{{Short description|Genus of flowering plants in the rock rose family Cistaceae}} {{Automatic taxobox | image = Crocanthemum georgianum.jpg | image_caption = ''Crocanthemum georgianum'' | taxon = Crocanthemum | authority = Spach (1836) | subdivision_ranks = Species | subdivision = 20, see text | subdivision_ref = <ref name = Kew/> | synonyms = *''Heteromeris'' {{small|Spach (1836)}} *''Trichasterophyllum'' {{small|Willd. ex Link (1820)}} |synonyms_ref = <ref name = Kew/> }}
'''''Crocanthemum''''' is a genus of flowering plants in the family Cistaceae.<ref name=Kew/> They are native to both North and South America where they are widespread.<ref name=fna/> The common name '''frostweed''' relates to the ice crystals which form from sap exuding from cracks near the base of the stem in the late fall.<ref>{{cite book|author1=Niering, William A.|author2=Olmstead, Nancy C.|title=The Audubon Society Field Guide to North American Wildflowers - Eastern Region|isbn=0-394-50432-1|publisher=Alfred A. Knopf, New York|year=1979|page=467}}</ref>
''Crocanthemum'' are herbaceous perennials or subshrubs with alternate leaves. With the exception of species in California, they generally produce two types of flowers: showy, yellow chasmogamous (cross-pollinated) produced earlier in the growing season, followed by cleistogamous (self-pollinated) flowers that are smaller and lack petals.<ref name=fna/><ref name=Weakley/> All species of ''Crocanthemum'' are fire tolerant and are found in open habitats.
Although the genus was first named in 1836 to encompass New World species of ''Helianthemum'', it generally went unrecognized by taxonomists and its species were included in a broad concept of ''Helianthemum'' throughout much of the 1800s and 1900s. However, phylogenetic studies in 2004 and 2009 indicated that the New World species of ''Helianthemum'' were more closely related to ''Hudsonia'' than Old World ''Helianthemum''.<ref name=fna/><ref name=Guzman/> This required the resurrection of the genus ''Crocanthemum'' in order to maintain monophyly.
==Species== 20 species are accepted.<ref name = Kew/> * ''Crocanthemum aldersonii'' {{small|(Greene) Janch.}} * ''Crocanthemum arenicola'' {{small|(Chapm.) Barnhart}} * ''Crocanthemum argenteum'' {{small|(Hemsl.) Janch.}} * ''Crocanthemum bicknellii'' {{small|(Fernald) Janch.}} * ''Crocanthemum brasiliense'' {{small|(Lam.) Spach}} * ''Crocanthemum canadense'' {{small|(L.) Britton}} * ''Crocanthemum carolinianum'' {{small|(Walter) Spach}} * ''Crocanthemum corymbosum'' {{small|(Michx.) Britton}} * ''Crocanthemum dumosum'' {{small|E.P.Bicknell}} * ''Crocanthemum georgianum'' {{small|(Chapm.) Barnhart}} * ''Crocanthemum glomeratum'' {{small|(Lag.) Janch.}} * ''Crocanthemum greenei'' {{small|(B.L.Rob.) Sorrie}} * ''Crocanthemum nashii'' {{small|(Britton) Barnhart}} * ''Crocanthemum nutans'' {{small|(Brandegee) Janch.}} * ''Crocanthemum pringlei'' {{small|(S.Watson) Janch.}} * ''Crocanthemum propinquum'' {{small|(E.P.Bicknell) E.P.Bicknell}} * ''Crocanthemum rosmarinifolium'' {{small|(Pursh) Janch.}} * ''Crocanthemum scoparium'' {{small|(Nutt.) Millsp.}} * ''Crocanthemum suffrutescens'' {{small|(B.Schreib.) Sorrie}}
==References== {{Reflist|refs= <ref name=fna>[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=108390 ''Crocanthemum''] Flora of North America</ref> <ref name=Guzman>{{cite journal |last1=Guzman |first1=Beatriz |last2=Vargas |first2=Pablo |date=21 January 2009 |title=Historical biogeography and character evolution of Cistaceae (Malvales) based on analysis of plastid ''rbcL'' and ''trnL-trnF'' sequences |url=http://www.rjb.csic.es/jardinbotanico/ficheros/documentos/pdf/pubinv/PVG/GuzmanVargas_009ODECistaceae.pdf |journal=Organisms Diversity & Evolution |volume=9 |issue=2 |pages=83–99 |doi=10.1016/j.ode.2009.01.001 |bibcode=2009ODivE...9...83G |access-date=2019-12-11 }}</ref> <ref name=Kew>{{cite web |title=''Crocanthemum'' Spach |url=https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:30016913-2 |website= Plants of the World Online |publisher=Royal Botanical Gardens, Kew |access-date=19 September 2024}}</ref> <ref name=Weakley>{{cite web |url=http://www.herbarium.unc.edu/flora.htm |title= Flora of the Southern and Mid-Atlantic States |author= Alan Weakley |date= 2015}}</ref> }}
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Category:Cistaceae Category:Malvales genera Category:Flora of the Americas Category:Taxa described in 1836 Category:Taxa named by Édouard Spach