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. Another species, Althaea australis, has recently been described from South Australia.
The Common Marshmallow, Althaea officinalis, was used in medicine and in confectionary.
The genus is named from the Greek αλθαια (althaia), to cure, which is an allusion to the medicinal properties of some species.
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 is considerable disagreement on the classification of the genus. It is widely stated that there are 12 species in the genus, but I have been unable to identify that many species, and suspect that the count includes species latterly transferred to Alcea. I recognise 7 species and one interspecific hybrid, but some sources recognise an additional species (Althaea broussonetiifolia, a segregate of Althaea armeniaca), and others combine some of the species.
The species are divided into 2 sections. Section Althaea contains the perennial species, Althaea officinalis (Common Marshmallow) and Althaea cannabina (Hemp-leaved Marshmallow), and intermediate forms, including Althaea armeniaca. Section Hirsutae contains the annual species Althaea australis, Althaea hirsuta (Hairy Marshmallow), A. longiflora and A. ludwigii. A. hirsuta is believed to have hybridised 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.
A number of sterile hybrid mallows usually sold as Malva are in fact hybrids (×Alcalthaea) between Alcea and Althaea.
Marshmallows are usually propagated from seed. However some cultivars do not come true from seed, and seed of the hybrid Althaea ×taurinensis may be difficult to obtain. The perennial species can also be propagated by cuttings, or by division.
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, 2008 Stewart Robert Hinsley