{{Short description|Genus of flowering plants}} {{Automatic taxobox |image = Tuctoria greenei.jpg |image_caption = ''Tuctoria greenei'' |display_parents = 3 |taxon = Tuctoria |authority = J.Reeder |type_species = ''Tuctoria fragilis'' |type_species_authority = (Swallen) J.Reeder |subdivision_ranks = Species |subdivision =''T. fragilis''<br> ''T. greenei''<br> ''T. mucronata'' }}
'''''Tuctoria''''' is a genus of three species of grass in the family Poaceae. '''Spiralgrass''' is a common name for plants in this genus.<ref>{{PLANTS|id=TUCTO|taxon=Tuctoria|accessdate=12 December 2015}}</ref> These are bunchgrass species that are found in vernal pools of central California and Baja California, Mexico. The plants are annuals that germinate under water in the spring and grow submerged for weeks. After the pools dry down, the grasses initiate a new set of foliage that lasts for one to two months until flowering and fruiting are complete.
==Taxonomy== The genus was circumscribed by John R. Reeder in 1982. Along with ''Orcuttia'' and ''Neostapfia'', ''Tuctoria'' is one of three genera in the tribe Orcuttieae, previously outlined by Reeder in 1965.<ref name="Reeder 1965"/> All three ''Tuctoria'' species were formerly assigned to ''Orcuttia'', the type genus of Orcuttieae. Reeder erected ''Tuctoria'' after determining that the three species were more closely related among themselves than to any of the other ''Orcuttia'' species. Shared features include chromosome numbers, the spiral arrangement of spikelets on the rachis, the absence of juvenile leaves, the presence of lodicules, and the presence of an epiblast in the seed embryos. The name ''Tuctoria'' is an anagram of ''Orcuttia''.<ref name="Reeder 1982"/>
Recent (2010) molecular phylogenetic analysis suggests that ''Tuctoria'' is not monophyletic as currently circumscribed, and is in need of taxonomic revision.<ref name="Boykin 2010"/>
==Description== ''Tuctoria'' species have their spikelets spirally arranged on the axis; lemmas are entire (with a smooth, even margin) or denticulate (finely toothed), and often have a centrally placed short, sharp tip (mucro). The inflorescence is not cylindrical (as in ''Neostapfia''), and the spikelets are laterally flattened. The lemmas are narrower, the tip is mucronate or otherwise entire or denticulate. The caryopsis is not sticky, and the brown embryo is visible throughout the light-colored pericarp.<ref name="Reeder 1982"/>
==Species== There are three species in ''Tuctoria''. *''Tuctoria fragilis'' (originally described as ''Orcuttia fragilis'' by Jason Richard Swallen in 1944).<ref name="Swallen 1944"/> Found in Baja California (Mexico), it has culms up to {{convert|50|cm|in|abbr=on}} long, inflorescences often numbering several from the upper nodes, and a caryopsis that is somewhat pear-shaped and wrinkled.<ref name="Reeder 1982"/> *''Tuctoria greenei'' (originally ''Orcuttia grenei'' − Vasey).<ref name="Vasey 1891"/> Found in California, it has culms less than {{convert|20|cm|in|0|abbr=on}} long, with the inflorescence terminal on the flowering culm. The caryopsis is {{convert|2|mm|in|2|abbr=on}} long and oblong, and wrinkled.<ref name="Reeder 1982"/> *''Tuctoria mucronata'' (originally ''Orcuttia mucronata'' − Crampton).<ref name="Crampton 1959"/> Endemic to Solano County south of Dixon, Northern California. Its inflorescence is partially included in the upper lead, and its lemmas taper gradually to a mucronate tip. The caryopsis is smooth, measuring {{convert|3|mm|in|1|abbr=on}} long.<ref name="Reeder 1982"/>
==Ecology and distribution== [[File:Vernal Pools 2.jpg|thumb|right|Vernal pool in Sacramento Valley, central California]] ''Tuctoria'' species are endemic to seasonal pools in the southwestern US. Like all species in tribe Orcuttieae, the growth of ''Tuctoria'' species is initiated underwater. When pools dry, the plants undergo a metamorphosis whereby aquatic foliage is replaced with terrestrial foliage.<ref name="Keeley 1998"/> The terrestrial foliage has Kranz anatomy, indicating the use of C-4 photosynthesis. This adaptation help the plants survive the longs periods of drought-like conditions experienced when the pools dry.<ref name="Keeley 1998b"/> In years with little rainfall, their seed banks remain dormant until a season of rainfall that is adequate to fill the pool basins. In ''T. greenei'', germination is almost entirely dependent upon a combination of anaerobic conditions and light. This strategy helps the plant begin germination when pool basins are filled with water. In years of low precipitation, the soil subsurface is likely to be anaerobic or hypoxic, and inhibit germination.<ref name="Keeley 1988"/>
''Tuctoria greenei'' is of high conservation concern in California, as vernal pool systems are in decline due to agricultural development and urban expansion.<ref name="Gordon 2012"/>
==See also== *List of ''Poaceae'' genera
