Interesting Facts
Description
Genus Conyza
Annuals [perennials
], 10-120(-350+) cm. Stems usually erect
, branched mostly distally (spreading
and branched throughout in C.
ramosissima), glabrous
or hispid
, hispidulous
, strigillose
, or strigose
. Leaves basal and cauline (mostly cauline at flowering) ; alternate; petiolate
or sessile; blades
mostly lanceolate to oblanceolate
or linear
, margins
rarely lobed
, ultimate
toothed
or entire, faces
usually hispid, hispidulous, strigillose, or strigose (eglandular
). Heads radiate
or disciform
, usually in spreading to strict
, paniculiform
or corymbiform
arrays (borne ± singly in C. ramosissima). Involucres ± turbinate
, 2-5[-7+] mm diam. Phyllaries 20-40+ in 2-4 series, appressed
(usually reflexed
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
or smooth
, epaleate. Peripheral ("ray") florets pistillate
, fertile
: either 20-45+ in 1-2+ series, corollas white to purplish (filiform
with laminae
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
), tubes
shorter than narrowly funnelform
throats
, lobes
5, erect or spreading, deltate; style-branch appendages
deltate. Cypselae compressed
, oblong
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
, tawny
, 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.[1]
Taxonomy
)Notes
Name
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
Similar Species
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)
More Info
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Further Reading
- 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.
Notes
Contributors
- Brands, S.J. (comp.) 1989-present. The Taxonomicon. Universal Taxonomic Services, Zwaag, The Netherlands. Accessed January 11, 2012.
Data Sources
Accessed through GBIF Data Portal January 29, 2008:
- Harvard University Herbaria, Harvard University Herbaria
Identifiers
- 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
Footnotes
- John L. Strother "Conyza". in Flora of North America Vol. 20 Page 3, 9,11, 36, 257, 348, 349. Oxford University Press. Online at EFloras.org. [back]
