View source for Tetradymia

{{Treatment/ID
|accepted_name=Tetradymia
|accepted_authority=de Candolle in A. P. de Candolle and A. L. P. P. de Candolle
|publications={{Treatment/Publication
|title=in A. P. de Candolle and A. L. P. P. de Candolle, Prodr.
|place=6: 440. 1838
|year=1838
}}
|basionyms=
|synonyms=
|hierarchy=Asteraceae;Asteraceae tribe Senecioneae;Tetradymia
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Senecioneae]]</div><div class="higher-taxon"><small>genus</small>[[Tetradymia]]</div></div>
|etymology=Greek tetradymos, fourfold, evidently alluding to numbers of phyllaries and florets in heads of original species
|volume=Volume 20
|mention_page=page 540, 542
|treatment_page=page 629
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Shrubs,</b> mostly 30–200 cm. <b>Stems</b> 1–5+, erect to spreading (tomentose to pannose or glabrous, often spiny). <b>Leaves</b> (usually with fascicles of secondary leaves in axils of the primary; primaries sometimes becoming spines) cauline; alternate; sessile (or obscurely petiolate); blades obscurely palmately nerved (usually 1-nerved), linear to filiform, narrowly lanceolate, or oblanceolate, margins entire, faces glabrous or lanate to tomentose, sometimes glabrescent. <b>Heads</b> discoid, (1–3) in distil axils or (3–8) in corymbiform clusters. <b>Calyculi</b> 0. <b>Involucres</b> turbinate to cylindric or hemispheric, 3–10+ mm diam. <b>Phyllaries</b> persistent, 4–6 in 1–2 series, erect, distinct, mostly oblong to ovate or lanceolate, equal or subequal, margins obscurely scarious. <b>Receptacles</b> flat, foveolate, epaleate. <b>Ray</b> florets 0. <b>Disc</b> florets 4–9, bisexual, fertile; corollas cream to bright yellow, tubes longer than funnelform or abruptly dilated throats, lobes 5, recurved, linear to lanceolate; style branches stigmatic in 2 lines, apices usually truncate to rounded-truncate, sometimes truncate-penicillate (appendages essentially 0). <b>Cypselae</b> prismatic to obconic or fusiform, obscurely 5-ribbed, glabrous or hirsute to densely pilose (hairs often obscuring pappi); pappi 0 or of 70–150 bristles or of 20–30, white to stramineous, subulate to setiform scales. <b>x</b> = 30.</span><!--

-->{{Treatment/Body
|distribution=w North America;nw Mexico.
|discussion=<p>Species 10 (10 in the flora).</p>
|tables=
|references={{Treatment/Reference
|id=strother1974a
|text=Strother, J. L. 1974. Taxonomy of Tetradymia (Compositae: Senecioneae). Brittonia 26: 177–202.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Indumentum of stems evenly pannose; cypselae with white hairs that obscure or replace pappi; pappi 0 or of 20–30, subulate to setiform scales
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Indumentum of stems interrupted by linear, tomentose to nearly glabrous streaks; cypselae glabrous or with induments shorter than cypselae, not obscuring or replacing pappi; pappi of 70–150 bristles
|[[#key-0-5| > 5]]
|-id=key-0-2
|2
|Primary leaves forming rigid spines; heads in clusters of 1–3 (in axils of spines)
|[[#key-0-3| > 3]]
|-id=key-0-2
|2
|Primary leaves flaccid or stiff and pungent, not forming spines; heads in corymbiform clusters of 3–7
|[[#key-0-4| > 4]]
|-id=key-0-3
|3
|Spines straight, 10–50 mm, glabrescent; involucres mostly turbinate, 7–9 mm; cypselae 4–5 mm
|[[Tetradymia axillaris|Tetradymia axillaris]]
|-id=key-0-3
|3
|Spines recurved, 5–25 mm, tomentose; involucres mostly campanulate, 8–12 mm; cypselae 6–8 mm
|[[Tetradymia spinosa|Tetradymia spinosa]]
|-id=key-0-4
|4
|Blades of primary leaves lance-linear to spatulate, becoming stiff, pungent; florets 5–8; cypselae 6–8 mm, epappose
|[[Tetradymia comosa|Tetradymia comosa]]
|-id=key-0-4
|4
|Blades of primary leaves filiform, flaccid; florets 4(–5); cypselae 4–6 mm, pappose
|[[Tetradymia tetrameres|Tetradymia tetrameres]]
|-id=key-0-5
|5
|Primary leaves not forming spines
|[[#key-0-6| > 6]]
|-id=key-0-5
|5
|Primary leaves becoming rigid, ± persistent spines
|[[#key-0-8| > 8]]
|-id=key-0-6
|6
|Blades of primary leaves subulate and ± appressed to stems, contrasting with subtended clavate, glabrous or glabrescent blades of secondary leaves
|[[Tetradymia glabrata|Tetradymia glabrata]]
|-id=key-0-6
|6
|Blades of primary leaves filiform to spatulate, spreading, similar to subtended tomentose to sericeous blades of secondary leaves
|[[#key-0-7| > 7]]
|-id=key-0-7
|7
|Blades of primary leaves spatulate to lanceolate; pappus bristles weakly, if at all, distally dilated
|[[Tetradymia canescens|Tetradymia canescens]]
|-id=key-0-7
|7
|Blades of primary leaves linear to filiform; pappus bristles distally dilated
|[[Tetradymia filifolia|Tetradymia filifolia]]
|-id=key-0-8
|8
|Blades of secondary leaves filiform to clavate; cypselae glabrous
|[[Tetradymia argyraea|Tetradymia argyraea]]
|-id=key-0-8
|8
|Blades of secondary leaves spatulate; cypselae densely hirsute or villous to densely pilose
|[[#key-0-9| > 9]]
|-id=key-0-9
|9
|Blades of secondary leaves greenish, usually villous, sometimes glabrescent; florets mostly 4; cypselae 4–6 mm, densely hirsute
|[[Tetradymia nuttallii|Tetradymia nuttallii]]
|-id=key-0-9
|9
|Blades of secondary leaves silvery sericeous; florets mostly 5; cypselae 6–8 mm, villous to densely pilose
|[[Tetradymia stenolepis|Tetradymia stenolepis]]
|}
</div></div><!--

-->{{#Taxon:
name=Tetradymia
|author=John L. Strother
|authority=de Candolle in A. P. de Candolle and A. L. P. P. de Candolle
|rank=genus
|parent rank=tribe
|synonyms=
|basionyms=
|family=Asteraceae
|distribution=w North America;nw Mexico.
|reference=strother1974a
|publication title=in A. P. de Candolle and A. L. P. P. de Candolle, Prodr.
|publication year=1838
|special status=
|source xml=https://bibilujan@bitbucket.org/aafc-mbb/fna-data-curation.git/src/bb6b7e3a7de7d3b7888a1ad48c7fd8f5c722d8d6/coarse_grained_fna_xml/V19-20-21/V20_1413.xml
|tribe=Asteraceae tribe Senecioneae
|genus=Tetradymia
}}<!--

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