''Xylothamia'', the desert goldenrods, is a formerly accepted genus of

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...

s in the family

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

. Until 2003, it was held to contain nine species of shrubs native to the deserts of Mexico and the southwestern United States. , Plants of the World Online divided the nine former species of ''Xylothamia'' among '' Aquilula'', '' Gundlachia'', and ''

Medranoa ''Medranoa'' is a genus of flowering plant in the family Asteraceae, native to northeastern Mexico and Texas. The genus was established in 2004, initially with a single species. It was expanded to five species in 2007, incorporating species form ...

''.

Taxonomy

The genus ''Xylothamia'' was first described in 1990 with nine species.

Molecular phylogenetic Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...

studies subsequently showed that these fell into two

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

s. Four species, including the

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

of ''Xylothamia'', were most closely related to the Caribbean genus '' Gundlachia'', and were transferred to that genus by Lowell E. Urbatsch and Roland P. Roberts in 2004. ,

Plants of the World Online Plants of the World Online (POWO) is an online taxonomic database published by the Royal Botanic Gardens, Kew. History Following the Convention on Biological Diversity, the Royal Botanic Gardens in Kew launched Plants of the World Online i ...

accepted the transfer, and treated ''Xylothamia'' as a

synonym A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...

of ''Gundlachia''. Urbatsch and Roberts divided the remaining five species between four genera, ''Neonesomia'' with two species, and ''Chihuahuana'', ''Medranoa'', and ''Xylovirgata'' with one species each. In 2007, Guy L. Nesom considered that four separate genera were not justified, even though there were morphological differences among them, and placed all five species in ''

''. Nesom later transferred one of the species placed in ''Gundlachia'', ''Gundlachia riskindii'', to the

monotypic In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...

genus '' Aquilula''. , Plants of the World Online accepted these placements, dividing the nine former species of ''Xylothamia'' among ''Aquilula'', ''Gundlachia'', and ''Medranoa''. All nine species belong in the subtribe Solidagininae.

Species

, Plants of the World Online divided the nine former species of ''Xylothamia'' among ''Aquilula'', ''Gundlachia'', and ''Medranoa''. Species accepted in '' Aquilula'': *''Xylothamia riskindii'' (B.L.Turner & G.Langford) G.L.Nesom = '' Aquilula riskindii'' Species accepted in '' Gundlachia'': *''Xylothamia diffusa'' Benth.) G.L.Nesom = '' Gundlachia diffusa'' *''Xylothamia triantha'' (S.F.Blake) G.L.Nesom = ''

Gundlachia triantha ''Gundlachia triantha'', the TransPecos goldenshrub or Trans-Pecos desert goldenrod, is a North American species of plants in the sunflower family. It is native to northern Mexico ( Chihuahua, Coahuila, Durango, Nuevo León), with the range exte ...

'' *''Xylothamia truncata'' G.L.Nesom = '' Gundlachia truncata'' Species accepted in ''

'': *''Xylothamia johnstonii'' G.L.Nesom = ''

Medranoa johnstonii ''Medranoa'' is a genus of flowering plant in the family Asteraceae, native to northeastern Mexico and Texas. The genus was established in 2004, initially with a single species. It was expanded to five species in 2007, incorporating species form ...

*''Xylothamia palmeri'' (A.Gray) G.L.Nesom = ''

Medranoa palmeri ''Medranoa'' is a genus of flowering plant in the family Asteraceae, native to northeastern Mexico and Texas. The genus was established in 2004, initially with a single species. It was expanded to five species in 2007, incorporating species form ...

'' *''Xylothamia parrasana'' (S.F.Blake) G.L.Nesom = ''

Medranoa parrasana ''Medranoa'' is a genus of flowering plant in the family Asteraceae, native to northeastern Mexico and Texas. The genus was established in 2004, initially with a single species. It was expanded to five species in 2007, incorporating species form ...

'' *''Xylothamia pseudobaccharis'' (S.F.Blake) G.L.Nesom = ''

Medranoa pseudobaccharis ''Medranoa'' is a genus of flowering plant in the family Asteraceae, native to northeastern Mexico and Texas. The genus was established in 2004, initially with a single species. It was expanded to five species in 2007, incorporating species form ...

'' *''Xylothamia purpusii'' (Brandegee) G.L.Nesom = ''

Medranoa purpusii ''Medranoa'' is a genus of flowering plant in the family Asteraceae, native to northeastern Mexico and Texas. The genus was established in 2004, initially with a single species. It was expanded to five species in 2007, incorporating species form ...

References

Astereae Asteraceae genera Historically recognized angiosperm genera {{Astereae-stub