Silphium perplexum | |
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Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Asterids |
Order: | Asterales |
Family: | Asteraceae |
Genus: | Silphium |
Species: | S. perplexum |
Binomial name | |
Silphium perplexum J.R.Allison, 2001 | |
Silphium perplexumJ.R.Allison is a prairie species in the Asteraceae endemic to the state of Alabama. S. perplexum is commonly known as Old Cahaba rosinweed, a reference to the Cahaba River near which all populations of this species are found.
The specific epithet 'perplexum' means perplexing. [1]
Old Cahaba rosinweed was described in 2001 by the botanist James Robert Allison. [2] The species is thought to have arisen from a hybridization event between Silphium integrifolium Michx. the entire leaf rosinweed and Silphium glutinosumJ.R.Allison. the sticky rosinweed. This conclusion was originally based on similarities in the morphology of S. perplexum compared with its putative parent species. In most cases, the morphological characters of S. perplexum are intermediate between that of the parent species [3] Despite S. perplexum having arisen from a hybridization event, it is not appropriate to treat it as a mere hybrid as its distribution does not overlap with either of its parent species. From this it can be concluded that the species is self-sustaining. This means that its existence and future evolution are independent of the fate of its parent species. Furthermore, if Old Cahaba rosinweed were to be characterized as a subspecies or even a variety, this would necessitate choosing if it had more similarities with S. glutinosum or S. integrifolium. At present there is not a clear basis for selecting one over the other. To conclude, because populations of S. perplexum vary little in their morphology, are easy to distinguish from the parent species and occupy non-overlapping areas, there is a strong consensus that S. perplexum is a legitimate species. [4] The ‘lifespan’ of this species (e.g., how long it has existed with few new additions from interspecific hybridization events) has been estimated by studying its distribution compared with its putative parents. Evidence suggests the species could not have formed post 1885 but no lower bounds on its origin have been proposed, therefore its age is uncertain. [3] Tracing the ancestry of S. perplexum is complicated due to it being of hybrid origin. However, the phylogeny of the Silphium genus, including of one of its parent species 'S. integrifolium' (the prairie rosinweed) is understood. S. integrifolium shares a clade with S. wasiotense and S. perfoliatum whilst being more distantly related to S. mohrii . [5]
Silphium perplexum is a herbaceous perennial growing to a height of 8 ft (2.4 m), it has short rhizomes. Leaf morphology changes as the plant develops with basal rosette leaves differing from stem leaves. Stem leaves are around 30 cm long and are arranged alternately up the stem. Stem leaves are variable being either ovate or lanceolate, they may attach to the stem directly with auriculate leaf bases. Alternatively, leaves may have short petioles with winged margins resembling leaflets. The leaf margins are usually smooth but may be dentate. Almost the entire above ground surface of the plant is covered in glandular and pubescent trichomes. Glandular trichomes are branched and amber colored, the glands secretions give the plant a resinous texture. [6] Old Cahaba rosinweed has 'stipulate glandular trichomes' which are infrequently found in Silphium except for species such as S. laciniatum and the parent species of S. perplexum, S. glutinosum. [7] This plant develops a basal rosette during its juvenile phase, however, basal leaves are usually lost by the time of flowering. At maturity, stems from one to eight feet are produced which do not branch below the inflorescences. [6] Silphium perplexum flowers from July to October, their flowers are produced in much branched open panicles with each stem holding as many as thirty. The flowers are composite, containing a cluster of fertile disk-florets surrounded by many bright yellow ray-florets averaging around 20 per inflorescence. After pollination, simple dry-fruit are produced, the fruit are characterized as a cypsela along with the fruit of all other Asteraceae. Despite this, they are often incorrectly described as achenes. [8] Old Cahaha rosinweed is often confused with its commoner parent species S. glutinosum. This is due to similarities in their morphology, such as the presence of glandular trichomes on the involucral bracts, leaves and stems. In spite of the similarities, S. perplexum differs from S. glutinosum in several ways. Firstly, S. perplexum has taller stems with more numerous nodes, its leaves are also more lanceolate with shorter petioles and larger blades. Also, flower heads are more elongated and the bracts surrounding the flowers have a more chartaceous (papery) texture. Each flower of S. perplexum contains a greater number of ray-florets than in S. glutinosum and they are of a deeper yellow. [3]
Silphium perplexum can reproduce vegetatively through rhizome growth though the rhizomes are short, so spread slowly. Alternatively, this species can produce large numbers of seeds which are released when the seed heads shatter in autumn. S. perplexum commonly cross-pollinates with other Silphium species in natural environments so is liable to produce hybrid offspring. Hybrids observed include S. anteriscus x S. perplexum. [3]
This species is endemic to only three counties in west-central Alabama, it has an extremely limited distribution with all populations less than 9 miles from the Cahaba River. [6] Old Cahaba rosinweeds favor soils overlying chalk, [3] this contrasts with the parent species S. glutinosum which prefers growing over dolomite or limestone. S. perplexum is most numerous in prairies and openings within scrub and forest. This species is found alongside other tallgrass-prairie plants including grasses such as Andropogon L. spp. and Schizachyriumscoparium (Michx.) Nash. as well as legumes including Desmanthus illinoensis (Michx.) MacMill. ex B.L.Rob. & Fernald. and shrubs including Rosa bracteata J.C.Wendl. [8]
Due to this species very restricted range and low population numbers within Alabama it has been listed as an S1 species by ‘Nature serve’. This means that Silphium perplexum is at a high probability of extinction unless conservation action is taken. [9] Despite the recognized threats to this species, S. perplexum is not listed on the U.S. Endangered Species act [10] or the IUCN red list. [11] The lack of conservation attention could be due to uncertainty surrounding S. perplexum's species status.
