Malvaceae, or the mallows, is a family of flowering plants estimated to contain 244 genera with 4225 known species. Well-known members of economic importance include okra, cotton, cacao and durian. There are also some genera containing familiar ornamentals, such as Alcea (hollyhock), Malva (mallow), and Tilia (lime or linden tree). The largest genera in terms of number of species include Hibiscus (300 species), Sterculia (250 species), Dombeya (250 species), Pavonia (200 species) and Sida (200 species). Taxonomy and nomenclature The circumscription of the Malvaceae is controversial. The traditional Malvaceae sensu stricto comprise a very homogeneous and cladistically monophyletic group. Another major circumscription, Malvaceae sensu lato, has been more recently defined on the basis that genetics studies have shown the commonly recognised families Bombacaceae, Tiliaceae, and Sterculiaceae, which have always been considered closely allied to Malvaceae s.s., are not monophyletic groups. Thus, the Malvaceae can be expanded to include all of these families so as to compose a monophyletic group. Adopting this circumscription, the Malvaceae incorporate a much larger number of genera. Subfamilies This article is based on the second circumscription, as presented by the Angiosperm Phylogeny Website. The Malvaceae s.l. (hereafter simply "Malvaceae") comprise nine subfamilies. A tentative cladogram of the family is shown below. The diamond denotes a poorly supported branching (<80%). Until recently, relationships between these subfamilies were either poorly supported or almost completely obscure. Continuing disagreements focused primarily on the correct circumscription of these subfamilies, including the preservation of the family Bombacaceae. A study published in 2021 presented a fully resolved phylogenetic framework for Malvaceae s.l. using genomic data for all nine subfamilies. Regarding the traditional Malvaceae s.s., the subfamily Malvoideae approximately corresponds to that group. Synapomorphies The relationships between the "core Malvales" families used to be defined on the basis of shared "malvean affinities". These included the presence of malvoid teeth, stems with mucilage canals, and stratified wedge-shaped phloem. These affinities were problematic because they were not always shared within the core families. Later studies revealed more unambiguous synapomorphies within Malvaceae s.l.. Synapomorphies identified within Malvaceae s.l. include the presence of tile cells, trichomatous nectaries, and an inflorescence structure called a bicolor unit. Tile cells consist of vertically positioned cells interspersed between and dimensionally similar to procumbent ray cells. Evidence of Malvean wood fossils has confirmed their evolutionary link in Malvaceae s.l., as well as explained their diverse structures. Flowers of Malvaceae s.l. exhibit nectaries consisting