View source for Tetraneuris

{{Treatment/ID
|accepted_name=Tetraneuris
|accepted_authority=Greene
|publications={{Treatment/Publication
|title=Pittonia
|place=3: 265. 1898
|year=1898
}}
|common_names=Bitterweed
|basionyms=
|synonyms=
|hierarchy=Asteraceae;Asteraceae tribe Heliantheae;Asteraceae (tribe Heliantheae) subtribe Gaillardiinae;Tetraneuris
|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 Gaillardiinae]]</div><div class="higher-taxon"><small>genus</small>[[Tetraneuris]]</div></div>
|etymology=Greek tetra, four, and neuron, nerve, alluding to venation of ray floret corollas
|volume=Volume 21
|mention_page=page 415, 416, 437
|treatment_page=page 447
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Annuals </b>or perennials, 2–50+ cm (perennials with ± branched, woody caudices). <b>Stems</b> 1–60, erect or ± decumbent, unbranched or sparingly branched distally. <b>Leaves</b> all basal, or basal-proximal, or basal and cauline; alternate; petiolate or sessile; blades (usually with distinct midribs) mostly oblanceolate to linear or filiform, sometimes lobed, ultimate margins usually entire, sometimes toothed, faces glabrous or ± hairy, eglandular or ± gland-dotted. <b>Heads</b> radiate or discoid, borne singly or in paniculiform to corymbiform or fastigiate arrays. <b>Involucres</b> hemispheric to campanulate 6–20 mm diam. <b>Phyllaries</b> 11–60+ in 3 series (mostly spreading to erect in fruit, distinct, herbaceous; outer with or without scarious margins, abaxial faces ± hairy; mid usually same number as, alternating with, and similar to outer, almost always with ± scarious margins; inner narrower than others, margins scarious). <b>Receptacles</b> hemispheric to conic, shallowly pitted or smooth, epaleate. <b>Ray</b> florets 0 or 7–27, pistillate, fertile; corollas (usually marcescent) yellow (laminae fan-shaped to oblanceolate, usually 3-lobed). <b>Disc</b> florets 20–250+, bisexual, fertile; corollas yellow proximally, yellow or purplish distally, tubes shorter than cylindric to cylindro-campanulate throats, lobes 5, ± deltate. <b>Cypselae</b> ± obpyramidal, moderately to densely hairy; pappi persistent, of 4–8 usually aristate, scales. <b>x</b> = 15.</span><!--

-->{{Treatment/Body
|distribution=North America;Mexico.
|discussion=<p>Species 9 (9 in the flora).</p><!--
--><p>Here, strigoso-canescent refers to often silvery induments (hairs tightly appressed, relatively short, 1–1.5 mm) of <i>Tetraneuris argentea</i> and <i>T. acaulis </i>var.<i> acaulis</i>. Such induments contrast with lanuginose or sericeous induments (hairs spreading, ca 1.5–3 mm) in other taxa, including <i>T. ivesiana</i> and the other three varieties of <i>T. acaulis</i>.</p>
|tables=
|references=
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Annuals
|[[Tetraneuris linearifolia|Tetraneuris linearifolia]]
|-id=key-0-1
|1
|Perennials (with caudices)
|[[#key-0-2| > 2]]
|-id=key-0-2
|2
|Caudices: branches not notably thickened distally; leaves all basal-proximal (not tightly clustered, internodes often evident)
|[[#key-0-3| > 3]]
|-id=key-0-2
|2
|Caudices: branches notably thickened distally; leaves all basal or basal and cauline (basal leaves tightly clustered, internodes usually not evident)
|[[#key-0-4| > 4]]
|-id=key-0-3
|3
|Stems erect; leaves sparsely to densely hairy, not woolly; Colorado, Kansas,Nebraska, New Mexico, Oklahoma, Texas
|[[Tetraneuris scaposa|Tetraneuris scaposa]]
|-id=key-0-3
|3
|Stems erect or ± decumbent; leaves moderately to densely woolly; s Texas
|[[Tetraneuris turneri|Tetraneuris turneri]]
|-id=key-0-4
|4
|Leaves basal and cauline
|[[#key-0-5| > 5]]
|-id=key-0-4
|4
|Leaves all basal
|[[#key-0-6| > 6]]
|-id=key-0-5
|5
|Leaf blades ± densely strigoso-canescent
|[[Tetraneuris argentea|Tetraneuris argentea]]
|-id=key-0-5
|5
|Leaf blades glabrous or sparsely to moderately lanuginose to sericeous
|[[Tetraneuris ivesiana|Tetraneuris ivesiana]]
|-id=key-0-6
|6
|Ray florets 0 (leaves densely hairy, not strigoso-canescent; Yavapai County,Arizona)
|[[Tetraneuris verdiensis|Tetraneuris verdiensis]]
|-id=key-0-6
|6
|Ray florets usually 7–27 (if 0, leaves strigoso-canescent; widespread)
|[[#key-0-7| > 7]]
|-id=key-0-7
|7
|Rays 14–27; pappus scales usually non-aristate; Ontario, Illinois, Ohio
|[[Tetraneuris herbacea|Tetraneuris herbacea]]
|-id=key-0-7
|7
|Rays 7–15(–21); pappus scales aristate; North Dakota to Texas and west
|[[#key-0-8| > 8]]
|-id=key-0-8
|8
|Leaves (midribs usually distinct) glabrous or usually sparsely, sometimes moderately or densely hairy (not strigoso-canescent or sericeous), gland-dotted; outer phyllaries 4–8, margins (0.3–)0.5–1.2 mm wide, usuallyconspicuously scarious
|[[Tetraneuris torreyana|Tetraneuris torreyana]]
|-id=key-0-8
|8
|Leaves (midribs not very distinct) glabrous or ± hairy, often lanuginose, sericeous, or strigoso-canescent, eglandular or ± gland-dotted; outer phyllaries 6–12, margins 0–0.4 mm wide, sometimes slightly scarious
|[[Tetraneuris acaulis|Tetraneuris acaulis]]
|}
</div></div><!--

-->{{#Taxon:
name=Tetraneuris
|author=Mark W. Bierner;Billie L. Turner
|authority=Greene
|rank=genus
|parent rank=subtribe
|synonyms=
|basionyms=
|family=Asteraceae
|distribution=North America;Mexico.
|reference=None
|publication title=Pittonia
|publication year=1898
|special status=
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/eaa6e58056e40c9ef614d8f47aea294977a1a5e9/coarse_grained_fna_xml/V19-20-21/V21_1120.xml
|tribe=Asteraceae tribe Heliantheae
|subtribe=Asteraceae (tribe Heliantheae) subtribe Gaillardiinae
|genus=Tetraneuris
}}<!--

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