View source for Ageratum

{{Treatment/ID
|accepted_name=Ageratum
|accepted_authority=Linnaeus
|publications={{Treatment/Publication
|title=Sp. Pl.
|place=2: 839. 1753
|year=1753
}}, {{Treatment/Publication
|title=Gen. Pl. ed.
|place=5, 363. 1754
|year=1754
}}
|basionyms=
|synonyms=
|hierarchy=Asteraceae;Asteraceae tribe Eupatorieae;Ageratum
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Eupatorieae]]</div><div class="higher-taxon"><small>genus</small>[[Ageratum]]</div></div>
|etymology=Greek a, not, and geras, old age, apparently alluding to long-lasting nature of flowers
|volume=Volume 21
|mention_page=page 460
|treatment_page=page 481
}}<!--

--><span class="statement" id="st-d0_s0" data-properties="whole-organism some measurement;whole-organism duration;whole-organism some measurement;whole-organism duration"><b>Annuals </b>and perennials, mostly 20–120 cm.</span> <span class="statement" id="st-d0_s1" data-properties="stem growth form or orientation;stem architecture"><b>Stems </b>often decumbent (rooting at proximal nodes), sparsely to densely branched.</span> <span class="statement" id="st-d0_s2" data-properties=""><b>Leaves </b>cauline;</span> <span class="statement" id="st-d0_s3" data-properties="">all or mostly opposite;</span> <span class="statement" id="st-d0_s4" data-properties="leaf position;leaf arrangement;leaf architecture">petiolate;</span> <span class="statement" id="st-d0_s5" data-properties="blade architecture;blade shape;blade shape;margin 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">blades mostly 1-nerved, deltate to ovate, or elliptic to lanceolate, margins entire or toothed, faces glabrous or ± pilose, puberulent, or strigoso-hispid, sometimes glanddotted.</span> <span class="statement" id="st-d0_s6" data-properties="head architecture or shape;head architecture"><b>Heads </b>discoid, in dense to open, cymiform to corymbiform arrays.</span> <span class="statement" id="st-d0_s7" data-properties="involucre shape;involucre some measurement"><b>Involucres </b>campanulate, 3–6 mm.</span> <span class="statement" id="st-d0_s8" data-properties="phyllary duration;phyllary quantity;phyllary architecture;phyllary shape;phyllary variability;series quantity"><b>Phyllaries </b>persistent, 30–40 in 2–3 series, usually 2-nerved, lanceolate, ± equal (often indurate, margins scarious).</span> <span class="statement" id="st-d0_s9" data-properties="receptacle shape;receptacle architecture"><b>Receptacles </b>conic, epaleate [paleate].</span> <span class="statement" id="st-d0_s10" data-properties="floret quantity"><b>Florets </b>20–125;</span> <span class="statement" id="st-d0_s11" data-properties="corolla coloration;throat shape">corollas white or bluish to lavender, throats ± campanulate (lengths 2 times diams.);</span> <span class="statement" id="st-d0_s12" data-properties="base size;base pubescence;branch shape">styles: bases not enlarged, glabrous, branches ± linear to clavate (usually papillose and dilated distally).</span> <span class="statement" id="st-d0_s13" data-properties="cypsela shape;cypsela architecture or shape;cypsela pubescence;cypsela pubescence"><b>Cypselae </b>prismatic, 4–5-ribbed, glabrous or sparsely strigoso-hispidulous;</span> <span class="statement" id="st-d0_s14" data-properties="scale quantity;scale shape">pappi persistent, of 5–6 aristate scales, or coroniform, or 0.</span> <span class="statement" id="st-d0_s15" data-properties="pappus duration;pappus shape;pappus presence;x chromosome quantity">x = 10.</span><!--

-->{{Treatment/Body
|distribution=United States;Mexico;Central America;2 species widespread as adventives
|discussion=<p>Species ca. 40 (4 in the flora).</p>
|tables=
|references={{Treatment/Reference
|id=johnson1971a
|text=Johnson, M. F. 1971. A monograph of the genus Ageratum L. (Compositae–Eupatorieae). Ann. Missouri Bot. Gard. 58: 6–88.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Plants colonial; stems and leaves glabrous or glabrate
|[[Ageratum maritimum|Ageratum maritimum]]
|-id=key-0-1
|1
|Plants not colonial; stems and leaves hairy
|[[#key-0-2| > 2]]
|-id=key-0-2
|2
|Stems puberulent to minutely strigoso-hispid; cypselae glabrous
|[[Ageratum corymbosum|Ageratum corymbosum]]
|-id=key-0-2
|2
|Stems sparsely to densely pilose (usually in combination with other forms of vestiture); cypselae sparsely strigoso-hispidulous.
|[[#key-0-3| > 3]]
|-id=key-0-3
|3
|Peduncles minutely puberulent and sparsely to densely pilose, eglandular; phyllaries oblong-lanceolate, abruptly tapering to subulate tips 0.5–1 mm, glabrous or sparsely pilose, margins often ciliate, abaxial faces eglandular
|[[Ageratum conyzoides|Ageratum conyzoides]]
|-id=key-0-3
|3
|Peduncles mixed pilose, stipitate-glandular, and viscid-puberulent; phyllaries narrowly lanceolate, gradually tapering to indurate-subulate tips 0.8–2 mm, margins not ciliate or inconspicuously ciliate, abaxial faces stipitate-glandular and sparsely to densely pilose
|[[Ageratum houstonianum|Ageratum houstonianum]]
|}
</div></div><!--

-->{{#Taxon:
name=Ageratum
|author=Guy L. Nesom
|authority=Linnaeus
|rank=genus
|parent rank=tribe
|synonyms=
|basionyms=
|family=Asteraceae
|distribution=United States;Mexico;Central America;2 species widespread as adventives
|reference=johnson1971a
|publication title=Sp. Pl.;Gen. Pl. ed.
|publication year=1753;1754
|special status=
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-fine-grained-xml.git/src/84153f6d59a0a91d69695978a64cee7560374f8e/V19-20-21/V21_1209.xml
|tribe=Asteraceae tribe Eupatorieae
|genus=Ageratum
|base pubescence=glabrous
|base size=not enlarged
|blade architecture=1-nerved
|blade shape=deltate;ovate or elliptic
|branch shape=less linear;clavate
|corolla coloration=bluish;lavender
|cypsela architecture or shape=4-5-ribbed
|cypsela pubescence=strigoso-hispidulous;glabrous
|cypsela shape=prismatic
|face pubescence=strigoso-hispid;puberulent;pilose;glabrous;strigoso-hispid;puberulent;pilose;glabrous;strigoso-hispid;puberulent;pilose;glabrous
|floret quantity=20;125
|head architecture=cymiform;corymbiform
|head architecture or shape=discoid
|involucre shape=campanulate
|involucre some measurement=3mm;6mm
|leaf architecture=petiolate
|leaf arrangement=opposite
|leaf position=cauline
|margin shape=toothed;entire
|pappus duration=persistent
|pappus presence=absent
|pappus shape=coroniform
|phyllary architecture=2-nerved
|phyllary duration=persistent
|phyllary quantity=30;40
|phyllary shape=lanceolate
|phyllary variability=equal
|receptacle architecture=epaleate
|receptacle shape=conic
|scale quantity=5;6
|scale shape=aristate
|series quantity=2;3
|stem architecture=branched
|stem growth form or orientation=decumbent
|throat shape=campanulate
|whole-organism duration=perennial;annual
|whole-organism some measurement=20cm;120cm
|x chromosome quantity=10
}}<!--

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