View source for Tripleurospermum

{{Treatment/ID
|accepted_name=Tripleurospermum
|accepted_authority=Schultz-Bipontinus
|publications={{Treatment/Publication
|title=Tanaceteen,
|place=31. 1844
|year=1844
}}
|common_names=Mayweed
|basionyms=
|synonyms=
|hierarchy=Asteraceae;Asteraceae tribe Anthemideae;Tripleurospermum
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Anthemideae]]</div><div class="higher-taxon"><small>genus</small>[[Tripleurospermum]]</div></div>
|etymology=Greek tri- , three-, pleuro- , ribbed, and sperma, seed, alluding to strongly 3-ribbed cypselae
|volume=Volume 19
|mention_page=page 31, 488, 541, 550
|treatment_page=page 548
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Annuals,</b> biennials, or perennials, 5–80 cm (taprooted; scentless or nearly so). <b>Stems</b> 1–5+, usually erect or ascending, sometimes procumbent, branched or simple, glabrous or sparsely hairy (hairs basifixed). <b>Leaves</b> (not marcescent) basal (usually withering by flowering) and cauline; petiolate or sessile; blades oblong, 1–3-pinnately lobed, ultimate margins crenate or serrate, faces glabrous or sparsely hairy. <b>Heads</b> radiate [discoid or disciform], borne singly or in corymbiform arrays. <b>Involucres</b> hemispheric to patelliform, 8–12+ mm diam. <b>Phyllaries</b> persistent, 28–60+ in 2–5 series, distinct, broadly ovate, unequal to subequal, margins and apices (pale to dark brown or black) narrowly to widely scarious (abaxial faces glabrous). <b>Receptacles</b> convex to conic (± solid), epaleate. <b>Ray</b> florets [0] 10–34+, pistillate, fertile; corollas white [seldom pinkish], laminae mostly oblong. <b>Disc</b> florets 300–500, bisexual, fertile; corollas yellow [greenish], tubes cylindric (sessile-glandular), throats narrowly campanulate (cylindric or compressed), lobes 5, deltate (with resin sacs). <b>Cypselae</b> trigonous, ± compressed (apices truncate), ribs 3–5 (0–2 abaxial, 2 lateral, 1 adaxial, usually whitish, relatively thick, smooth), faces often rugose or tuberculate abaxially and between ribs and glabrous (pericarps sometimes with myxogenic cells and usually 2–3, sometimes 1–5, abaxial-apical resin sacs; embryo sac development tetrasporic); pappi 0 [coroniform or each an adaxial auricle]. <b>x</b> = 9.</span><!--

-->{{Treatment/Body
|distribution=North America;Eurasia;North Africa;introduced in New Zealand;one species widespread as a weed.
|discussion=<p>Species ca. 40 (2 in the flora).</p><!--
--><p><i>Tripleurospermum</i> often has been included within <i>Matricaria</i>. It is distinguished from the latter by 3-ribbed cypselae with 2 abaxial-apical resin sacs versus 5-ribbed cypselae without apical sacs, and by production of 7-glycoside flavonols versus 3-glycosides (K. Bremer and C. J. Humphries 1993). C. Oberprieler (2001) showed that <i>Tripleurospermum</i> is closely related to <i>Anthemis</i> in the strict sense and not to <i>Matricaria</i>. This is supported by the tetrasporic embryo sac shared by <i>Tripleurospermum</i> and <i>Anthemis</i> (versus monosporic in <i>Matricaria</i> and other anthemid genera), similarity of karyotype, and the presence in both genera of matricaria ester in the polyacetylene pathway, otherwise unknown in the tribe.</p><!--
--><p>Although W. L. Applequist (2002) favored a single species, <i>Tripleurospermum maritimum</i>, for the three taxa (as subspecies) present in North America, based in large parts on the findings of A. Vaarama (1953) on crossing ability among these taxa, on the existence of hybrid populations, and on the (mistaken) supposition that they form a polyploid series, some recent authors (e.g., Q. O. N. Kay 1976b, 1994; A. R. Clapham et al. 1987; E. G. Voss 1972–1996, vol. 3) have maintained two species based on morphologic characters, notably perennial versus annual habit, spacing of ribs (closer versus wider), elongate versus ± circular resin sacs on cypselae, relative infrequency of hybrid populations, and relative sterility of some hybrid individuals, as well as both species harboring diploid and tetraploid populations (Clapham et al.; Kay 1994). Success in interbreeding among plants does not always indicate conspecific status. In North America, authors such as M. L. Fernald (1950) and H. A. Gleason and A. Cronquist (1991) treated (in <i>Matricaria</i>) <i>T. inodorum</i> and <i>T. maritimum </i>subsp.<i> maritimum</i> as a single species with varieties or as a single entity, resulting in confusion about the distinctness of the two taxa in their ranges of introduction, and also difficulty in recognizing the presence of <i>T. inodorum</i> in areas where <i>T. maritimum </i>subsp.<i> maritimum</i> is present in coastal northeastern United States (e.g., D. W. Magee and H. E. Ahles 1999). N. N. Tzvelev (2002b) segregated the subspecies of <i>T. maritimum</i> as species; under his scheme, three species are present in North America: <i>T. inodorum</i>, <i>T. maritimum</i> in the strict sense, and <i>T. hookeri</i> (= <i>T. maritimum </i>subsp.<i> phaeocephalum</i>). Pending further taxonomic work on this complex, I have here retained the taxonomy (except generic assignment) adopted by Kay (1976b), with two species, one including two subspecies.</p>
|tables=
|references=
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Annuals (sometimes biennials or perennials); stems ascending to erect; ultimate leaf lobes not fleshy; cypselae: ribs separated by at least 1/3 their widths, resin glands ± circular (lengths mostly 1–1.5 times widths); scarious margins of phyllaries light brown, relatively narrow; cultivated and waste grounds
|[[Tripleurospermum inodorum|Tripleurospermum inodorum]]
|-id=key-0-1
|1
|Perennials (or biennials); stems usually procumbent, sometimes ascending; ultimate leaf lobes fleshy; cypselae: ribs contiguous or separated by less than 1/4 their widths, resin glands ± elongate (lengths 2+ times widths); scarious margins of phyllaries pale to dark brown, relatively wide; open coastal habitats
|[[Tripleurospermum maritimum|Tripleurospermum maritimum]]
|}
</div></div><!--

-->{{#Taxon:
name=Tripleurospermum
|author=Luc Brouillet
|authority=Schultz-Bipontinus
|rank=genus
|parent rank=tribe
|synonyms=
|basionyms=
|family=Asteraceae
|illustrator=Linny Heagy
|illustration copyright=Flora of North America Association
|distribution=North America;Eurasia;North Africa;introduced in New Zealand;one species widespread as a weed.
|reference=None
|publication title=Tanaceteen,
|publication year=1844
|special status=
|source xml=https://bitbucket.org/aafc-mbb/fna-data-curation/src/2e0870ddd59836b60bcf96646a41e87ea5a5943a/coarse_grained_fna_xml/V19-20-21/V19_955.xml
|tribe=Asteraceae tribe Anthemideae
|genus=Tripleurospermum
}}<!--

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