View source for Gamochaeta

{{Treatment/ID
|accepted_name=Gamochaeta
|accepted_authority=Weddell
|publications={{Treatment/Publication
|title=Chlor. Andina
|place=1: 151. 1856
|year=1856
}}
|basionyms=
|synonyms={{Treatment/ID/Synonym
|name=Gnaphalium sect. Gamochaeta
|authority=(Weddell) O. Hoffmann
|rank=section
}} {{Treatment/ID/Synonym
|name=Gnaphalium subg. Gamochaeta
|authority=(Weddell) Grenier
|rank=subgenus
}}
|hierarchy=Asteraceae;Asteraceae tribe Gnaphalieae;Gamochaeta
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Gnaphalieae]]</div><div class="higher-taxon"><small>genus</small>[[Gamochaeta]]</div></div>
|etymology=Greek gamos, union, and chaete, loose and flowing hair, alluding to basally connate pappus bristles
|volume=Volume 19
|mention_page=page 60, 387, 429
|treatment_page=page 431
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="whole-organism duration"><b>Annuals,</b> biennials, or perennials, (1–) 5–65 cm;</span> <span class="statement" id="st-d0_s1" data-properties="whole-organism atypical some measurement;whole-organism some measurement;whole-organism architecture;whole-organism architecture;whole-organism duration;whole-organism atypical some measurement;whole-organism some measurement;whole-organism architecture;whole-organism architecture;whole-organism duration">taprooted or fibrous-rooted [subrhizomatous].</span> <span class="statement" id="st-d0_s2" data-properties="stem quantity;stem orientation;stem orientation"><b>Stems </b>1+, usually erect, sometimes decumbent-ascending.</span> <span class="statement" id="st-d0_s3" data-properties=""><b>Leaves </b>basal and cauline;</span> <span class="statement" id="st-d0_s4" data-properties="">alternate;</span> <span class="statement" id="st-d0_s5" data-properties="leaf position;leaf position;leaf arrangement;leaf architecture">sessile;</span> <span class="statement" id="st-d0_s6" data-properties="blade shape;base shape;margin architecture or shape;margin shape;abaxial face coloration;abaxial face coloration;abaxial face pubescence;abaxial face pubescence;adaxial face coloration;adaxial face pubescence;adaxial face pubescence;adaxial face coloration;adaxial face pubescence;adaxial face pubescence;adaxial face pubescence;adaxial face pubescence;adaxial face pubescence">blades mostly linear to oblanceolate or spatulate, bases cuneate to ± cordate, margins entire, sometimes sinuate, abaxial faces mostly white or gray and tomentose or pannose-tomentose, adaxial green and glabrescent or glabrous, or grayish and arachnose, loosely tomentose, or subpannose.</span> <span class="statement" id="st-d0_s7" data-properties="head architecture or shape;array architecture;array architecture;array architecture;array architecture"><b>Heads </b>disciform, usually in glomerules borne in continuous or interrupted, usually spiciform, sometimes paniculiform, arrays (reduced to terminal glomerules in depauperate individuals).</span> <span class="statement" id="st-d0_s8" data-properties="involucre shape;involucre some measurement"><b>Involucres </b>narrowly to broadly campanulate, 2.5–5 mm.</span> <span class="statement" id="st-d0_s9" data-properties="phyllary size;phyllary coloration;phyllary coloration;phyllary coloration;phyllary reflectance;phyllary texture;phyllary architecture;series quantity"><b>Phyllaries </b>in 3–7 series, unequal, mostly brownish to stramineous, sometimes purplish, hyaline, often shiny, distally chartaceous to scarious, eglandular.</span> <span class="statement" id="st-d0_s10" data-properties="receptacle prominence or shape;receptacle pubescence;receptacle architecture"><b>Receptacles </b>flat (concave in fruit), glabrous, epaleate.</span> <span class="statement" id="st-d0_s11" data-properties="floret architecture;floret quantity;floret quantity;floret reproduction"><b>Pistillate </b>florets 50–130, more numerous than bisexual florets;</span> <span class="statement" id="st-d0_s12" data-properties="corolla coloration;corolla coloration">corollas all yellow or purplish-tipped.