View source for Lasthenia

{{Treatment/ID
|accepted_name=Lasthenia
|accepted_authority=Cassini
|publications={{Treatment/Publication
|title=Opusc. Phytol.
|place=3: 88. 1834
|year=1834
}}
|common_names=Goldfields
|basionyms=
|synonyms=
|hierarchy=Asteraceae;Asteraceae tribe Heliantheae;Asteraceae (tribe Heliantheae) subtribe Baeriinae;Lasthenia
|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 Baeriinae]]</div><div class="higher-taxon"><small>genus</small>[[Lasthenia]]</div></div>
|etymology=Greek, for a student of Plato, said to have been a woman who dressed as a man
|volume=Volume 21
|mention_page=page 255, 335, 337, 338, 339, 340, 341
|treatment_page=page 336
}}<!--

--><span class="statement" id="st-undefined" data-properties=""><b>Annuals </b>(perennials), to 40(–60) cm (taprooted or roots fibrous, fleshy and clustered in <i>Lasthenia californica </i>subsp.<i> bakeri</i>). <b>Stems</b> usually erect, sometimes decumbent, prostrate, or sprawling, simple or branched (usually distally, often proximally in decumbent plants). <b>Leaves</b> mostly cauline; opposite; petiolate or sessile; blades usually linear, often 1(–2)-pinnately lobed, ultimate margins entire or toothed, faces glabrous or hairy. <b>Heads</b> usually radiate, sometimes ± disciform (in <i>L. glaberrima</i> and <i>L. microglossa</i>), borne singly or in ± corymbiform arrays. <b>Involucres</b> obconic to hemispheric, 3–5+ mm diam. <b>Phyllaries</b> usually persistent, sometimes falling with cypselae, 4–18 in 1(–2) series (usually ± erect in fruit, distinct or ± connate, narrowly oblong to broadly ovate, mostly herbaceous, bases flat or weakly cupped, faces not woolly, except sometimes in <i>L. minor</i> and <i>L. platycarpha</i>). <b>Receptacles</b> hemispheric to narrowly conic or subulate, smooth, papillate, or pitted, glabrous or hairy, epaleate. <b>Ray</b> florets 4–16, pistillate, fertile; corollas yellow to orangish (sometimes white in <i>L. debilis</i>, often somewhat darker proximally, laminae rarely lacking in <i>L. glaberrima</i> and <i>L. microglossa</i>). <b>Disc</b> florets 5–100+, bisexual, fertile; corollas yellow to orangish (sometimes white in <i>L. debilis</i>), tubes shorter than or about equaling funnelform or campanulate throats, lobes (4–)5, deltate. <b>Cypselae</b> (black to gray) usually cylindric to obovoid, glabrous or hairy, sometimes papillate (flattened, margins fringed with blunt, curved hairs in <i>L. chrysantha</i>); pappi 0, or of 1–12 erose, fimbriate, or laciniate, truncate or aristate scales (sometimes 2 kinds in combination on single cypselae). <b>x</b> = 8.</span><!--

-->{{Treatment/Body
|distribution=w North America;nw Mexico;South America (Chile).
|discussion=<p>Species 18 (17 in the flora).</p><!--
--><p>Lasthenias occur in a wide variety of habitats; some are particularly conspicuous members of vernal-pool floras. The characteristic rich, golden yellow color of <i>Lasthenia gracilis</i> can be seen to cover thousands of hectares of grasslands and open woodlands in early spring, giving the genus its common name. Relatively few taxa are widely distributed; most have relatively restricted distributions. Some are considered to be of conservation concern.</p><!--
--><p><i>Lasthenia glaberrima</i>, L. kunthii, <i>L. maritima</i>, and <i>L. microglossa</i> are self-pollinating; the rest are self-incompatible, obligate outcrossers. <i>Lasthenia ornduffii</i> and two subspecies of <i>L. californica</i> are perennial; the rest are spring annuals. It is not uncommon to find two <i>Lasthenia</i> species growing more or less sympatrically (in discrete populations).</p><!--
--><p>Most lasthenias show a wide latitude of morphologic response to environmental conditions. Growth of individual plants of <i>Lasthenia</i> is robust in good conditions; in unfavorable conditions, single stems terminating in relatively small heads with relatively few florets are produced. Other morphologic characters such as the degree of leaf dissection, leaf margin, and pappus elements sometimes are plastic.</p><!--
--><p>Circumscriptions of taxa here are based on R. Ornduff (1966b) with realignments proposed by R. Chan (2000). Sections are characterized by morphology, chromosome numbers, biochemistry, ecology, and molecular data.</p>
|tables=
|references={{Treatment/Reference
|id=chan2000a
|text=Chan, R. 2000. Molecular Systematics of the Goldfield Genus Lasthenia (Compositae: Heliantheae Sensu Lato). Ph.D. dissertation. University of California, Berkeley.
}}{{Treatment/Reference
|id=chan2001a
|text=Chan, R., B. G. Baldwin, and R. Ornduff. 2001. Goldfields revisited: A molecular phylogenetic perspective on the evolution of Lasthenia (Compositae: Heliantheae sensu lato). Int. J. Pl. Sci. 162: 1347–1360.
}}{{Treatment/Reference
|id=ornduff1966a
|text=Ornduff, R. 1966b. A biosystematic survey of the goldfield genus Lasthenia (Compositae: Helenieae). Univ. Calif. Publ. Bot. 40: 1–92.
}}
}}<!--

