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Parthenium confertum var. microcephalum

(Grays Feverfew)

Interesting Facts

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Common Names

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Common Names in English:

Grays Feverfew, Gray's Feverfew

Description

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Family Compositae

The largest family of flowering plants , the Compositae (Asteraceae), comprising about 1,100 genera and more than 20,000 species and characterized by many small flowers arranged in a head looking like a single flower and subtended by an involucre of bracts. A head may consist of both ray flowers and disk flowers, as in the sunflower, of disk flowers only, as in the burdock, or of ray flowers only, as in the dandelion.

Tribe Heliantheae

The Heliantheae are a tribe of closely related genera of the sunflower family that can be readily recognized due to the association of a receptacular bract or chaff scale with each disk floret in the head . The heads usually include bisexual , actinomorphic disk florets with tubular corollas that have 4 or 5 distal lobes and also peripheral zygomorphic female or sometimes sterile florets with strap-shaped corollas that have 3 or fewer distal teeth. However, the ray flowers are sometimes absent and the heads are then discoid , containing only bisexual florets with tubular corollas. The pappus is absent or more commonly ranges from scales to stiff bristles . -- Gerald Carr.

Genus Parthenium

Annuals , biennials, perennials , subshrubs , or shrubs [treelets], 1-120[-400] cm. Stems ± erect , usually branched. Leaves usually cauline, sometimes in rosettes; alternate; petiolate or sessile; blades elliptic , lanceolate, linear , lyrate, oblanceolate , obovate , ovate , rounded-deltate, spatulate , sometimes (1-) 2-pinnately lobed , ultimate margins entire or toothed , faces usually hairy and gland-dotted (at least the abaxial ). Heads usually radiate , sometimes ± disciform (P. alpinum), usually borne in corymbiform or paniculiform arrays (in glomerules in P. argentatum, borne singly in P. alpinum and P. ligulatum). Involucres ± hemispheric [rotate], 3-8(-12+) mm diam. Phyllaries falling, 10(-16) in 2 series, usually distinct (partially connate in P. alpinum), outer 5(-8) herbaceous to scarious , inner 5-8 ± scarious to membranous. Receptacles flat to conic; paleae cuneate to flabelliform, scarious or membranous, distally papillate and/or fimbrillate , all or the peripheral each ± enfolding a disc floret . Ray (pistillate ) florets 5(-8), fertile ; corollas ochroleucous , tubes stout, glandular , laminae oblong to reniform or orbiculate, or ± coroniform (none in P. alpinum). Disc florets 12-60+, functionally staminate ; corollas ochroleucous, funnelform , lobes 5 (filaments distinct, anthers connate). Cypselae (black) oblanceoloid, obovoid , or pyriform , often ± obcompressed (shed together with subtending phyllary and 2 contiguous disc florets and their investing paleae) ; pappi 0 (shoulders of cypselae may bear 1-3 pappus-like, triangular to ovate, or ± subulate enations ). x = 9.

Species ca. 16: New World, mostly warm-temperate and tropical , some temperate ; introduced in Old World.[1]

Taxonomy

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Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 15-Mar-2000

Similar Species

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Members of the genus Parthenium

ZipcodeZoo has pages for 26 species, subspecies, varieties, forms, and cultivars in this genus:

P. alpinum (Alpine Fever-Few) · P. argentatum (Guayule) · P. confertum (Gray Feverfew) · P. confertum Gray var. divaricatum Rollins (Gray's Feverfew) · P. confertum Gray var. intermedium Mears, var. nov. ined. (Gray Feverfew) · P. confertum Gray var. lyratum (Gray) Rollins (Gray's Feverfew) · P. confertum Gray var. microcephalum Rollins (Gray's Feverfew) · P. confertum var. confertum (Gray's Feverfew) · P. confertum var. divaricatum (Grays Feverfew) · P. confertum var. intermedium (Grays Feverfew) · P. confertum var. lyratum (Grays Feverfew) · P. confertum var. microcephalum (Grays Feverfew) · P. hysterophorus (False Ragweed) · P. incanum (Mariola) · P. integrifolium (American Fever-Few) · P. integrifolium var. auriculatum (Wild Quinine) · P. integrifolium var. auriculatum (Britton) Cornelius ex Cronq. (Glade Wild Quinine) · P. integrifolium var. henryanum (Wild Quinine) · P. integrifolium var. hispidum (Wild Quinine) · P. integrifolium var. hispidum (Raf.) Mears (Wild Quinine) · P. integrifolium var. integrifolium (Wild Quinine) · P. integrifolium var. mabryanum (Wild Quinine) · P. integrifolium var. mabryanum Mears (Mabry's Wild Quinine) · P. ligulatum (Colorado Feverfew) · P. matricaria (Feverfew) · P. tetraneuris (Arkansas River Feverfew)

More Info

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Further Reading

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Notes

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Contributors

Identifiers

Footnotes

  1. John L. Strother "Parthenium". in Flora of North America Vol. 21 Page 8, 9, 20. Oxford University Press. Online at EFloras.org. [back]
Last Revised: 7/21/2012