</span> <span class="statement" id="st-d0_s13" data-properties="floret reproduction;floret quantity"><b>Bisexual </b>florets 2–7;</span> <span class="statement" id="st-d0_s14" data-properties="corolla coloration;corolla coloration">corollas all yellow or distally purplish.</span> <span class="statement" id="st-d0_s15" data-properties="cypsela shape;cypsela shape;hair shape"><b>Cypselae </b>oblong, slightly flattened, faces with papilliform hairs (myxogenic, their lengths about equaling diams.);</span> <span class="statement" id="st-d0_s16" data-properties="bristle quantity;bristle architecture;series quantity">pappi readily falling, of 12–28 barbellulate bristles in 1 series (basally connate in smooth rings, falling as units).</span> <span class="statement" id="st-d0_s17" data-properties="pappus life cycle;x chromosome quantity">x = 7.</span><!--

-->{{Treatment/Body
|distribution=North America;Mexico;West Indies;Central America;South America;some species adventive and naturalized in Europe;Asia;Australia;and elsewhere
|discussion=<p>Species ca. 50 (12 in the flora).</p><!--
--><p>Gamochaeta comprises about 50 species (A. L. Cabrera 1961; S. E. Freire and L. Iharlegui 1997) or about 80 species (Cabrera 1977+, part 10), all native to the Americas. Most are known only from South America; some apparently are native to Mexico and the flora area (G. L. Nesom 2004b). Some species are strongly weedy and have extended non-native ranges. Because of inconsistencies in the identification of those species, it has been difficult to evaluate the overall distributions of the widespread species.</p><!--
--><p>The distinctiveness of Gamochaeta was emphasized by A. L. Cabrera (1961, and in later floristic treatments of South American species) and by other botanists who have treated it as a separate genus in the last decade. The genus is distinguished by its combination of relatively small heads in spiciform arrays, concave post-fruiting receptacles, truncate collecting appendages of style branches in bisexual florets, relatively small cypselae with minute, mucilage-producing papilliform hairs on the faces, and pappus bristles basally connate in smooth rings and released as single units. It seems likely that most species are primarily autogamous, in view of the tiny, non-showy heads that barely open through flowering. The consistency of vegetative and floral features in some of the species supports this hypothesis.</p><!--
--><p>In the flora area, some species have commonly been treated as variants within Gamochaeta purpurea; distinctions are evident in the field, where it is common to find as many as five species growing in proximity without intergradation. Species of Gamochaeta are distinguished by differences primarily in root form, leaf shape, nature and distribution of indument, and phyllary morphology. Chromosome counts have been reported for some species; because of the unreliability of identifications, vouchers for those counts should be restudied.</p>
|tables=
|references={{Treatment/Reference
|id=freire1997a
|text=Freire, S. E. and L. Iharlegui. 1997. Sinopsis preliminar del género Gamochaeta (Asteraceae, Gnaphalieae). Bol. Soc. Argent. Bot. 33: 23–35.
}}{{Treatment/Reference
|id=nesom1990a
|text=Nesom, G. L. 1990f. The taxonomic status of Gamochaeta (Asteraceae: Inuleae) and the species of the United States. Phytologia 68: 186–198.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Leaves bicolor (abaxial faces closely white-pannose to pannose-tomentose, indument obscuring epidermis, adaxial faces glabrous or glabrate to sparsely arachnose)
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Leaves concolor or weakly bicolor (abaxial and adaxial faces ± equally greenish to gray-greenish, indument usually loosely tomentose or arachnose, sometimes subpannose, adaxial sometimes glabrescent in G. stagnalis)
