing beside its bud . Its whitish to pale - yellow flowers have six petals and bloom in May , followed by stretch red berries that ride out on the arm until November . The Nipponese barberry has simple-minded , spatula - mould farewell that are alternately set along the branches and flock in pairs or group of up to six leaves right above each thorn .

Black Locust (Robinia pseudoacacia)

The ignominious locust tree is an encroaching tree that is find in southerly Wisconsin but also on disturbed internet site in the northerly part of the state . The black locust tree has couple of stout prickle at each folio bud and compound leaves comprised of 15 leaflet . The black locust tree flower during give and summertime in little white , fragrant flowers , followed by brownish - purple seed pods .

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