Difference between revisions of "Amphiachyris"

(de Candolle) Nuttall

Trans. Amer. Philos. Soc., n. s. 7: 313. 1840.

Common names: Broomweed
Etymology: Greek amphi -, around, and achyron, chaff or husks, alluding to ring of pappus elements
Basionym: Brachyris sect. Amphiachyris de Candolle Mém. Soc. Phys. Genève 7: 266. 1836
Treatment appears in FNA Volume 20. Treatment on page 87. Mentioned on page 9, 88, 89, 95.
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|name=Brachyris sect. Amphiachyris
 
|name=Brachyris sect. Amphiachyris
 
|authority=de Candolle
 
|authority=de Candolle
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|rank=section
 
|publication_title=Mém. Soc. Phys. Genève
 
|publication_title=Mém. Soc. Phys. Genève
 
|publication_place=7: 266. 1836
 
|publication_place=7: 266. 1836
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|family=Asteraceae
 
|family=Asteraceae
 
|illustrator=Barbara Alongi
 
|illustrator=Barbara Alongi
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|illustration copyright=Flora of North America Association
 
|distribution=c United States.
 
|distribution=c United States.
 
|reference=lane1979a
 
|reference=lane1979a
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|publication year=1840
 
|publication year=1840
 
|special status=
 
|special status=
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/f6b125a955440c0872999024f038d74684f65921/coarse_grained_fna_xml/V19-20-21/V20_167.xml
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|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-data-curation.git/src/bb6b7e3a7de7d3b7888a1ad48c7fd8f5c722d8d6/coarse_grained_fna_xml/V19-20-21/V20_167.xml
 
|tribe=Asteraceae tribe Astereae
 
|tribe=Asteraceae tribe Astereae
 
|genus=Amphiachyris
 
|genus=Amphiachyris

Revision as of 20:46, 27 May 2020

Annuals, 20–100(–200) cm (glabrous, with strong terpenoid smell when crushed; taprooted). Stems erect, usually branched distally (bases usually lignescent). Leaves cauline; alternate; sessile; blades (1- or 3-nerved) linear to lanceolate, margins entire, faces gland-dotted. Heads radiate, in paniculiform or corymbiform arrays. Involucres narrowly campanulate to turbinate, 2–4 mm diam. Phyllaries 12–15 in 1–2(–3) series, 1-nerved (nerves without green margins) ovate, unequal, proximal 2/3 indurate, margins hyaline, faces whitish resinous. Receptacles flat to slightly convex, smooth (glabrous or hairy with multicellular, 1-seriate hairs), epaleate. Ray florets 7–12, pistillate, fertile; corollas yellow, sometimes drying orange-tinged. Disc florets 10–21, functionally staminate; corollas yellow, tubes shorter than cylindric throats, lobes 5, erect, deltate; style-branch appendages fused (pappi of 5–8 white, basally connate, linear, spatulate-tipped scales in 1 series, ± equaling corollas). Cypselae (ray, purplish black) obovoid-turbinate, plump, 4–9-ribbed (apices attenuate to slightly clavate), faces densely long- or short-setulose (hairs appressed, white), mostly occurring in lines between ribs; pappi coroniform. x = 4, 5.

Distribution

c United States.

Discussion

Species 2 (2 in the flora).

Amphiachyris was recently treated within a more inclusive Gutierrezia (G. M. Diggs et al. 1999); apparently, it is more closely related to monotypic Thurovia than to Gutierrezia (Y. Suh and B. B. Simpson 1990). Amphiachyris is distinguished from Gutierrezia by a combination of glandular hairs only on the abaxial leaf faces, functionally staminate disc florets, disc pappi of basally connate, narrowly spatulate scales ± equaling corollas, and abaxial nerves of the phyllaries without green borders.

Key

1 Plants 20–40(–60) cm; heads in open paniculiform arrays; cypselae 4–6-ribbed, long-setulose; leaf blades 0.2–1(–2) mm wide; receptacles with hooked, swollen-based hairs Amphiachyris amoena
1 Plants 30–100(–200) cm; heads in crowded corymbiform arrays; cypselae 7–9-ribbed, short-setulose; leaf blades 0.5–6 mm wide; receptacles glabrous Amphiachyris dracunculoides