|[[#key-0-7| > 7]]
|-id=key-0-2
|2
|Basal and proximal cauline leaves usually withering before flowering (clusters of smaller leaves usually present in cauline axils); stems erect or ascending; plants (30–)50–85 cm; apices of inner phyllaries acute-acuminate; flowering mostly Jul–Aug
|[[Gamochaeta simplicicaulis|Gamochaeta simplicicaulis]]
|-id=key-0-2
|2
|Basal and proximal cauline leaves present or not at flowering; stems erect to decumbent-ascending; plants mostly 10–50 cm; apices of inner phyllaries acute to obtuse, rounded, or blunt; flowering mostly Apr–Jun(–Jul in G. calviceps)
|[[#key-0-3| > 3]]
|-id=key-0-3
|3
|Adaxial leaf faces glabrous or glabrate; involucres (± purplish) 2.5–3 mm, bases glabrous; outer phyllaries elliptic-obovate to broadly ovate-elliptic, apices rounded to obtuse; bisexual florets 2–3
|[[Gamochaeta coarctata|Gamochaeta coarctata]]
|-id=key-0-3
|3
|Adaxial leaf faces sparsely arachnose (hairs persistent, evident at 10×); involucres (sometimes purplish) 3–4.5(–5) mm, bases (imbedded in tomentum) often sparsely arachnose on proximal 1/5–1/2; outer phyllaries ovate, ovate-triangular, or ovate-lanceolate, apices acute to acuminate; bisexual florets 2–6
|[[#key-0-4| > 4]]
|-id=key-0-4
|4
|Stems not pannose (induments whitish, like closely appressed, polished cloth, hairs usually not individually evident); involucres 3–3.5(–4) mm; apices of inner phyllaries acute to acute-acuminate; bisexual florets 2–4 (cypselae purple)
|[[Gamochaeta chionesthes|Gamochaeta chionesthes]]
|-id=key-0-4
|4
|Stems usually ± pannose or pannose-tomentose (hairs individually evident, longitudinally arranged); involucres 3–4.5 mm; apices of inner phyllaries acute, obtuse, or truncate-rounded, sometimes apiculate; bisexual florets 3–6 (cypselae tan to brownish)
|[[#key-0-5| > 5]]
|-id=key-0-5
|5
|Blades of cauline leaves oblanceolate to spatulate (basal cells of hairs on adaxial faces persistent, expanded, glassy); involucres 4–4.5 mm; laminae of inner phyllaries triangular, apices acute (not apiculate); bisexual florets 3–4; plants fibrous-rooted or taprooted
|[[Gamochaeta purpurea|Gamochaeta purpurea]]
|-id=key-0-5
|5
|Blades of cauline leaves oblanceolate to oblanceolate-oblong or oblanceolate-obovate; involucres 4.5–5 or 3–3.5 mm; laminae of inner phyllaries elliptic-oblong to oblong, apices truncate-rounded or obtuse and apiculate; bisexual florets (3–)4–6; plants usually fibrous-rooted, rarely taprooted
|[[#key-0-6| > 6]]
|-id=key-0-6
|6
|Arrays of heads uninterrupted (1–5 cm in early flowering) to strongly interrupted, mostly 5–18 cm × 10–12 mm (pressed); involucres 3–3.5 mm; outer phyllaries (tawny-transparent, never dark brown) ovate to ovate-lanceolate; cypselae 0.5–0.6 mm
|[[Gamochaeta argyrinea|Gamochaeta argyrinea]]
|-id=key-0-6
|6
|Arrays of heads usually continuous, rarely interrupted (then proximally), mostly 1–6(–8) cm × 12–18 mm (pressed); involucres 4.5–5 mm; outer phyllaries (and, often, laminae of inner, dark or greenish brown) broadly ovate-triangular (mid phyllaries ± keeled near apices); cypselae 0.7–0.8 mm
|[[Gamochaeta ustulata|Gamochaeta ustulata]]
|-id=key-0-7
|7
|Leaf blades linear to narrowly oblanceolate (often folded along midveins, distally becoming arcuate, ± patent bracts surpassing the heads; basal cells of hairs on adaxial faces expanded, glassy); apices of outer phyllaries (brown) acute-acuminate (usually involute and spreading or recurving); Texas, near Mexican border
|[[Gamochaeta sphacelata|Gamochaeta sphacelata]]
|-id=key-0-7
|7
|Leaf blades linear or linear-oblanceolate to spatulate, narrowly lanceolate, oblong-oblanceolate, oblanceolate-obovate, or oblanceolate (folded or not; if distal leaves or bracts surpassing heads, not arcuate and ± patent); apices of outer phyllaries (sometimes brownish) sometimes acute to acute-acuminate or attenuate-apiculate (not involute, except in G. calviceps); mostly (not always) se United States.
