Russian knapweed | |
---|---|
![]() | |
Scientific classification ![]() | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Asterales |
Family: | Asteraceae |
Tribe: | Cardueae |
Genus: | Rhaponticum |
Species: | R. repens |
Binomial name | |
Rhaponticum repens | |
Synonyms [1] | |
|
Rhaponticum repens, synonyms including Acroptilon repens and Leuzea repens, [1] with the common name Russian knapweed, is a species of bushy rhizomatous perennial, up to 80 cm tall. Stems and leaves are finely arachnoid-tomentose becoming glabrous and green with age. The rosette leaves are oblanceolate, pinnately lobed to entire, 2–3 cm wide by 3–8 cm long. The lower cauline leaves are smaller, pinnately lobed; the upper leaves become much reduced, sessile, serrate to entire. The heads are numerous terminating the branches. Flowers are pink to purplish, the marginal ones not enlarged. The outer and middle involucral bracts are broad, striate, smooth with broadly rounded tips; the inner bracts are narrower with hairy tips. Pappus present with bristles 6–11 mm long. Fruit is a whitish, slightly ridged achene.
Russian knapweed is a deep-rooted long-lived perennial. Some stands have been in existence for 75 years. It forms dense colonies in cultivated fields, orchards, pastures, and roadsides.
A native to Eurasia, Russian knapweed was introduced into North America in the late 19th century. Absent only from southeastern U.S., it has become widespread in other regions, especially in the western United States. [2]
Nigropallidal encephalomalacia, also called chewing disease, a movement disorder similar to Parkinson's disease, is caused in horses ingesting Russian knapweed for prolonged periods. A sesquiterpene lactone, repin, in the plant is likely responsible for this toxicity. [3]
The species was first described by Carl Linnaeus in 1763 as Centaurea repens. [4] [5] [6] Augustin Pyramus de Candolle separated it from the genus Centaurea in 1838, placing it in the genus Acroptilon. [5] The genus name derives from acro- (high, here meaning tip) and ptilo- (feather). [7] A 1995 molecular phylogenetic study, the structure of the flower, and the chromosome number support separating it from the genus Centaurea . Some sources then continue to place it as the sole member of the monotypic genus Acroptilon. [7] A phylogenetic study published in 2006 concluded that Acroptilon belongs in the genus Rhaponticum. [8]
Asteraceae is a large family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the order Asterales. The number of species in Asteraceae is rivaled only by the Orchidaceae, and which is the larger family is unclear as the quantity of extant species in each family is unknown. The Asteraceae were first described in the year 1740 and given the original name Compositae. The family is commonly known as the aster, daisy, composite, or sunflower family.
Centaurea is a genus of over 700 species of herbaceous thistle-like flowering plants in the family Asteraceae. Members of the genus are found only north of the equator, mostly in the Eastern Hemisphere; the Middle East and surrounding regions are particularly species-rich.
Centaurea scabiosa, or greater knapweed, is a perennial plant of the genus Centaurea. It is native to Europe and bears purple flower heads.
Gerbera L. is a genus of plants in the Asteraceae (Compositae) family. The first scientific description of a Gerbera was made by J. D. Hooker in Curtis's Botanical Magazine in 1889 when he described Gerbera jamesonii, a South African species also known as Transvaal daisy or Barberton daisy. Gerbera is also commonly known as the African daisy.
Jacobaea maritima, commonly known as silver ragwort, is a perennial plant species in the genus Jacobaea in the family Asteraceae, native to the Mediterranean region. It was formerly placed in the genus Senecio, and is still widely referred to as Senecio cineraria; see the list of synonyms (right) for other names.
Yermo xanthocephalus commonly known as the desert yellowhead is an American flowering plant endemic to southern Wyoming. It is the only member of the genus Yermo and was first described in 1991.
Wachendorfia is a genus of perennial herbaceous plants that is assigned to the bloodroot family. The plants have a perennial rootstock with red sap. From the rootstock emerge lance- or line-shaped, sometime sickle-shaped, pleated, simple leaves set in a fan, that are flattened to create a left and right surface rather than an upper and lower surface. The leaves die when the seeds are shed in three of the species, and are perennial in one species.
Rhaponticum is a genus of flowering plants in the tribe Cardueae within the family Asteraceae. As of November 2023, it is accepted by Plants of the World Online, but rejected by the Global Compositae Database in favour of Leuzea.
Centaurea virgata is a species of Centaurea. It is native to Western Asia. The subspecies C. virgata subsp. squarrosa is known as squarrose knapweed.
Centaurea nigra is a species of flowering plant in the family Asteraceae known by the common names lesser knapweed, common knapweed and black knapweed. A local vernacular name is hardheads.
Limnophila is a genus of flowering plants in the family Plantaginaceae. It is distributed in tropical and subtropical regions of Africa, Asia, Australia, and the Pacific Islands. Species are known commonly as marshweeds.
Hymenonema is a genus of flowering plants in the family Asteraceae endemic to Greece. On each of the single or few stems, the species have one to three flowerheads consisting of yellow or yolk yellow ligulate florets, scaly pappus, greyish, pinnately segmented leaves in a basal rosette, and few smaller leaves on the 20–70 cm high stems. It contains two species: Hymenonema graecum, that is known from the Cyclades, and Hymenonema laconicum, which occurs in the central and south-eastern Peloponnesos.
Rhaponticum scariosum, common name giant scabiosa, is a perennial herbaceous flowering plant of the genus Rhaponticum of the family Asteraceae.
Rheum rhaponticum, the false rhubarb, rhapontic rhubarb or rhapontic, is a plant species in the genus Rheum found in the wild. It is the only Rheum species found only in Europe, and is now restricted to the Rila mountain range in south-western Bulgaria. It was introduced to other countries in Europe. It is considered to be one of the parents of the modern culinary rhubarb.
Balsamorhiza hookeri is a North American species of perennial plant in the family Asteraceae. It grows in the Great Basin and neighboring regions in the Western United States. It is found in Washington, Oregon, California, Idaho, Nevada, Utah, and Arizona.
Cirsium altissimum is a North American species of plants in the tribe Cardueae within the family Asteraceae. Common names are tall thistle or roadside thistle. The species is native to the eastern and Central United States.
Hymenonema graecum is a perennial herbaceous plant of 20–70 cm, that rests with its buds at or just under the surface of the soil. The Greek vernacular name is Αδραλίδα (Adralida), meaning "handsome Lida". The leaves are pinnate, and may be up to 1 cm wide. The ligulate flowers are yellow. The species is an endemic of Greece.
Hymenonema laconicum is a species of herbaceous perennial plant in the Asteraceae family. It is small to average height, with a rosette of greyish pinnately segmented leaves, and little branching solid stems carrying one to three heads of orange or yolk yellow ray-flowers, with a purple anther tube, and scaly pappus. The species is an endemic of the central and south-eastern Peloponnesos, and flowers in May and June.
Nigropallidal encephalomalacia or Chewing disease is a neurological condition that affects horses that have eaten certain toxic plants. Affected animals are unable to prehend food because of lip and tongue paralysis, and may appear to keep their jaws open with the tongue protruded because of reduced jaw tone. Some horses may appear to show their upper teeth because of increased hypertonicity of the facial and upper lip muscles. Other animals may show severe depression and carrying their heads low. Because poisoned horses are unable to eat, these animals become weakened and ultimately die of starvation.
Meadow knapweed, also known as hybrid knapweed or protean knapweed, is a fertile hybrid between black knapweed and brown knapweed. The taxonomic status of the species is uncertain, and meadow knapweed has been variously described as different species.