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-undefined" data-properties=""><b>Annuals </b>and perennials, mostly 20–120 cm. <b>Stems</b> often decumbent (rooting at proximal nodes), sparsely to densely branched. <b>Leaves</b> cauline; all or mostly opposite; petiolate; blades mostly 1-nerved, deltate to ovate, or elliptic to lanceolate, margins entire or toothed, faces glabrous or ± pilose, puberulent, or strigoso-hispid, sometimes gland-dotted. <b>Heads</b> discoid, in dense to open, cymiform to corymbiform arrays. <b>Involucres</b> campanulate, 3–6 mm. <b>Phyllaries</b> persistent, 30–40 in 2–3 series, usually 2-nerved, lanceolate, ± equal (often indurate, margins scarious). <b>Receptacles</b> conic, epaleate [paleate]. <b>Florets</b> 20–125; corollas white or bluish to lavender, throats ± campanulate (lengths 2 times diams.); styles: bases not enlarged, glabrous, branches ± linear to clavate (usually papillose and dilated distally). <b>Cypselae</b> prismatic, 4–5-ribbed, glabrous or sparsely strigoso-hispidulous; pappi persistent, of 5–6 aristate scales, or coroniform, or 0. <b>x</b> = 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://bitbucket.org/aafc-mbb/fna-data-curation/src/2e0870ddd59836b60bcf96646a41e87ea5a5943a/coarse_grained_fna_xml/V19-20-21/V21_1209.xml
|tribe=Asteraceae tribe Eupatorieae
|genus=Ageratum
}}<!--

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