Convolvulus

Accepted name/Authority/Place of publication:

Convolvulus L. Sp. Pl. 1: 153 (1753)

Tribe:

CONVOLVULEAE

Synonyms:

Rhodorhiza Webb in Bot. Reg.. Misc. 69 (1841)

Type Species:

Convolvulus arvensis L.

Habit:

Annual or perennial, erect, prostrate or climbing herbs, sometimes lignified at the base, woody lianas and erect shrubs, the latter sometimes spiny. Pubescent or not, the hairs unbranched.

Leaves:

Sessile or petiolate, margins entire to deeply lobed, sometimes highly variable in shape within an individual or a species.

Inflorescences:

Axillary or terminal; flowers in one to many-flowered cymes, rarely arranged in a compound thyrsi, sometimes apparently solitary axillary. Bracteoles usually small and filiform but in compact inflorescences sometimes leafy, ovate or lanceolate.

Flowers:

Sepals 5, quincuncial, usually unequal, the middle sepal often asymmetric, the exposed half resembling the outer sepals and the enclosed half resembling the inner sepals. Corolla funnel-form or rarely campanulate; margin entire or lobed, rarely ±fimbriate; limb pink, white, purple, blue or rarely yellow, the centre often differently coloured, the throat occasionally with dark marks; usually glabrous except for the midpetaline bands that are pubescent in the upper half in most species. Stamens included, often unequal. Filaments dilated at the base, filiform above, glabrous or with sessile or stalked glands in the dilated part. Anthers +/- equal, oblong to sagitate, rarely broadly oblong, dehiscing longitudinally. Ovary ovoid, conical or globular, entire or lobed, glabrous or hairy, sometimes densely so. Style one, slender, glabrous or hairy. Stigmas two, filiform or cylindrical.

Pollen:

Elliposidal, trciolpate.

Fruits:

Capsules dehiscing loculicidally or irregularly.

Seeds:

1-4, surface smooth, tuberculate, ridged or hairy.

Distribution:

The genus is essentially temperate in its distribution. The most important centres of diversity are to be found in the Mediterranean (including Macaronesia), East Africa, Central Asia and Arabia. Southern Africa, temperate south America and Australasia also harbour significant numbers of species. There are only three species in north America although Calystegia, that constitutes a monophyletic group nested within Convolvulus, is diverse there. Convolvulus arvensis is a widely distributed weed species.

Number of Species:

200

Infrageneric Characters:

Carine et al (2004) identified two major groupings within
the genus. The first comprises perennial, mostly erect plants which have
sessile, always entire leaves. Chromosome numbers for this group are 30, 36 and
60. The second clade includes Calystegia and comprises species that have
distinctly petiolate leaves that are sometimes divided. The habit is variable
but typically, trailing or climbing. Chromosome numbers reported for this clade
are 20, 22, 24, and 28 (or multiples thereof). A project is currently underway
to expand the sampling of Carine et al (2004) more widely across the genus to
better understand morphological evolution and the classification of the genus.

References:

Carine, M. A., Francisco-Ortega, J., Santos-Guerra, A. and Russell. S. J. (2004). Relationships of island and continental floras: molecular evidence for multiple colonisations into Macaronesia and subsequent back-colonisation of the continent in Convolvulus L. American Journal of Botany 91: 1070-1085.

Sa’ad, F. 1967. The Convolvulus species of the Canary Islands, the Mediterranean region and the near and Middle East. Medelingen van het Botanisch Museum en Herbarium van de Rijksuniversiteit te Utrecht 281: 1–288.