Althaea is a genus within the family Malvaceae, which also includes, inter alia, Abutilon, Alcea, Gossypium, Hibiscus, Malva and Sidalcea, and is particularly close to Alcea and Kitaibelia.
Species of Althaea are annual or perennial herbs, and are known vernacularly as marshmallows. They have a broad distribution in the western Palaeoarctic, being found in North Africa, Mediterranean Europe, France, Britain, the Balkans, south west and central Asia and southern Russia, but are absent from more northerly latitudes. One species, Althaea ludwigii, is also found in arid regions further south in Africa, including Namibia.
The Common Marshmallow, Althaea officinalis, was used in medicine and in confectionary.
Althaea is a genus of the tribe Malveae and sub-tribe Malvinae of the family Malvaceae. It is particularly close to the Hollyhocks, genus Alcea. Alcea has often been considered as a section in Althaea and most species of Alcea have been assigned to Althaea at various times.
There are currently 5 or 6 species and one interspecific hybrid placed in the genus. It is widely stated that there are 12 species in the genus, but I have been unable to identify the additional species, and suspect that they are species latterly transferred to Alcea.
The species are divided into 2 sections. Section Althaea contains the perennial species, A. officinalis (Common Marshmallow) and A. cannabina (Hemp-leaved Marshmallow), and intermediate forms. Section Hirsutae contains the annual species A. hirsuta (Hairy Marshmallow), A. longiflora and A. ludwigii. A. hirsuta hybridises with Malva aegyptia to form ×Malvalthaea transcaucasica, from which fact we may suspect that section Hirsutae is misplaced in Althaea, or Malva aegyptia and its allies are misplaced in Malva. Recent DNA sequence data (see discussion of the Malva alliance) indicates that the former is the case.
It is likely that a number of sterile hybrid mallows usually sold as Malva are in fact hybrids between Alcea and Althaea.
The genus is named from the Greek althaia, to cure, which is an allusion to the medicinal properties of some species.
Althaea officinalis has a chromosome count of 42, or thereabouts; Althaea cannabina is tetraploid, with a count of 84. Althaea hirsuta has 42 chromosomes.
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© 2004, 2005, 2006 Stewart Robert Hinsley