==References==
{{Reflist|colwidth=30em|refs=
<ref name="Boykin 2010">{{cite journal |author1=Boykin, Laura M. |author2=Kubatko, Laura Salter |author3=Lowrey, Timothy K. |title=Comparison of methods for rooting phylogenetic trees: A case study using Orcuttieae (Poaceae: Chloridoideae) |journal=Molecular Phylogenetics and Evolution |year=2010 |volume=54 |issue=3 |pages=687–700 |doi=10.1016/j.ympev.2009.11.016 |pmid=19931622|bibcode=2010MolPE..54..687B }}</ref>
<ref name="Crampton 1959">{{cite journal |author=Crampton, B. |title=The grass genera ''Orcuttia'' and ''Neostapfia'': a study in habitat and morphological specialization |year=1959 |journal=Madroño |volume=15 |issue=4 |pages=97–110 |jstor=41422993 }}</ref>
<ref name="Gordon 2012">{{cite journal |author1=Gordon, Sarah P. |author2=Sloop, Christina M. |author3=Davis, Heather G. |author4=Cushman, J. Hall |title=Population genetic diversity and structure of two rare vernal pool grasses in central California |journal=Conservation Genetics |year=2012 |volume=13 |issue=1 |pages=117–130 |doi= 10.1007/s10592-011-0269-y |bibcode=2012ConG...13..117G |url=http://www.sonoma.edu/users/c/cushman/pdf/Gordon%20et%20al%202012.pdf }}</ref>
<ref name="Keeley 1988">{{cite journal |author=Keeley, Jon E. |title=Anaerobiosis as a stimulus to germination in two vernal pool grasses |journal=American Journal of Botany |year=1988 |volume=75 |issue=7 |pages=1086–1089 |jstor=2443777 |url=http://www.werc.usgs.gov/fileHandler.ashx?File=/Lists/Products/Attachments/967/Anaerobiosis%20as%20a%20stimulus%20to%20germination%20in%20two%20vernal%20poo.pdf |archive-url=https://web.archive.org/web/20160304133924/http://www.werc.usgs.gov/fileHandler.ashx?File=/Lists/Products/Attachments/967/Anaerobiosis%20as%20a%20stimulus%20to%20germination%20in%20two%20vernal%20poo.pdf |url-status=dead |archive-date=2016-03-04 |doi=10.2307/2443777}} (online pdf here: https://www.docdroid.net/LAenrBq/anaerobiosis-as-a-stimulus-to-germination-in-two-vernal-pool-grasses.pdf) </ref>
<ref name="Keeley 1998">{{cite journal |author=Keeley, J.E. |title=Diel acid fluctuations in C-4 amphibious grasses |journal=Photosynthetica |year=1988 |volume=35 |issue=2 |pages=273–277 |doi=10.1023/A:1006927327013 |url=http://www.werc.usgs.gov/OLDsitedata/seki/pdfs/k1998_diel%20acid%20fluctuations%20in%20c4%20amphibious%20grasses.pdf |archive-url=https://web.archive.org/web/20160304131702/http://www.werc.usgs.gov/OLDsitedata/seki/pdfs/k1998_diel%20acid%20fluctuations%20in%20c4%20amphibious%20grasses.pdf |url-status=dead |archive-date=2016-03-04 }}</ref>
<ref name="Keeley 1998b">{{cite journal |author=Keeley, Jon E. |title=C<sub>4</sub> photosynthetic modifications in the evolutionary transition from land to water in aquatic grasses |journal=Oecologia| year=1998 |volume=116 |issue=1/2 |pages=85–97 |jstor=4222061 |url=http://www.werc.usgs.gov/fileHandler.ashx?File=/Lists/Products/Attachments/934/K1998_C4%20photosynthetic%20Modifications%20in%20the%20Evolutionary.pdf |archive-url=https://web.archive.org/web/20140504001841/http://www.werc.usgs.gov/fileHandler.ashx?File=/Lists/Products/Attachments/934/K1998_C4%20photosynthetic%20Modifications%20in%20the%20Evolutionary.pdf |url-status=dead |archive-date=2014-05-04 |doi=10.1007/s004420050566 |pmid=28308544 |bibcode=1998Oecol.116...85K }} (online pdf here: https://www.docdroid.net/fsBkZsK/c4-photosynthetic-modifications-in-the-evolutionary-transition-from-land-to-water-in-aquatic-grasses.pdf) </ref>
<ref name="Reeder 1965">{{cite journal |author=Reeder, John R. |title=The tribe Orcuttieae and the subtribes of the Pappophoreae (Gramineae) |journal=Madroño |year=1965 |volume=18 |issue=1 |pages=18–28 |jstor= 41423175 }}</ref>
<ref name="Reeder 1982">{{cite journal |author=Reeder, John R. |title=Systematics of the tribe Orcuttieae (Gramineae) and the description of a new segregate genus, ''Tuctoria'' |journal=American Journal of Botany |year=1982 |volume=69 |issue=7 |pages=1082–95 |jstor=2443083 |doi=10.2307/2443083}}</ref>
<ref name="Swallen 1944">{{cite journal |author=Swallen, Jason R. |title=A new species of ''Orcuttia'' from Baja California |journal=Journal of the Washington Academy of Sciences |year=1944 |volume=34 |page=308 |url=https://www.biodiversitylibrary.org/page/39690081}}</ref>
<ref name="Vasey 1891">{{cite journal |author=Vasey, George |title=New grasses |journal=Botanical Gazette |year=1891 |volume=16 |issue=5 |pages=145–147 |jstor=2993784 |doi=10.1086/326655|url=https://www.biodiversitylibrary.org/part/222043 }} {{open access}}</ref>
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==External links== *[http://www.kew.org/data/grasses-db/www/gen00669.htm Grassbase - The World Online Grass Flora]
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Category:Chloridoideae Category:Bunchgrasses of North America Category:Native grasses of California Category:Grasses of Mexico Category:Poaceae genera