Malvaceae Info (Home)
Composition | Division
Malvatheca (also known as Malbombina) is a clade roughly corresponding to the traditional Bombacaceae and Malvaceae, with some modification of content. The clade has been variously classified as a single family (Malvaceae), as two families (Bombacaceae and Malvaceae), as one family (Malvaceae) and part of a second (Sterculiaceae), as two subfamilies as in a broadly drawn Malvaceae (Malvoideae and Bombacoideae), and as elements of a single family (Malvaceae sensu Thorne).
Elements of the two families have also been granted familial rank by some authors, under the names Hibiscaceae, Fugosiaceae, Chiranthodendraceae, Fremontiaceae, Philippodendraceae and Plagianthaceae. The last two names represent the same or very similar concepts, Philippodendron being a synonym of Plagianthus. I have not seen a definition of the contents of Fremontiaceae, but it seems likely that it is equivalent to Chiranthodendraceae.
Several taxa have been classified in either family, by various authors, up to and including all genera in which the fruit is a capsule (Hibisceae and Gossypieae) . Other elements sometimes placed in Bombacaceae are Kydia and allies, Camptostemon, Lagunaria, Gossypieae (cottons and allies) (independently of Hibisceae), and Hampea (independently of the remainder of Gossypieae).
The unity of Malvatheca is supported by ITS (nrDNA), ndhF (cpDNA) and trnK/matK (cpDNA), but not rbcL (cpDNA) and atpB (cpDNA) sequence evidence. Morphologically the clade is defined by the presence of monothecate, bisporangiate, anthers (which may be homologous to half-anthers in other plants), but there are some ambiguities with this diagnosis.
Bombacaceae was originally classified as a tribe, Bombaceae, in Malvaceae. It has since been separated out, and is usually split into 3 tribes, Adansonieae (boababs, kapok, and allies), Matisieae and Durioneae (durians and allies). Reveal refers to a tribe Ochromeae (including Matisieae).
ITS and ndhF sequence data indicate that the Durioneae do not belong with the remainder of the traditional Bombacaceae. The bulk of this tribe (Neesia, Cullenia, Coelostegia, Boschia and Durio) forms a clade within Helicteroideae; Camptostemon belongs to Malvaceae sensu strictu; and Maxwellia is an aberrant member of the Lasiopetaleae (Byttnerioideae).
The Malvaceae sensu strictu is, and has been, divided into a number of tribes (typically 5, but rarely the same 5). The tribal concepts that I have encountered are
The names Philippodendreae, Plagiantheae and Sideae have also been used. These predate the regularisation of taxonomic suffixes. The first appears to represent a family, the second a sub-tribe, and the last has been used at the rank of sub-family and sub-tribe (at least).
The tribe Fremontodendreae, consisting of the 2 genera Fremontodendron and Chiranthodendron, which has usually been included within Sterculiaceae, but has sometimes been included with Bombacaceae, also belongs to Malvatheca.
A number of other genera, particularly Pentaplaris (ex Tiliaceae) and Uladendron (ex Sterculiaceae) also fall into Malvatheca.
In total Malvatheca has about 2150 species in about 140 genera.
The division of Malvatheca into subclades is unclear. The evidence currently available to me suggests an unresolved 5-way polytomy, but there are taxa for which I do not have data, which could mean that there are additional elements to this polytomy. The 5 elements of the polytomy are
A narrowly defined Ochromeae consisting of the Neotropical genera Ochroma (balsa) and Patinoa, but not the genera composing Matisieae. Further evidence may support the independence of Ochromeae, or place it in one of the other tribes (most likely Matisieae or Adansonieae). Ochroma is monotypic and Patinoa has 4 species.
Septotheca is monotypic. It does not clearly associated with any of the other groups, but in common with Ochroma and Patinoa its published DNA sequences are conservative, which might obscure relationships.
About 100 species, with a pantropical distribution, this tribe includes the baobabs (Adansonia), kapok (Bombax) and silk-cotton trees (Ceiba) and perhaps a dozen other genera.
A small Mesoamerican (California to Guatemala) tribe consisting of 3 or 4 species in 2 genera (Fremontodendron and Chiranthodendron).
