View source for Isocoma

{{Treatment/ID
|accepted_name=Isocoma
|accepted_authority=Nuttall
|publications={{Treatment/Publication
|title=Trans. Amer. Philos. Soc., n. s.
|place=7: 320. 1840
|year=1840
}}
|common_names=Jimmyweed;goldenweed
|basionyms=
|synonyms={{Treatment/ID/Synonym
|name=Haplopappus sect. Isocoma
|authority=(Nuttall) H. M. Hall
|rank=section
}}
|hierarchy=Asteraceae;Asteraceae tribe Astereae;Isocoma
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Astereae]]</div><div class="higher-taxon"><small>genus</small>[[Isocoma]]</div></div>
|etymology=Greek isos, equal, and kome, hair of the head; “so called from its equal flowers” (protologue)
|volume=Volume 20
|mention_page=page 7, 13, 89, 438, 445
|treatment_page=page 439
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="whole-organism atypical some measurement;whole-organism atypical some measurement;whole-organism some measurement;whole-organism duration;whole_organism atypical some measurement;whole_organism atypical some measurement;whole_organism some measurement;whole_organism growth form"><b>Perennials </b>or subshrubs, (4–) 20–120 (–150) cm (bases often woody).</span> <span class="statement" id="st-d0_s1" data-properties="stem orientation;stem architecture;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem pubescence;stem coloration;stem pubescence;stem architecture;stem coating"><b>Stems </b>usually strictly erect, few-branched, glabrous or hispidulous, villous, or tomentose, usually gland-dotted (sessile or slightly sunken in pits), sometimes stipitate-glandular, rarely eglandular, often resinous.</span> <span class="statement" id="st-d0_s2" data-properties="leaf position"><b>Leaves </b>mostly cauline;</span> <span class="statement" id="st-d0_s3" data-properties="">alternate;</span> <span class="statement" id="st-d0_s4" data-properties="leaf arrangement;leaf architecture">sessile;</span> <span class="statement" id="st-d0_s5" data-properties="blade architecture;blade shape;margin shape;face pubescence;face pubescence;face pubescence;face pubescence;face pubescence;face pubescence;face pubescence;face pubescence;face pubescence;face pubescence;face pubescence;face pubescence;face coloration">blades 1-nerved, linear to oblanceolate or obovate, margins entire or toothed to pinnatifid (teeth or lobes often spinulose-tipped), faces glabrous or hispidulous, villous, or tomentose, usually gland-dotted (in pits).</span> <span class="statement" id="st-d0_s6" data-properties="head architecture or shape;head arrangement;borne architecture or arrangement;borne arrangement;terminal array architecture"><b>Heads </b>discoid, (sessile or subsessile) in compact clusters borne in terminal corymbiform arrays, rarely borne singly.</span> <span class="statement" id="st-d0_s7" data-properties="involucre shape;involucre length;involucre width"><b>Involucres </b>obconic to turbinate or campanulate, (3–9.5 ×) 2–8 mm.</span> <span class="statement" id="st-d0_s8" data-properties="phyllarie quantity;phyllarie architecture;phyllarie shape;phyllarie size;series atypical quantity;series quantity;margin texture;apex coloration;face pubescence;face pubescence;face coloration"><b>Phyllaries </b>15–30 in (3–) 4–6 series, 1-nerved (midnerves usually barely evident; flat to convex), oblong to elliptic-lanceolate, unequal, margins narrowly scarious, apices sometimes green, faces glabrous or tomentose, sometimes gland-dotted, sometimes with resin pockets.</span> <span class="statement" id="st-d0_s9" data-properties="receptacle prominence or shape;receptacle relief;receptacle architecture"><b>Receptacles </b>flat, pitted, epaleate.