View source for Arida

{{Treatment/ID
|accepted_name=Arida
|accepted_authority=(R. L. Hartman) D. R. Morgan & R. L. Hartman
|publications={{Treatment/Publication
|title=Sida
|place=20: 1410. 2003
|year=2003
}}
|common_names=Desert tansy-aster
|basionyms={{Treatment/ID/Basionym
|name=Machaeranthera sect. Arida
|authority=R. L. Hartman
|rank=section
|publication_title=Phytologia
|publication_place=68: 446. 1990
}}
|synonyms=
|hierarchy=Asteraceae;Asteraceae tribe Astereae;Arida
|hierarchy_nav=<div class="higher-taxa"><div class="higher-taxon"><small>family</small>[[Asteraceae]]</div><div class="higher-taxon"><small>tribe</small>[[Asteraceae tribe Astereae]]</div><div class="higher-taxon"><small>genus</small>[[Arida]]</div></div>
|etymology=Latin aridus, dry, alluding to xeric habitat typical of members
|volume=Volume 20
|mention_page=page 6, 12, 18, 394, 402, 403, 462
|treatment_page=page 401
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Annuals,</b> perennials, or subshrubs, 10–60(–90) cm; usually taprooted, sometimes rhizomatous. <b>Stems</b> erect to ascending or sprawling, often much branched, glabrous or hairy, sometimes stipitate-glandular or gland-dotted. <b>Leaves</b> basal (sometimes withering by flowering) and cauline; alternate; petiolate (basal) or sessile (cauline; sometimes succulent); basal blades 1-nerved, linear to lanceolate, oblanceolate or obovate, cauline lanceolate to scalelike (bases tapered to clasping), margins entire, dentate, lacerate to deeply pinnatifid, or 2-pinnatifid (apices, including of lobes and teeth, apiculate to bristle-tipped, bristles 0.1–1 mm), faces glabrous or densely hairy, sometimes stipitate-glandular. <b>Heads</b> radiate or discoid (<i>A. carnosa</i>), borne singly (terminal), or in cymiform or corymbiform arrays. <b>Involucres</b> turbinate to depressed-hemispheric, (3–12 ×) 4–16 mm. <b>Phyllaries</b> 40–150+ in 4–8 series, appressed, spreading, or reflexed, 1-nerved (flat to rounded or weakly keeled), linear-lanceolate to oblong-lanceolate, unequal, bases indurate to herbaceous, apices herbaceous, margins sometimes scarious, faces glabrous or moderately to densely hairy, sometimes stipitate-glandular. <b>Receptacles</b> convex, indistinctly pitted (pit borders ± chartaceous, laciniate 0.1–0.5 mm, in <i>A. blepharophylla</i>), epaleate. <b>Ray</b> florets 0 (<i>A. carnosa</i>) or 8–80+, pistillate, fertile; corollas light to dark blue. <b>Disc</b> florets 12–100+, bisexual, fertile; corollas yellow, tubes 1/4–1/2 times ± funnelform throats (usually glabrous), lobes 5, erect, triangular (glabrous to minutely hairy). <b>Cypselae</b> ± dimorphic, narrowly oblong (thin-walled), 8–13-nerved per face (nerves filiform), sparsely to densely sericeous; ray cypselae (if present) obscurely 3-sided, rounded abaxially, disc ones slightly compressed laterally; pappi persistent, of 20–40, white or whitish (tawny in <i>A. blepharophylla</i>), barbellulate, apically attenuate bristles in 2–3 series (at most ± flattened and wider near sometimes slightly overlapping bases); ray lengths 1/3 to ± equaling disc. <b>x</b> = 5.</span><!--