|[[#key-0-8| > 8]]
|-id=key-0-8
|8
|Blades of basal and proximal cauline leaves 4–16 mm wide (bracts among heads spatulate to oblanceolate, at least the proximal surpassing the glomerules of heads)
|[[Gamochaeta pensylvanica|Gamochaeta pensylvanica]]
|-id=key-0-8
|8
|Blades of basal and proximal cauline leaves 2–6(–10) mm wide (mid and distal cauline becoming oblanceolate to linear, bracts among heads linear, oblanceolate, or oblong-oblanceolate, surpassing glomerules or not)
|[[#key-0-9| > 9]]
|-id=key-0-9
|9
|Blades of mid and distal cauline leaves oblanceolate (bases subclasping; bracts among heads mostly shorter than glomerules); involucres (not purplish) 3.5–4 mm; phyl- laries in 4–5 series
|[[Gamochaeta stachydifolia|Gamochaeta stachydifolia]]
|-id=key-0-9
|9
|Blades of mid and distal cauline leaves oblong-oblanceolate or oblanceolate to spatulate, narrowly lanceolate, linear-oblanceolate, or linear (bases not subclasping; bracts among heads shorter or longer than glomerules); involucres (sometimes purplish) 2.5–3.5 mm; phyllaries in 5–7 or 3–4(–5) series
|[[#key-0-10| > 10]]
|-id=key-0-10
|10
|Involucres (not purplish) 3–3.5 mm, bases sparsely arachnose or glabrous; arrays of heads interrupted (at least distally, main axes visible between heads); phyllaries in 5–7 series, outer ovate-triangular, lengths 1/3–1/2 inner, apices acute-acuminate; flowering May–Jul
|[[Gamochaeta calviceps|Gamochaeta calviceps]]
|-id=key-0-10
|10
|Involucres (usually purplish, at stereome-lamina junctions of phyllaries) 2.5–3 mm, bases sparsely arachnose; arrays of heads initially capitate clusters or cylindric and uninterrupted (at least distally, main axes obscured by heads); phyllaries in 3–4(–5) series, outer ovate-lanceolate, lengths 1/2–2/3 inner, apices narrowly to broadly acute; flowering (Feb–)Mar–May (later with moisture)
|[[#key-0-11| > 11]]
|-id=key-0-11
|11
|Cauline leaves and bracts among heads narrowly lanceolate, linear-oblanceolate, or linear; arrays of heads initially uninterrupted cylindro- spiciform (becoming glomerulate-interrupted in late flowering)
|[[Gamochaeta antillana|Gamochaeta antillana]]
|-id=key-0-11
|11
|Cauline leaves and bracts among heads mostly oblanceolate to oblong-oblanceolate (± uniform in size and shape); arrays of heads capitate clusters or interrupted spiciform arrays (from early through late flowering)
|[[Gamochaeta stagnalis|Gamochaeta stagnalis]]
|}
</div></div><!--

-->{{#Taxon:
name=Gamochaeta
|author=Guy L. Nesom
|authority=Weddell
|rank=genus
|parent rank=tribe
|synonyms=Gnaphalium sect. Gamochaeta;Gnaphalium subg. Gamochaeta
|basionyms=
|family=Asteraceae
|illustrator=Barbara Alongi
|illustration copyright=Flora of North America Association
|distribution=North America;Mexico;West Indies;Central America;South America;some species adventive and naturalized in Europe;Asia;Australia;and elsewhere
|reference=freire1997a;nesom1990a
|publication title=Chlor. Andina
|publication year=1856
|special status=
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-fine-grained-xml.git/src/84153f6d59a0a91d69695978a64cee7560374f8e/V19-20-21/V19_711.xml
|tribe=Asteraceae tribe Gnaphalieae
|genus=Gamochaeta
|abaxial face coloration=gray;white
|abaxial face pubescence=pannose-tomentose;tomentose
|adaxial face coloration=grayish;green
|adaxial face pubescence=subpannose;tomentose;subpannose;tomentose;arachnose;glabrous;glabrescent
|array architecture=paniculiform;spiciform;interrupted;continuous
|base shape=cuneate;more or less cordate
|blade shape=mostly linear;oblanceolate or spatulate
|bristle architecture=barbellulate
|bristle quantity=12;28
|corolla coloration=purplish;yellow;purplish-tipped;yellow
|cypsela shape=flattened;oblong
|floret architecture=pistillate
|floret quantity=2;7
|floret reproduction=bisexual;bisexual
|hair shape=papilliform
|head architecture or shape=disciform
|involucre shape=campanulate
|involucre some measurement=2.5mm;5mm
|leaf architecture=sessile
|leaf arrangement=alternate
|leaf position=cauline;basal
|margin architecture or shape=entire
|margin shape=sinuate
|pappus life cycle=falling
|phyllary architecture=eglandular
|phyllary coloration=hyaline;purplish;mostly brownish;stramineous
|phyllary reflectance=shiny
|phyllary size=unequal
|phyllary texture=distally chartaceous;scarious
|receptacle architecture=epaleate
|receptacle prominence or shape=flat
|receptacle pubescence=glabrous
|series quantity=1;3;7
|stem orientation=decumbent-ascending;erect
|whole-organism architecture=fibrous-rooted;taprooted;fibrous-rooted;taprooted
|whole-organism atypical some measurement=1cm;5cm
|whole-organism duration=perennial;biennial;annual
|whole-organism some measurement=5cm;65cm
|x chromosome quantity=7
}}<!--

-->[[Category:Treatment]][[Category:Asteraceae tribe Gnaphalieae]]