View source for Iva

{{Treatment/ID
|accepted_name=Iva
|accepted_authority=Linnaeus
|publications={{Treatment/Publication
|title=Sp. Pl.
|place=2: 988. 1753
|year=1753
}}, {{Treatment/Publication
|title=Gen. Pl. ed.
|place=5, 426. 1754
|year=1754
}}
|common_names=Marsh elder
|basionyms=
|synonyms=
|hierarchy=Asteraceae;Asteraceae tribe Heliantheae;Asteraceae (tribe Heliantheae) subtribe Ambrosiinae;Iva
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Heliantheae]]</div><div class="higher-taxon"><small>subtribe</small>[[Asteraceae (tribe Heliantheae) subtribe Ambrosiinae]]</div><div class="higher-taxon"><small>genus</small>[[Iva]]</div></div>
|etymology=Etymology uncertain; perhaps for Ajuga iva, a mint with similar odor
|volume=Volume 21
|mention_page=page 9
|treatment_page=page 25
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Annuals,</b> perennials, subshrubs, or shrubs, 10–350 cm. <b>Stems</b> usually erect, sometimes decumbent to sprawling, often freely branched. <b>Leaves</b> cauline; mostly opposite (distal sometimes alternate); petiolate or sessile; blades (1- or 3-nerved) deltate, elliptic, filiform, lanceolate, linear, obovate, ovate, spatulate, or trullate, margins entire or toothed, faces glabrous or ± scabrellous, often gland-dotted. <b>Heads</b> discoid or ± disciform, in (± bracteate) racemiform or spiciform arrays (heads 1–2 in axil of each bract, bracts sometimes leaflike). <b>Involucres</b> ± hemispheric or turbinate to campanulate or urceolate, 2–10+ mm diam. <b>Phyllaries</b> persistent, 3–15+ in 1–3+ series, distinct or ± connate, all ± herbaceous or inner scarious to membranous. <b>Receptacles</b> flat or convex to hemispheric; paleae cuneiform or spatulate to linear or setiform, ± membranous, sometimes all or partially wanting. <b>Pistillate</b> florets usually 1–8+, rarely 0; corollas whitish (inconspicuous), ± tubular. <b>Functionally</b> staminate florets 3–20+; corollas whitish to pinkish, funnelform, lobes 5, soon reflexed (filaments ± connate, anthers coherent or distinct). <b>Cypselae</b> plumply obovoid to pyriform, often ± obcompressed, sometimes scabrellous or hispidulous distally, usually ± gland-dotted; pappi 0. <b>x</b> = 18.</span><!--

-->{{Treatment/Body
|distribution=Mostly temperate North America;some subtropical;some introduced in Old World.
|discussion=<p>Species ca. 9 (7 in the flora).</p><!--
--><p>M. Bolick (1983), P. O. Karis (1995), and B. Miao et al. (1995, 1995b, 1995c) considered <i>Iva</i> in the sense of R. C. Jackson (1960) to include species that have closer relatives outside <i>Iva</i> in the broad sense than within. I agree and treat the extradited species in <i>Chorisiva</i>, <i>Cyclachaena</i>, <i>Hedosyne</i>, <i>Leuciva</i>, and <i>Oxytenia</i>.</p><!--
--><p>Ivas are wind pollinated, are related to the ragweeds (<i>Ambrosia</i> spp.), and may be similarly associated with pollen allergies.</p><!--
--><p>Records of <i>Iva</i> asperifolia Lessing from Florida are evidently based on specimens that are treated as members of <i>I. angustifolia</i>.</p>
|tables=
|references=
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Annuals (seldom persisting); leaf blades deltate, filiform, lanceolate, lance-linear, or ovate (rarely succulent or fleshy); heads in ± spiciform arrays; peduncles mostly 0.5–1 mm
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Perennials, subshrubs, or shrubs; leaf blades elliptic, lanceolate, oblanceolate, obovate, ovate, or spatulate (usually ± succulent or fleshy); heads in ± racemiform arrays; peduncles mostly 1–7 mm
|[[#key-0-4| > 4]]
|-id=key-0-2
|2
|Leaves petiolate, blades mostly deltate to lanceolate, margins toothed
|[[Iva annua|Iva annua]]
|-id=key-0-2
|2
|Leaves ± sessile, blades mostly lance-linear to filiform, margins entire
|[[#key-0-3| > 3]]
|-id=key-0-3
|3
|Involucres ± prismatically turbinate, 2.5–3 mm; outer phyllaries ± connate
|[[Iva angustifolia|Iva angustifolia]]
|-id=key-0-3
|3
|Involucres ± hemispheric, 1.5–2 mm; outer phyllaries distinct
|[[Iva microcephala|Iva microcephala]]
|-id=key-0-4
|4
|Subshrubs or shrubs, 50–350 cm; leaf blades ovate or elliptic to lanceolate, margins usually toothed
|[[Iva frutescens|Iva frutescens]]
|-id=key-0-4
|4
|Perennials or subshrubs, 10–50(–100) cm; leaf blades mostly obovate or elliptic to lanceolate, oblanceolate, or spatulate, margins usually entire, rarely toothed
|[[#key-0-5| > 5]]
|-id=key-0-5
|5
|Leaf blades glabrous; involucres campanulate to urceolate, 5–7+ mm; cypselae 4–5 mm
|[[Iva imbricata|Iva imbricata]]
|-id=key-0-5
|5
|Leaf blades usually strigose to scabrellous; involucres ± hemispheric, 2–3.5 mm; cypselae 2–3 mm
|[[#key-0-6| > 6]]
|-id=key-0-6
|6
|Aerial stems usually woody at bases; outer phyllaries distinct
|[[Iva hayesiana|Iva hayesiana]]
|-id=key-0-6
|6
|Aerial stems usually herbaceous; outer phyllaries ± connate
|[[Iva axillaris|Iva axillaris]]
|}
</div></div><!--

-->{{#Taxon:
name=Iva
|author=John L. Strother
|authority=Linnaeus
|rank=genus
|parent rank=subtribe
|synonyms=
|basionyms=
|family=Asteraceae
|distribution=Mostly temperate North America;some subtropical;some introduced in Old World.
|reference=None
|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_41.xml
|tribe=Asteraceae tribe Heliantheae
|subtribe=Asteraceae (tribe Heliantheae) subtribe Ambrosiinae
|genus=Iva
}}<!--

-->[[Category:Treatment]][[Category:Asteraceae (tribe Heliantheae) subtribe Ambrosiinae]]