], 10-120(-350+) cm. Stems usually erect
, branched mostly distally (spreading
and branched throughout in C.
, or strigose
. Leaves basal and cauline (mostly cauline at flowering) ; alternate; petiolate
or sessile; blades
mostly lanceolate to oblanceolate
or entire, faces
usually hispid, hispidulous, strigillose, or strigose (eglandular
). Heads radiate
, usually in spreading to strict
arrays (borne ± singly in C. ramosissima). Involucres ± turbinate
, 2-5[-7+] mm diam. Phyllaries 20-40+ in 2-4 series, appressed
in fruit), the larger usually 3-nerved (midnerves
orange to brownish; not notably keeled
), lanceolate to linear, unequal, ± herbaceous medially, margins membranous, abaxial
faces glabrous or hirsutulous
, hispidulous, or strigose. Receptacles ± flat, pitted
, epaleate. Peripheral ("ray") florets pistillate
: either 20-45+ in 1-2+ series, corollas white to purplish (filiform
filiform to elliptic
, 0.1-1[-1.5+] mm), or 20-150+ in 2-5+ series, corollas ochroleucous
(filiform, laminae lacking, distally truncate or 2-5-toothed). Disc florets 3-30+, bisexual
, fertile; corollas yellowish (nerves
sometimes prominently resinous
shorter than narrowly funnelform
5, erect or spreading, deltate; style-branch appendages
deltate. Cypselae compressed
to elliptic, 1-nerved on each edge
, faces glabrous or strigillose (hairs
0.05-0.1+ mm), eglandular; pappi persistent
, of 15-25+ pinkish, sordid
, or white, ± equal, barbellulate
, apically attenuate bristles
in 1 series. x = 9.
Species 25-40+: widespread, mostly in subtropical and warm-temperate zones.
Distinctions between Conyza and Erigeron, as usually circumscribed in the past 50+ years, are not always clear. Usually, conyzas have unequal (graduated ) phyllaries and 2-20+ times as many pistillate florets as bisexual florets in each head (rarely more bisexual than pistillate), and corollas of pistillate florets either lack laminae or have laminae usually less than 1(-1.5) mm. Erigerons usually have subequal phyllaries and more bisexual than pistillate florets (rarely more pistillate than bisexual) and corollas of pistillate florets (if any) usually have laminae 2-10+ mm.
In studies by R. D. Noyes (2000) and by Noyes and L. H. Rieseberg (1999), Conyza, as traditionally circumscribed, was found to be nested within Erigeron and to be para- and/or polyphyletic. Here, absent an alternate taxonomy, four species traditionally treated in Conyza are retained in Conyza and a separate suite of six species that have usually been included in Conyza are treated in Laënnecia.
Status: Accepted Name
Comment: Data Providers: Govaerts World Compositae Checklist A-G, IPNI, Tropicos. GCC LSID: urn :lsid:compositae.org:names:597F5DC9-128A-4AC6-93B3-B6F41E020BFF
Last scrutiny: 12-Aug-09
Members of the genus Conyza
ZipcodeZoo has pages for 16 species, subspecies, varieties, forms, and cultivars in this genus:
C. albida (Broad-Leaved Fleabane) · C. anthelmintica (Ironweed) · C. apurensis (Manzanilla Horseweed) · C. balsamifera (Nagi Camphor) · C. bilbaoana (Fleabane) · C. bonariensis (Asthmaweed) · C. bonariensis var. bonariensis (Asthmaweed) · C. britannica (Xuan Fu Hua) · C. canadensis (Canada Horseweed) · C. canadensis var. canadensis (Canadian Horseweed) · C. canadensis var. glabrata (Canadian Horseweed) · C. canadensis var. pusilla (Canadian Horseweed) · C. floribunda (Asthmaweed) · C. primulifolia (Primroseleaf Horseweed) · C. ramosissima (Branching Conyza) · C. sagittalis (Wingstem Camphorweed)
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- Cronquist, A. 1943. The separation of Erigeron from Conyza. Bull. Torrey Bot. Club 70: 629-632. 1943.
- Nesom, G. L. 1990c. Further definition of Conyza (Asteraceae: Astereae). Phytologia 68: 229-233.
- Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. Accessed January 11, 2012.
Accessed through GBIF Data Portal January 29, 2008:
- Harvard University Herbaria, Harvard University Herbaria
- Biodiversity Heritage Library NamebankID: 9404280
- Catalogue of Life Accepted Name Code: Ast-21090
- Global Biodiversity Information Facility Taxonkey: 15120374
- Globally Unique Identifier: urn:lsid:ipni.org:names:197196-1
- Zipcode Zoo Species Identifier: 3051131