T.E.R:R.A.I.N - Taranaki Educational Resource: Research, Analysis and Information Network

Senecio vulgaris (Groundsel)

Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Asterids
Order: Asterales
Family: Asteraceae
Tribe: Senecioneae
Genus: Senecio
Species: S. vulgaris
Binomial name: Senecio vulgaris
Synonyms: Senecio dunensis, Senecio radiatus
Common name: Groundsel, Common groundsel, Old-man-in-the-Spring, Grundy Swallow, Ground Glutton, Simson, Sention

Senecio vulgaris is small, upright annual weed in the daisy family Asteraceae. It is native to Europe and is now widely naturalised as a weed in suitable disturbed habitats worldwide.

Senecio vulgaris grow to about 20-40 cm tall, or smaller. Its terete, hollow stems often have fine longitudinal veins that are visible on the outside. Toward the base of the plant, these stems are often purplish green, becoming green above.
The leaves are alternate and are up to 60mm long and 25 mm wide. They are usually pinnatifid with a few blunt teeth along their margins in addition to the lobes. The terminal and lateral lobes are often truncated or notched, rather than tapered and pointed. The edges of the leaves margins curve downward (revolute). They are sparsely covered with soft, smooth, fine hairs. The plant has a shallow taproot.

The flower heads contain a number of open clusters of 10 to 22 small cylinder shaped, rayless, yellow flower heads (6 to 13 mm). There is a highly conspicuous ring of black tipped bracts at the base of the inflorescence, this is characteristic of many members of the genus Senecio. The flower heads usually only open once the seed is ripe. Senecio vulgaris generally produces about 2000 seeds per plant depending on growing conditions. The seeds are easily spread by wind because of the pappus being attached to the seeds. 
Unlike most plants; there can be more than one generation per year allowing populations to build fairly quickly.

Senecio vulgaris stems and leaves can both host the Cineraria leaf rust (Puccinia lagenophorae). It is also host to the black hairy caterpillars of the magpie moth (Nyctemera annulata). http://www.terrain.net.nz/friends-of-te-henui-group/moths/magpie-moth.html

Thanks to Wikipedia for text and Information: http://creativecommons.org/licenses/by-sa/3.0/