-->{{Treatment/Body
|distribution=Desert regions;sw United States;n Mexico.
|discussion=<p>Species 9 (6 in the flora).</p><!--
--><p><i>Arida</i> belongs to a group of taxa once included within a broadly circumscribed <i>Machaeranthera</i> containing more than 36 species. This genus was generally distinguished by its taproots, spiny-toothed pinnatifid leaves, bristly-tipped phyllaries, blue ray corollas, epappose ray florets, and chromosome numbers of n = 4, 5, or 6 (A. Cronquist and D. D. Keck 1957; R. L. Hartman 1990; L. H. Shinners 1950b; B. L. Turner 1987b; Turner and D. B. Horne 1964). <i>Arida</i> was recognized as a section of <i>Machaeranthera</i> with epappose ray florets, unequal phyllaries, and a chromosome number of n = 5. Studies incorporating data from cpDNA restriction site analysis (D. R. Morgan and B. B. Simpson 1992) indicated that section <i>Psilactis</i> was not closely related to the other taxa and it was removed (Morgan 1993). Further studies utilizing DNA sequence data (Morgan 1997) suggested that other genera, such as <i>Oönopsis</i>, <i>Pyrrocoma</i>, and <i>Xanthisma</i>, were closely related to various parts of <i>Machaeranthera</i>. The combined phylogenetic information from molecular, morphologic, cytologic, and flavonoid analyses did not support recent taxonomies, so a new one was proposed by Morgan and Hartman (2003). <i>Machaeranthera</i> was reduced to two species, and the remaining taxa were distributed in <i>Xanthisma</i>, <i>Dieteria</i>, and <i>Arida</i>.</p><!--
--><p>Data from chloroplast DNA restriction sites and nuclear ETS sequences support a close relationship between <i>Arida parviflora</i>, A. turneri, both with pinnate or 2-pinnate leaves, <i>A. riparia</i>, and <i>A. blepharophylla</i> (D. R. Morgan 2003; Morgan and B. B. Simpson 1992). Conflicts between the two data sets were attributed to reticulate evolution resulting from occasional intergeneric crosses. <i>Arida blepharophylla</i> is somewhat unusual within the genus in being a short-lived perennial with rhizomes, basal rosettes of leaves, and receptacular scales (Morgan and R. L. Hartman 2003). These characters are similar to those found in <i>Xanthisma</i> and with these morphologic features as well as chloroplast versus nuclear DNA data, it may have evolved through intergeneric hybridization (Morgan 2003).</p>
|tables=
|references=
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Ray cypselae epappose (except in occasional plants)
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Ray cypselae pappose or ray florets 0 (in A. carnosa)
|[[#key-0-4| > 4]]
|-id=key-0-2
|2
|Midstems densely hispiduloso-glandular; s Arizona, s California, s Nevada, n Sonora (Mexico)
|[[Arida arizonica|Arida arizonica]]
|-id=key-0-2
|2
|Midstems glabrous or sparsely gland-dotted
|[[#key-0-3| > 3]]
|-id=key-0-3
|3
|Cauline leaf blades entire or toothed; w Texas
|[[Arida mattturneri|Arida mattturneri]]
|-id=key-0-3
|3
|Cauline leaf blades deeply pinnatifid; e Arizona, s Colorado, New Mexico, Utah, Chihuahua and Coahuila (Mexico)
|[[Arida parviflora|Arida parviflora]]
|-id=key-0-4
|4
|Leaves (at least some) pinnatifid to 2-pinnatifid
|[[Arida parviflora|Arida parviflora]]
|-id=key-0-4
|4
|Leaves entire or toothed
|[[#key-0-5| > 5]]
|-id=key-0-5
|5
|Ray florets 0
|[[Arida carnosa|Arida carnosa]]
|-id=key-0-5
|5
|Ray florets present.
|[[#key-0-6| > 6]]
|-id=key-0-6
|6
|Perennials, rhizomatous, forming vegetative rosettes; leaf margins entire with 8–20 cilia per side (cilia 0.4–1.5 mm); involucres broadly turbinate, 5–8 mm wide (fresh); phyllaries oblong to oblanceolate or obovate, broadly acute to short-acuminate
|[[Arida blepharophylla|Arida blepharophylla]]
|-id=key-0-6
|6
|Annuals; leaf margins entire, eciliate or with 1–8 cilia per side; involucres hemispheric, 10–16 mm wide (fresh); phyllaries linear-lanceolate, acute to acuminate
|[[Arida riparia|Arida riparia]]
|}
</div></div><!--

-->{{#Taxon:
name=Arida
|author=Ronald L. Hartman;David J. Bogler
|authority=(R. L. Hartman) D. R. Morgan & R. L. Hartman
|rank=genus
|parent rank=tribe
|synonyms=
|basionyms=Machaeranthera sect. Arida
|family=Asteraceae
|illustrator=Bee F. Gunn
|illustration copyright=Flora of North America Association
|distribution=Desert regions;sw United States;n Mexico.
|reference=None
|publication title=Sida
|publication year=2003
|special status=
|source xml=https://jpend@bitbucket.org/aafc-mbb/fna-data-curation.git/src/f50eec43f223ca0e34566be0b046453a0960e173/coarse_grained_fna_xml/V19-20-21/V20_920.xml
|tribe=Asteraceae tribe Astereae
|genus=Arida
}}<!--

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