Senecio vulgaris L. subsp. denticulatus (0. F. Muell.) P. D. Sell and S. vulgaris subsp. vulgaris var. vulgaris on Jersey (Channel Islands)

Evidence obtained from comparative cultivation confirms that Senecio vulgaris subsp. denticlIlatus (Asteraceae) and its presumed derivative var. mlgaris differ consistently in a number of morphological and life history characters. Field studies on Jersey revealed that both taxa are also ecologically distinct. Subsp. denriclIlallls is only known from coastal areas of dune grassland where it occurs on soils which have large amounts of carbonate and low amounts of mineral nutrients. Its associates include other winter-annuals and species of Mediterranean
affinity. Results obtained from soil analyses do not provide any meaningful clue to the unusual and disjunct distribution of subsp. denticlIlatlls and several community associates within one of its natural maritime habitats (Les Quennevais). Some observations on the pollination strategy, seed production and predation damage of subsp. denticlIlatus are reported. In contrast to subsp. denticulatus, var. vulgaris occurs in man-disturbed inland r and coastal localities throughout the island. Both taxa seem to interact along an extensive coastal hybrid zone.
particularly in the disturbed area north of Les Quennevais. Progeny-analyses of both short Iigulate and discoid phenotypes from Les Quennevais showed them to produce patterns of germination, phenological and leaf shape characteristics typical of subsp. denticlIlatus. It is concluded that the low nutrient-supplying power of the Quennevais area is a factor of importance in limiting the distribution of the vaT. vulgaris genotypes to areas outside Les Quennevais. Information on the former distribution of subsp. denriculatus on Jersey suggests that its
habitat is seriously endangered from progressive destruction by man.