Plant native species in your garden. Spotted knapweed prefers to grow on well-drained, light to coarse soil and does not tolerate dense shade or constant moisture. Invasive plants are often spread accidentally from seeds stuck in treads. For example, it releases a chemical that hinders native plants’ root growth and displaces vegetation. Leaves become smaller as they advance up the stem; heads of pink to purple (sometimes white) flowers grow at the ends of the branches; excluding flowers, the heads are about 1/4\" in diameter by 1/2\" tall. Dumping yard waste in natural areas can introduce invasive species, which can thrive and spread. Also, infestations can decrease food quantities for wildlife and livestock. Even leaf piles can be problematic, as dumped piles can smother native vegetation. Spotted knapweed only reproduces by seed. As spotted knapweed seeds mature in late summer and fall, they can be spread on mowing equipment and in infested hay, seed, and gravel, or by hitchhiking on vehicles, other equipment, and even clothing. The diversity of nonwoody vascular plants is staggering! spotted knapweed can increase runoff and erosion, leading to sedimentation of watercourses. They can also spread by wind and water. The whole Centaurea genus is named after Chiron the centaur who was the legendary first healer. Visit our FAQ page. In a few years it can overtake and replace pasture grasses, native plants, and even other aggressive weeds such as sericea lespedeza. Unlike the other knapweed species, the base of the spotted knapweed’s flowers has black tips, making it appear spotted. There are five invasive knapweed species in Canada, unintentionally introduced from Europe in the late 1800s. Southern, north-central, and eastern Missouri. For example, it is estimated that Montana loses 4.5 million dollars annually in recreation, forage, and costs related to knapweed control. Flowers: The flowers are light purple, aromatic, and found individually or in clusters on the stems. There is no evidence at this time to show that spotted or diffuse This plant produces chemicals that inhibit nearby plants, reducing diversity in the area and degrading wildlife habitat. A large, conspicuous insect, it lays its eggs on the top of the knapweed's root crown. In Montana knapweed was actually spread on purpose by airplane by beekeepers as it is an excellent honey plant. Seeds and plant fragments make their way into … Its leaves are slightly hairy and decrease in size towards the top of the stem. In Geoffrey Chaucer’s day, this plant was called Matfellon and was used with pepper to stimulate the appetite. Cattle and other animals avoid eating it so it can cause large reductions in available food for grazing animals. A taprooted, short-lived perennial named for the spotted bracts immediately below the many lavender flowers. Diffuse Knapweed ( Centaurea diffusa ) also grows a single, branched stem from a similar looking rosette. Spotted knapweed is a perennial with several branched upright stems growing from a stout taproot; usually to 5 feet tall. Spotted knapweed is a native of Europe and Asia. In past times, young women wore spotted knapweed flowers to … Spotted knapweed has few natural enemies and is not preferred by livestock as forage. Biological control insects are used to help manage this plant. Cutting or pulling before flowering can be good for small infestations to stop seed production, but requires many years to completely eliminate. Previous work, using an activated carbon experiment, suggests allelopathic effects by spotted knapweed on native bunchgrasses (Ridenour and Callaway 2001). It is often found in heavily disturbed sites, such as roadsides, gravel pits, and edges of agricultural fields, but it moves from those areas into undisturbed pastures, dry prairies, oak and pine woodlands, and rangeland. Displacement of native vegetation may impact biodiversity. Upright stems are branched at the top and the stems are ribbed, and sometimes as … Local Concern: Spotted knapweed is poisonous to other plants, creating barren areas where only knapweed grows. Spotted knapweed is a very aggressive species that can quickly infest large areas. Producing branched stems reductions in available food for grazing animals infestations can decrease food quantities for and. Sheep and goats are useful biological controls of Russian knapweed as they are unaffected by Nature., open forests and along roadsides in recreation, forage, and produces mature seeds July! Alfalfa and clover seeds your garden twice as beautiful or bicycle tires when moving between designated trails in areas... 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