</span> <span class="statement" id="st-d0_s10" data-properties="disc-floret quantity;disc-floret reproduction;disc-floret reproduction"><b>Disc-</b>florets 8–34, bisexual, fertile;</span> <span class="statement" id="st-d0_s11" data-properties="corolla coloration;vein coloration;tube length or size;throat size;throat shape;lobe quantity;lobe orientation;lobe shape">corollas yellow with dark orange-resinous veins, tubes (with at least a few glandular-hairs) longer than abruptly ampliate, goblet-shaped throats (tube elevating corollas above involucres at flowering), lobes 5, erect, deltate (elongating at maturity, unequal, outer prominently bent or leaning outward, abruptly enlarged);</span> <span class="statement" id="st-d0_s12" data-properties="style-branch appendage shape">style-branch appendages narrowly triangular.</span> <span class="statement" id="st-d0_s13" data-properties="cypsela shape;cypsela shape;cypsela shape;cypsela architecture or shape;face pubescence"><b>Cypselae </b>(brownish) obpyramidal, terete or subterete, 5–11-ribbed (sometimes thick and resinous), faces sericeous;</span> <span class="statement" id="st-d0_s14" data-properties="bristle quantity;bristle width;bristle size;bristle architecture;bristle shape;series atypical quantity;series quantity">pappi persistent, of 40–50 unevenly thick, unequal, barbellate, apically attenuate bristles in 2 (–3) series.</span> <span class="statement" id="st-d0_s15" data-properties="pappus duration;x chromosome quantity">x = 6.</span><!--

-->{{Treatment/Body
|distribution=sw United States;Mexico
|discussion=<p>Species 16 (10 in the flora).</p><!--
--><p>Isocoma is recognized by its subshrubby habit, gland-dotted (sometimes stipitate-glandular), often resinous leaves, compactly clustered discoid heads in terminal, corymbiform arrays, goblet-shaped disc corollas, and base chromosome number of x = 6. H. M. Hall (1928) regarded the group as a section of Haplopappus, as did A. Cronquist (1994). Naturally occurring hybrids in south-central Mexico have been observed between Isocoma veneta (Kunth) Greene and Xanthocephalum humile (Kunth) Bentham (R. L. Hartman and M. A. Lane 1991).</p>
|tables=
|references={{Treatment/Reference
|id=nesom1991b
|text=Nesom, G. L. 1991c. Taxonomy of Isocoma (Asteraceae: Astereae). Phytologia 70: 69–114.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Phyllary apices with strongly developed resin pockets
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Phyllary apices gland-dotted (rarely so in I. coronopifolia), lacking resin pockets or pockets small, weakly developed
|[[#key-0-3| > 3]]
|-id=key-0-2
|2
|Teeth or lobes of leaf margins apically rounded-obtuse; florets 8–27; phyllary apices not spinulose-aristate, or if spinulose-aristate, then florets 20–27
|[[Isocoma acradenia|Isocoma acradenia]]
|-id=key-0-2
|2
|Teeth or lobes of leaf margins apically spinulose; florets 10–13; phyllary apices spinulose-aristate
|[[Isocoma arguta|Isocoma arguta]]
|-id=key-0-3
|3
|Leaves pinnatifid
|[[#key-0-4| > 4]]
|-id=key-0-3
|3
|Leaves entire or shallowly toothed to lobed, not pinnatifid
|[[#key-0-6| > 6]]
|-id=key-0-4
|4
|Herbage minutely hispidulous or sparsely puberulous (at least distal stems)
|[[Isocoma tenuisecta|Isocoma tenuisecta]]
|-id=key-0-4
|4
|Herbage glabrous
|[[#key-0-5| > 5]]
|-id=key-0-5
|5
|Involucres 5–7.5 mm wide; florets 18–25
|[[Isocoma azteca|Isocoma azteca]]
|-id=key-0-5
|5
|Involucres 2.5–4 mm wide; florets 12–15
|[[Isocoma coronopifolia|Isocoma coronopifolia]]
|-id=key-0-6
|6
|Phyllary apices distinctly aristate-spinulose; florets 10–13; California
|[[Isocoma arguta|Isocoma arguta]]
|-id=key-0-6
|6
|Phyllary apices not aristate-spinulose; florets 8–34; California and eastward
|[[#key-0-7| > 7]]
|-id=key-0-7
|7
|Involucres 3.2–7 × 2.5–4 mm; florets 8–17(–21)
|[[#key-0-8| > 8]]
|-id=key-0-7
|7
|Involucres 5–9 × 4.5–8 mm; florets (15–)18–34
|[[#key-0-9| > 9]]
|-id=key-0-8
|8
|Leaves never stipitate-glandular but almost always resinous, glabrous; involucres 5–7 mm
|[[Isocoma coronopifolia|Isocoma coronopifolia]]
|-id=key-0-8
|8