Corresponding to Malvaceae sensu strictu, plus Matisieae, Pentaplaris, Camptostemon and Uladendron, this clade forms the main bulk of Malvatheca, with over 100 genera and 1000 species. It is divided into Matisieae, Pentaplaris, Uladendron, Radyera, Camptostemon, Lagunaria+Howittia, and a species rich clade, composed of Malveae, Gossypieae, Alyogyne and Hibisceae, which is given the name Eumalvoideae.
The Malvaceae Pages divides Malvoideae into 4 tribes - Matisieae, Hibisceae, Malveae and Gossypieae, leaving the genera Alyogyne, Camptostemon, Howittia and Lagunaria, Pentaplaris, Radyera and Uladendron unassigned (incertae sedis).
Matisieae is a small Neotropical tribe, consisting of the genera Matisia, Phragmotheca and Quararibea, which lack the echinate pollen of the remainder of Malvoideae. They are the sister group to the remainder (Core Malvoideae) of Malvoideae.
The genus Pentaplaris appears to be the sister group to the remainder of Core Malvoideae. The molecular sequence data is not unequivocal, but it is supported by Pentaplaris sharing the morphological traits of stalked monothecate anthers and echinate pollen with that clade. This implies that a tribe Pentaplarideae should be introduced to provide a home for this genus.
Malveae is a large and diverse grouping, with its centre of diversity in temperate and montane South America, but widely distributed in mediterranean and temperate regions throughout the world. It is one of only three groups within Malvaceae which has a predominantly temperate distribution, the others being Tilieae (Tilia and Craigia) and Lasiopetaleae. Malveae includes groups previously classified as Malveae sensu strictu, Abutileae, Sideae, Malopeae, Plagiantheae and Philippodendreae. Abutilieae and Sideae represent an identifiable division within Malveae, which may be named as sub-tribe Abutilinae. Plagianthus and allies (Hoheria, Lawrencia, Asterotrichion and Gynatrix) (Plagiantheae or Philippodendreae). together with Sidasodes and two species of Sida are the sister group to the rest of Abutilinae , and it may be worthwhile resurrecting Plagianthinae for this clade. Of the genera included in Malopeae, Malope and Kitaibelia are related to other European genera (Malva, Alcea and Althaea), whilst I Palaua is related to other South American members of Malveae, such as Tarasa or Nototriche .
Gossypieae is a moderately sized tribe of 7 genera and around 100 species. It is important in that it includes cotton (4 species of Gossypium), which is the world's pre-eminent fibre crop. The position of Gossypieae has been disputed in the past, it having been placed within Bombacaceae or within or near Hibisceae. ITS sequence data makes it relatively isolated, and most likely the sister group of Malveae. Morphologically it is diagnosed by seed characters and the presence of glands containing gossypols (anti-herbivore chemicals which act as a cardiac poison).
Kubitzki and Bayer  place Alyogyne as a anomalous genus in Gossypieae. It is not close to the remaining genera with Gossypieae, and I am unconvinced that it is closer to Gossypieae than to Malveae or Hibisceae. I would prefer to introduce a tribe Alyogyneae to hold this genus.
Hibisceae is another large and diverse grouping, predominantly tropical in distribution, but with some extensions into temperate regions. It is particularly diverse in Australia, but the greatest disparity is shown by the Afro-Madagascarian species. The fruit is usually a capsule, but this is an ancestral character shared with the other 4 divisions of Malvatheca. The schizocarpic-fruited genera traditionally placed in Malvavisceae (or Ureneae) are nested within Hibisceae, as are the 4 genera (Kydia, Nayariphyton, Julostylis and Dicellostyles) which Kubitzki and Bayer  separated as Kydieae .
The remaining genera, Uladendron, Radyera, Camptostemon, Howittia and Lagunaria, are basal lineages in Core Malvoideae. Howittia and Lagunaria are sister groups, but otherwise their relationships are unclear. Camptostemon may be the sister group to the Lagunaria/Howittia lineage. I suggest the introduction of tribes Uladendreae, Radyereae and Lagunarieae.
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© 2002, 2003, 2004, 2005, 2007 Stewart Robert Hinsley