font settings and languages

Font Size: Large | Normal | Small
Font Face: Verdana | Geneva | Georgia
Languages:

Urena trilobata

Interesting Facts

[ Back to top ]
 

Description

[ Back to top ]

Family Malvaceae

Herbs, shrubs , or less often trees ; indumentum usually with peltate scales or stellate hairs . Leaves alternate, stipulate , petiolate ; leaf blade usually palmately veined, entire or various lobed . Flowers solitary, less often in small cymes or clusters , axillary or subterminal , often aggregated into terminal racemes or panicles, usually conspicuous , actinomorphic , usually bisexual (unisexual in Kydia) . Epicalyx often present, forming an involucre around calyx, 3- to many lobed. Sepals 5, valvate , free or connate . Petals 5, free, contorted, or imbricate, basally adnate to base of filament tube . Stamens usually very many, filaments connate into tube; anthers 1-celled. Pollen spiny . Ovary superior, with 2-25 carpels, often separating from one another and from axis; ovules 1 to many per locule; style as many or 2 × as many as pistils, apex branched or capitate. Fruit a loculicidal capsule or a schizocarp, separating into individual mericarps, rarely berrylike when mature (Malvaviscus) ; carpels sometimes with an endoglossum (a crosswise projection from back wall of carpel to make it almost completely septate . Seeds often reniform , glabrous or hairy , sometimes conspicuously so.

About 100 genera and ca. 1000 species: tropical and temperate regions of N and S Hemisphere; 19 genera (four introduced ) and 81 species (24 endemic, 16 introduced) in China.

Molecular studies have shown that the members of the Bombacaceae, Malvaceae, Sterculiaceae, and Tiliaceae form a very well-defined monophyletic group that is divided into ten also rather well-defined clades, only two of which correspond to the traditional families Bombacaceae and Malvaceae. Some of the remaining groups are included entirely within either of the remaining families but others cut across the traditional divide between the Sterculiaceae and Tiliaceae. A majority of authors , most notably Bayer and Kubitzki (Fam. Gen. Vasc. Pl. 5: 225-311. 2003), has favored including everything within a greatly enlarged Malvaceae, and treating the individual clades as subfamilies. The alternative view is that the individual clades should be treated as a series of ten families: Bombacaceae (Bombacoideae), Brownlowiaceae (Brownlowioideae), Byttneriaceae (Byttnerioideae), Durionaceae (Durionoideae), Helicteraceae (Helicteroideae), Malvaceae (Malvoideae), Pentapetaceae (Dombeyoideae), Sparrmanniaceae (Grewioideae), Sterculiaceae (Sterculioideae), and Tiliaceae (Tilioideae) (Cheek in Heywood et al. , Fl. Pl. Fam. World. 201-202. 2007) . For the present treatment, we prefer to retain the familiar, traditional four families, so as to maintain continuity with the treatments in FRPS, and to await a consensus on the two alternative strategies for dealing with the very widely accepted clades.

The traditional Malvaceae coincides exactly with one of the major clades. The only possible problem is the relationship with the Bombacaceae, which also has primarily 1-loculed anthers, and some authorities have suggested that the Bombacaceae should be included within the Malvaceae.

Members of the Malvaceae are important as fiber crops (particularly cotton, Gossypium) . Young leaves of many species can be used as vegetables, and species of Abelmoschus and Hibiscus are grown as minor food crops. Many species have attractive flowers and an ever-increasing selection is grown as ornamentals . Several have been cultivated for a very long time, particularly species of Hibiscus, and some of these are not known in the wild.[1]

Genus Urena

Herbs perennial or shrubs , stellate . Leaves alternate; leaf blade orbicular or ovate , palmately lobed or sinuate , with 1 or more prominent foliar nectaries on abaxial surface. Flowers solitary or nearly fascicled, rarely racemelike, axillary or rarely aggregated on twig tips . Epicalyx campanulate , 5-lobed. Calyx 5-parted. Petals 5, stellate puberulent abaxially. Staminal column truncate or slightly incised; anthers numerous , on outside of staminal column only, nearly sessile. Ovary 5-loculed; ovule 1 per locule; style branches 10, reflexed ; stigma discoid , apically ciliate . Fruit a schizocarp, subglobose; mericarps 5, ovoid , usually with spines, these each with a cluster of short barbs at tips. Seed 1, obovoid-trigonous or reniform , glabrous .

About six species: in tropical and subtropical regions; three species (one endemic) in China.

Some authorities have restricted Urena to the taxa with barb-tipped setae, sometimes treating these as a single, very variable, pantropical species, and placed other species, including U. repanda, in Pavonia. Some species of Triumfetta (Tiliaceae s.l.) are superficially rather similar and have been confused with this genus.[2]

Taxonomy

[ Back to top ]

Similar Species

[ Back to top ]

Members of the genus Urena

ZipcodeZoo has pages for 4 species, subspecies, varieties, forms, and cultivars in this genus:

U. capitata (Malva De Caballo) · U. lobata (Aramina) · U. lobata var. vertomensosa (Caesar-Weed) · U. sinuata (Burrmallow)

More Info

[ Back to top ]

Further Reading

[ Back to top ]

Notes

[ Back to top ]

Contributors

Identifiers

Footnotes

  1. Ya Tang, Michael G. Gilbert & Laurence J. Dorr "Malvaceae". in Flora of China Vol. 12 Page 240, 264,299, 302. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
  2. "Urena". in Flora of China Vol. 12 Page 265, 280,286. Published by Science Press (Beijing) and Missouri Botanical Garden Press. Online at EFloras.org. [back]
Last Revised: 2012-07-28