Senecio eboracensis

York radiate groundsel is an annual herbaceous plant that sets its seed within the 3 months that it takes this plant to mature from germination to the upwards of high adult plant. With yellow daisy-like flowers from its Sicilian parent (S. squalidus) but also with the less-promiscuous habits of its native parent (S. vulgaris), this member of the genus Senecio is morphologically distinct from related species. :Leaves and stems S. eboracensis have large many lobed leaves divided into slender segments, the clefts not reaching the midrib. The stems are mostly erect to ascending with an occasional horizontal base section up to with 'adventitious roots' at base. The upper and lower leaves petiolate and lobes appearing at quarter whole leaf lengths along the midrib. The upper leaves are generally more deeply lobed and in lobed pairs. Leaves on plants grown in fertile soils or in greenhouses can be much more luxurious and more highly dissected (or more finely divided into slender segments) up to x with lobes appearing at fifth whole leaf lengths along the midrib. Leaf edges throughout are dentate or sometimes divided into lobes. :Flowers York groundsel has flower-heads that are more showy than those of its parent groundsel. The flower-head, found at the tips of the plants (apical) appearing in clusters (an inflorescence) usually consist of three to seven florets grouped in a corymb; at first dense and leafy but eventually less dense with peduncles 5 to 20 millimeters (0.2 to 0.8 in) which get longer when fruiting (up to 25 mm (1 in)). The flower-head is broadly cylindrical 10×4 millimeters (0.4×0.16 in), becoming slightly bell shaped) when the bright yellow ray florets open. Involucral bracts sparse (4-8), elongated (3.5–4 mm), usually without black tips. The ligules are narrow, 5 to 7 millimeters (0.2 to 0.24 in) long and 1.5 millimeters (0.06 in) wide), occasionally becoming revolute. :Seeds The achenes can be 2.5 to 3.5 millimeters (0.1 to 0.15 in) long, are straight and shallowly grooved. The smooth ribs are hairless while the grooves are covered with hairs. The silky white, umbrella-like pappus readily detaches from the fruit when ripe. ==Name==

The word Eboracum, the classical name of York, was chosen in the year 2000 to describe this tetraploid hybrid derivative informally named 'York radiate groundsel' at the time a formal description was made. ==Distribution==

York groundsel occurs on disturbed ground, car park perimeters, pavement cracks and other urban/industrial sites; specifically in disturbed areas near to the railways in York, England. while the other parent Senecio squalidus was introduced from Mount Etna in Sicily in 1690 to the Oxford Botanic Garden in England, and was soon spreading along the railways and throughout the country. It became near-extinct by the 1990s probably due to the use of weed-killing chemicals and ground disturbance. A programme of reintroduction in York resulted in flowering plants in 2023 and a sustainable population of several thousand plants. ==Evolution==

Senecio eboracensis is a hybrid species whose parents are the self-incompatible and promiscuous Sicilian Senecio squalidus (also known as Oxford ragwort) It is thought to have resulted from backcrossing of the F1 hybrid of its parents to S. vulgaris.), now common in Britain, and the allohexaploid S. cambrensis, which according to molecular evidence probably originated independently at least three times in different locations. Morphological and genetic evidence support the status of S. eboracensis as separate from other known hybrids. ==See also==