|Leaves sometimes stipitate-glandular, never resinous, margins hispidulous, sometimes also on faces; involucres 3.2–5.5 mm
|[[Isocoma pluriflora|Isocoma pluriflora]]
|-id=key-0-9
|9
|Leaves 5–10(–18) mm; corollas 4–5 mm
|[[Isocoma humilis|Isocoma humilis]]
|-id=key-0-9
|9
|Leaves (in I. menziesii 5–)13–50 mm; corollas 5–7.5 mm
|[[#key-0-10| > 10]]
|-id=key-0-10
|10
|Leaf margins entire or toothed to lobed; California
|[[Isocoma menziesii|Isocoma menziesii]]
|-id=key-0-10
|10
|Leaf margins entire; e of California
|[[#key-0-11| > 11]]
|-id=key-0-11
|11
|Involucres (5.5–)6–9.5 × 5–7.5 mm; phyllary apices yellowish to greenish yellow, sparsely or not at all gland-dotted; florets 19–25, corollas 5–6.5 mm; cypsela ribs forming hornlike extensions; Arizona, Colorado, New Mexico, Utah
|[[Isocoma rusbyi|Isocoma rusbyi]]
|-id=key-0-11
|11
|Involucres (5.5–)6.5–8 × 4.5–5.5(–7) mm; phyllary apices usually green, usually densely gland-dotted; florets (18–)22–34, corollas 5.8–7.5 mm; cypsela ribs not forming hornlike extensions; Texas
|[[Isocoma drummondii|Isocoma drummondii]]
|}
</div></div><!--

-->{{#Taxon:
name=Isocoma
|author=Guy L. Nesom
|authority=Nuttall
|rank=genus
|parent rank=tribe
|synonyms=Haplopappus sect. Isocoma
|basionyms=
|family=Asteraceae
|illustrator=Barbara Alongi
|illustration copyright=Flora of North America Association
|distribution=sw United States;Mexico
|reference=nesom1991b
|publication title=Trans. Amer. Philos. Soc., n. s.
|publication year=1840
|special status=
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-fine-grained-xml.git/src/84153f6d59a0a91d69695978a64cee7560374f8e/V19-20-21/V20_1005.xml
|tribe=Asteraceae tribe Astereae
|genus=Isocoma
|apex coloration=green
|blade architecture=1-nerved
|blade shape=linear;oblanceolate or obovate
|borne architecture or arrangement=compact
|borne arrangement=cluster
|bristle architecture=barbellate
|bristle quantity=40;50
|bristle shape=attenuate
|bristle size=unequal
|bristle width=thick
|corolla coloration=yellow
|cypsela architecture or shape=5-11-ribbed
|cypsela shape=subterete;terete;obpyramidal
|disc-floret quantity=8;34
|disc-floret reproduction=fertile;bisexual
|face coloration=gland-dotted;gland-dotted
|face pubescence=sericeous;tomentose;glabrous;tomentose;villous;hispidulous;glabrous;tomentose;villous;hispidulous;glabrous;tomentose;villous;hispidulous;glabrous
|head architecture or shape=discoid
|head arrangement=singly
|involucre length=[3mm;9.5mm
|involucre shape=obconic;turbinate or campanulate
|involucre width=]2mm;8mm
|leaf architecture=sessile
|leaf arrangement=alternate
|leaf position=cauline
|lobe orientation=erect
|lobe quantity=5
|lobe shape=deltate
|margin shape=toothed;pinnatifid
|margin texture=scarious
|pappus duration=persistent
|phyllarie architecture=1-nerved
|phyllarie quantity=15;30
|phyllarie shape=oblong;elliptic-lanceolate
|phyllarie size=unequal
|receptacle architecture=epaleate
|receptacle prominence or shape=flat
|receptacle relief=pitted
|series atypical quantity=2;3
|series quantity=2;4;6
|stem architecture=eglandular;few-branched
|stem coating=resinous
|stem coloration=gland-dotted
|stem orientation=erect
|stem pubescence=stipitate-glandular;tomentose;villous;hispidulous;glabrous;tomentose;villous;hispidulous;glabrous;tomentose;villous;hispidulous;glabrous
|style-branch appendage shape=triangular
|terminal array architecture=corymbiform
|throat shape=goblet--shaped
|throat size=ampliate
|tube length or size=longer
|vein coloration=dark orange-resinous
|whole-organism atypical some measurement=120cm;150cm
|whole-organism duration=perennial
|whole-organism some measurement=20cm;120cm
|whole_organism atypical some measurement=120cm;150cm
|whole_organism growth form=subshrub
|whole_organism some measurement=20cm;120cm
|x chromosome quantity=6
}}<!--

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