Silphium is a genus of North American plants in the tribe Heliantheae within the family Asteraceae.
Silphium laciniatum is a species of flowering plant in the family Asteraceae known commonly as compassplant or compass plant. It is native to North America, where it occurs in Ontario in Canada and the eastern and central United States as far west as New Mexico. Other common names include prairie compass plant, pilotweed, polarplant, gum weed, cut-leaf silphium, and turpentine plant. It is a rosinweed of genus Silphium.
Cahaba may refer to:
Echinacea angustifolia, the narrow-leaved purple coneflower or blacksamson echinacea, is a species of flowering plant in the family Asteraceae. It is native to North America, where it is widespread across much of the Great Plains of central Canada and the central United States, with additional populations in surrounding regions.
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Eurybia is a genus of plants in the family Asteraceae that were previously included in the genus Aster. Most species are native to North America, although one is also present in northern Eurasia. There are 23 species in the genus, including 1 natural hybrid. The name was first applied by Alexandre de Cassini in 1820. The name is derived from Ancient Greek εὐρύς (eurús), meaning "wide", and βαιός (baiós), meaning "few", perhaps in reference to the small number of relatively wide ray florets.
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Silphium perfoliatum, the cup plant or cup-plant, is a species of flowering plant in the family Asteraceae, native to eastern and central North America. It is an erect herbaceous perennial with triangular toothed leaves, and daisy-like yellow composite flower heads in summer.
Calycadenia multiglandulosa is a species of flowering plant in the family Asteraceae, known by the common names sticky calycadenia and sticky western rosinweed. It is endemic to California, where it is a common in the Coast Ranges and in the Sierra Nevada Foothills from Shasta County to Kern County.
Calycadenia spicata is a species of flowering plant in the family Asteraceae known by the common name spiked western rosinweed. It is endemic to central California, where is a common grassland plant in the Central Valley and adjacent Sierra Nevada foothills from Butte County to Kern County.
Warionia is a genus in the tribe Cichorieae within the family Asteraceae. The only known species is Warionia saharae, an endemic of Algeria and Morocco, and it is locally known in the Berber language as afessas, abessas or tazart n-îfiss. It is an aromatic, thistle-like shrub of ½–2 m high, that contains a white latex, and has fleshy, pinnately divided, wavy leaves. It is not thorny or prickly. The aggregate flower heads contain yellow disk florets. It flowers from April till June. Because Warionia is deviant in many respects from any other Asteraceae, different scholars have placed it hesitantly in the Cardueae, Gundelieae, Mutisieae, but now genetic analysis positions it as the sister group to all other Cichorieae.
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Parthenium integrifolium is a species of flowering plant in the family Asteraceae known by the common names wild quinine, American feverfew, and eastern feverfew. It is native to the eastern and midwestern United States.
Silphium mohrii, known by the common names Mohr's rosinweed and shaggy rosinweed, is a species of flowering plant in the family Asteraceae. It is native to the Southeastern United States, where it is native only to northern Alabama, southern Tennessee, and extreme northwest Georgia. It is native to prairie remnants and rocky limestone openings. Because of its restricted range and severely declined habitat, it is considered a vulnerable species.
Astranthium integrifolium, the entireleaf western daisy or eastern western-daisy, is a North American species of flowering plants in the family Asteraceae. It is native to the east-central part of the United States primarily the Cumberland Plateau and Ohio/Tennessee Valley. It is found in the States of Tennessee, Kentucky, Alabama, and Georgia, with isolated populations in Mississippi and West Virginia.
Silphium terebinthinaceum is a member of the Asteraceae, a family that includes sunflowers, and is commonly referred to as prairie dock or prairie rosinweed. It is native to central and eastern North America. "Rosinweed" became one of the plant's common names due to the fact that upon injury, resin flows from the wound, giving the plant a sweet smell. Tea brewed from the roots of the prairie dock have a variety of medical applications in Native American culture. The smoke from this plant has also been used as a treatment for congestion and rheumatism.
Silphium trifoliatum, commonly known as whorled rosinweed, is a species of flowering plant in the family Asteraceae. It is native to the eastern United States, where it is found east of the Mississippi River. Its natural habitat is open, grassy areas such as prairies, river cobble bars, and roadsides. It is a tall perennial that produces heads of yellow flowers in mid-summer through fall.
Silphium radula, commonly known as roughstem rosinweed, is a species of flowering plant in the family Asteraceae. It is native North America, where it is found in the South Central region of the United States. Its natural habitat is prairies over sandy or calcareous soil.
Silphium integrifolium is a species of flowering plant in the family Asteraceae. Its common names include rosinweed, whole-leaf rosinweed, entire-leaf rosinweed, prairie rosinweed, and silflower. It is native to eastern North America, including Ontario in Canada and the eastern and central United States as far west as New Mexico.
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