--><div class="treatment-key">
==Key==
<div class="treatment-key-group">
  
{| class="wikitable fna-keytable"
|-id=key-0-1
|1
|Phyllaries connate 2/3+ their lengths
|[[#key-0-2| > 2]]
|-id=key-0-1
|1
|Phyllaries distinct or connate 1/4–1/2 their lengths
|[[#key-0-3| > 3]]
|-id=key-0-2
|2
|Cypselae epappose
|[[Lasthenia sect. Hologymne|Lasthenia sect. Hologymne]]
|-id=key-0-2
|2
|Cypselae pappose
|[[Lasthenia sect. Lasthenia|Lasthenia sect. Lasthenia]]
|-id=key-0-3
|3
|Leaves entire or ± toothed (not pinnatifid); corolla floral pigments turning deep red in dilute aqueous alkali
|[[#key-0-4| > 4]]
|-id=key-0-3
|3
|Leaves (especially midstem) usually 1(–2)-pinnately lobed or -pinnatifid, sometimes entire; corolla floral pigments remaining yellow in dilute aqueous alkali
|[[#key-0-5| > 5]]
|-id=key-0-4
|4
|Ray laminae 2.5–16 mm; receptacles usually narrowly conic to conic (subulate in L. leptalea, ray laminae 2.5–5 mm)
|[[Lasthenia sect. Amphiachaenia|Lasthenia sect. Amphiachaenia]]
|-id=key-0-4
|4
|Ray laminae 0–1 mm (and anther appendages eglandular), or 3–5 mm; receptacles subulate
|[[Lasthenia sect. Burrielia|Lasthenia sect. Burrielia]]
|-id=key-0-5
|5
|Cypselae to 1.5 mm
|[[Lasthenia sect. Ornduffia|Lasthenia sect. Ornduffia]]
|-id=key-0-5
|5
|Cypselae 1.5–3.5 mm
|[[#key-0-6| > 6]]
|-id=key-0-6
|6
|Cypselae pappose (pappi of 4–6 lanceolate to ovate, aristate scales)
|[[Lasthenia sect. Platycarpha|Lasthenia sect. Platycarpha]]
|-id=key-0-6
|6
|Cypselae epappose or pappose (pappi of 2–12 lanceolate, ovate, subulate, aristate scales, sometimes plus 4–5+ shorter, truncate, fimbriate, or laciniate scales)
|[[Lasthenia sect. Ptilomeris|Lasthenia sect. Ptilomeris]]
|}
</div></div><!--

-->{{#Taxon:
name=Lasthenia
|author=Raymund Chan;Robert Ornduff†
|authority=Cassini
|rank=genus
|parent rank=subtribe
|synonyms=
|basionyms=
|family=Asteraceae
|distribution=w North America;nw Mexico;South America (Chile).
|reference=chan2000a;chan2001a;ornduff1966a
|publication title=Opusc. Phytol.
|publication year=1834
|special status=
|source xml=https://bitbucket.org/aafc-mbb/fna-data-curation/src/2e0870ddd59836b60bcf96646a41e87ea5a5943a/coarse_grained_fna_xml/V19-20-21/V21_840.xml
|tribe=Asteraceae tribe Heliantheae
|subtribe=Asteraceae (tribe Heliantheae) subtribe Baeriinae
|genus=Lasthenia
}}<!--

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