Senecio inaequidens

Name and classification

Senecio inaequidens DC.
Family Asteraceae, Tribe Senecioneae

Common names

South African ragwort

Disseminule

fruit

Description

Fruit an achene, narrowly cylindrical, straight to somewhat curved, (1.5)2.0–2.5(2.8) mm long, 0.3–0.5 mm in diameter; cross-section terete to unequally 4-sided; surface green when young, dark reddish-brown at maturity, thickly pubescent in several (ca. 9) rows along the length of the fruit. Scar basal, cup-shaped. Pappus white, 2–3 times as long as achene, easily deciduous, often absent, leaving a white apical collar. Style base white, sometimes protruding beyond the apical collar. Embryo straight, spatulate; endosperm absent.

Identification considerations

Fruits of various species of this genus look similar and may not be identifiable to species. Outside of its native distribution, Senecio inaequidens is most likely to be confused with the closely related invasive weed, S. madagascariensis, or the widespread species, S. vulgaris. Based on the limited numbers of achenes that were examined, S. inaequidens has the thickest rows of pubescence along the length of its fruit and the longest trichomes, S. madagascariensis has the sparsest rows and shortest trichomes, and S. vulgaris is intermediate for these characters.

Similar species

Senecio madagascariensis Poir.

Senecio vulgaris L. (non-FNW)

Distribution

native to southern Africa

became widely naturalized in Europe after its intriduction via wool imported from South Africa in the late 1800s; a declared pest plant in Australia, Mexico, and Hawaii, United States

Habitat

This temperate species has a wide range of ecological tolerances, ranging from dry to humid habitats, from stone to clay soils, and from sunny to shady locations. It occurs in natural forests, grasslands, scrub, rocky outcrops, sand dunes and a variety of ruderal areas.

General information

Senecio inaequidens is a short-lived (5–10 years) perennial herbaceous or woody shrub up to 100 cm tall. It can reproduce vegetatively, but mostly spreads via the wind-dispersal of its fruits. Possible methods of international dispersal include attachment to the surface of seafreight containers or railway cars or in the tire treads of road vehicles. Some scientists believe that S. inaequidens and S. madagascariensis are the same species; others consider them as part of the S. inaequidens complex, which includes both diploid and tetraploid populations.

achenes without pappus

achenes without pappus

achenes without pappus

achenes without pappus

achenes with pappus; photo: © P. Busselen, Katholiekd Universiteit Leuven(www.kuleuven-kortrijk.be/bioweb)

achenes with pappus; photo: © P. Busselen, Katholiekd Universiteit Leuven(www.kuleuven-kortrijk.be/bioweb)

achene surface, detail

achene surface, detail

apex showing stylar remains

apex showing stylar remains

apex showing stylar scar

apex showing stylar scar