Definitions

loculicidal

Malvaceae

Malvaceae, or the mallow family, is a family of flowering plants containing over 200 genera with close to 2,300 species. The largest genera in terms of number of species include Hibiscus (300 species), Sterculia (250 species), Dombeya (225 species), Pavonia (200 species) and Sida (200 species).

Taxonomy

The circumscription of the Malvaceae is very controversial. The traditional Malvaceae sensu stricto comprises a very homogeneous and cladistically monophyletic group. Another major circumscription, Malvaceae sensu lato, has been more recently defined on the basis that newer techniques have shown that the commonly recognised families Bombacaceae, Tiliaceae, and Sterculiaceae, which have always been considered very close to Malvaceae s.s., are not monophyletic groups. Thus the Malvaceae have been expanded to include all of these families so to have a monophyletic group. Adopting this circumscription, Malvaceae incorporates a much larger number of genera.

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%).

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It is important to point out the relationships between these subfamilies are still either poorly supported or almost completely obscure, so that the very definition of the family may change dramatically as new studies are published.

If looking for information about the traditional Malvaceae s.s., we recommend referring to Malvoideae, the subfamily that approximately corresponds to that group.

Description

Most species are herbs or shrubs but some are trees and lianas.

Leaves and stems

Leaves are generally alternate, often palmately lobed or compound and palmately veined. The margin may be entire, but when dentate a vein ends at the tip of each tooth (malvoid teeth). Stipules are present. The stems contain mucous canals and often also mucous cavities. Hairs are common, and are most typically stellate.

Flowers

The flowers are commonly borne in definite or indefinite axillary inflorescences, which are often reduced to a single flower, but may also be cauliflorous, oppositifolious or terminal. They often bear supernumerary bracts. They can be unisexual or bisexual and are generally actinomorphic, often associated with conspicuous bracts, forming an epicalyx. They generally have five valvate sepals, most frequently basally connate. Five imbricate petals. The stamens are five to numerous, connate at least at their bases, but often forming a tube around the pistils. The pistils are composed of two to many connate carpels. The ovary is superior, with axial placentation. Capitate or lobed stigma. The flowers have nectaries made of many tightly packed glandular hairs, usually positioned on the sepals.

Fruits

Most often a loculicidal capsule, a schizocarp or nut.

Uses

A number are pest species in agriculture, including Abutilon theophrasti and Modiola caroliniana plus others that are garden escapes. Cotton (4 species of Gossypium), kenaf (Hibiscus cannabinus) and okra (Abelmoschus esculentus) are important agricultural crops.

References

  • Baum, D. A., W. S. Alverson, and R. Nyffeler (1998). "A durian by any other name: taxonomy and nomenclature of the core Malvales". Harvard Papers in Botany 3 315–330.
  • Baum, D. A., S. D. Smith2, A. Yen, W. S. Alverson, R. Nyffeler, B. A. Whitlock and R. L. Oldham (2004). "Phylogenetic relationships of Malvatheca (Bombacoideae and Malvoideae; Malvaceae sensu lato) as inferred from plastid DNA sequences". American Journal of Botany 91 1863–1871. (abstract online here).
  • Bayer, C., J. R. Hoppe, K. Kubitzki, M. F. Fay, A. Y. De Bruijn, V. Savolainen, C. M. Morton, K. Kubitzki, W. S. Alverson, and M. W. Chase (1999). "Support for an expanded family concept of Malvaceae within a recircumscribed order Malvales: a combined analysis of plastid atpB and rbcL DNA sequences". Botanical Journal of the Linnean Society 129 267–303.
  • Bayer, C. and K. Kubitzki 2003. Malvaceae, pp. 225-311. In K. Kubitzki (ed.), The Families and Genera of Vascular Plants, vol. 5, Malvales, Capparales and non-betalain Caryophyllales.
  • Edlin, H. L. (1935). "A critical revision of certain taxonomic groups of the Malvales". New Phytologist 34 (1-20): 122–143.
  • Judd, W. S., and S. R. Manchester (1997). "Circumscription of Malvaceae (Malvales) as determined by a preliminary cladistic analysis of morphological, anatomical, palynological, and chemical characters". Brittonia 49 384–405.
  • Judd, W. S., C. S. Campbell, E. A. Kellogg and P. F. Stevens. Plant Systematics: A Phylogenetic Approach.
  • Maas, P. J. M. and L. Y. Th. Westra. 2005. Neotropical Plant Families (3rd edition).
  • Perveen, A., E. Grafström and G. El-Ghazaly (2004). "World Pollen and Spore Flora 23. Malvaceae Adams. P.p. Subfamilies: Grewioideae, Tilioideae, Brownlowioideae". Grana 43 129–155. (abstract online here).
  • Tate, J. A., J. F. Aguilar, S. J. Wagstaff, J. C. La Duke5, T. A. Bodo Slotta and B. B. Simpson (2005). "Phylogenetic relationships within the tribe Malveae (Malvaceae, subfamily Malvoideae) as inferred from ITS sequence data". American Journal of Botany 92 584–602. (abstract online here).

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