View source for Tithonia

{{Treatment/ID
|accepted_name=Tithonia
|accepted_authority=Desfontaines ex Jussieu
|publications={{Treatment/Publication
|title=Gen. Pl.,
|place=189. 1789
|year=1789
}}
|common_names=Sunflowerweed
|basionyms=
|synonyms=
|hierarchy=Asteraceae;Asteraceae tribe Heliantheae;Asteraceae (tribe Heliantheae) subtribe Helianthinae;Tithonia
|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 Helianthinae]]</div><div class="higher-taxon"><small>genus</small>[[Tithonia]]</div></div>
|etymology=From Greek mythology, Tithonus, son of Laomedon and consort of Aurora, symbolic of old age; perhaps alluding to gray to white induments of some plants
|volume=Volume 21
|mention_page=page 135
|treatment_page=page 138
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Annuals,</b> perennials, subshrubs, or shrubs [trees], 70–500[–700] cm. <b>Stems</b> erect, branched. <b>Leaves</b> all or mostly cauline; opposite (proximal) or mostly alternate; petiolate or sessile; blades often (1-), 3-, or 5-nerved, mostly deltate or pentagonal [lanceolate, linear], sometimes 3- or 5-lobed, bases ± truncate or auriculate [attenuate] (sometimes decurrent onto petioles), ultimate margins serrate to crenate, faces glabrate, ± hirsute, pilose, soft-pubescent, or villous, often gland-dotted. <b>Heads</b> borne singly (peduncles usually distally dilated, fistulose). <b>Involucres</b> campanulate to hemispheric, 10–20+ mm diam. <b>Phyllaries</b> persistent, 12–28+ in 2–5 series (linear to broadly rounded, unequal to subequal, apices acute to rounded). <b>Receptacles</b> hemispheric to convex, paleate (paleae persistent, embracing cypselae, striate, ± 3-toothed, middle teeth larger, stiff, acute or acuminate to aristate). <b>Ray</b> florets 8–30, neuter; corollas yellow or orange. <b>Disc</b> florets 40–120[–200+], bisexual, fertile; corollas yellow, tubes shorter than throats (bases of throats bulbous and hairy), lobes 5, ± triangular (anthers black, brown, or tan, bases cordate-sagittate, appendages ovate; style branches relatively slender, appendages penicillate or lanceolate to attenuate). <b>Cypselae</b> (black or brown) ± compressed or flattened, often 3- or 4-angled or biconvex, ± cuneiform in silhouette (sometimes with basal elaiosomes); pappi 0, or ± coroniform (of ± connate scales, 1–2 scales sometimes subulate to aristate). <b>x</b> = 17.</span><!--

-->{{Treatment/Body
|distribution=sw United States;Mexico;Central America;introduced in se United States;West Indies;South America;and Old World.
|discussion=<p>Species 11 (3 in the flora).</p>
|tables=
|references={{Treatment/Reference
|id=la1982a
|text=La Duke, J. C. 1982. Revision of Tithonia. Rhodora 84: 453–522.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Perennials, subshrubs, or shrubs; phyllaries 16–28; ray laminae 48–69 mm; disc florets 80–120+; cypselae 4–6 mm
|[[Tithonia diversifolia|Tithonia diversifolia]]
|-id=key-0-1
|1
|Annuals; phyllaries 12–16; ray laminae 9–15 or 20–33 mm; disc florets 40–60 or 60–90; cypselae 5–9 mm
|[[#key-0-2| > 2]]
|-id=key-0-2
|2
|Leaf blades ± deltate to pentagonal, often 3- or 5-lobed, abaxial faces soft-pubescent; rays usually orange, rarely yellow, laminae 20–33 × 6–17 mm
|[[Tithonia rotundifolia|Tithonia rotundifolia]]
|-id=key-0-2
|2
|Leaf blades mostly deltate, rarely, if ever, lobed, abaxial faces sparsely hirsute (hairs larger on veins); rays yellow, laminae 9–15 × 4–6 mm
|[[Tithonia thurberi|Tithonia thurberi]]
|}
</div></div><!--

-->{{#Taxon:
name=Tithonia
|author=John C. La Duke
|authority=Desfontaines ex Jussieu
|rank=genus
|parent rank=subtribe
|synonyms=
|basionyms=
|family=Asteraceae
|distribution=sw United States;Mexico;Central America;introduced in se United States;West Indies;South America;and Old World.
|reference=la1982a
|publication title=Gen. Pl.,
|publication year=1789
|special status=
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/f6b125a955440c0872999024f038d74684f65921/coarse_grained_fna_xml/V19-20-21/V21_335.xml
|tribe=Asteraceae tribe Heliantheae
|subtribe=Asteraceae (tribe Heliantheae) subtribe Helianthinae
|genus=Tithonia
}}<!--

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