THE OCCURRENCE OF SENECIO VULGARIS L. VAR. VULGARIS AND S. × HELWINGII BEGER EX HEGI (S. VULGARIS × S. VERNALIS WALDST. ET KIT.) IN ISRAEL

Common Groundsel (Senecio vulgarisL. var.vulgaris(2n = 40)) is widespread in the northern hemisphere. In Israel, judging from a herbarium survey, records taken from the Israel Plant Information Center (ROTEM), and field studies, it has a restricted and widely disjunct pattern of geographical distribution, and, thus, is another example of the comparatively large group of weeds in Israel which are extremely stenochorous. The remarkable gaps in its distribution, from the Upper Golan to Mt. Carmel and to the Jerusalem area, are considered primarily to be the result of paleoclimatic changes, whereas its occurrence outside these centers of distribution is probably related to long-distance dispers…

Evolutionary processes in a continental island system: molecular phylogeography of the Aegean Nigella arvensis alliance (Ranunculaceae) inferred from chloroplast DNA

Continental shelf island systems, created by rising sea levels, provide a premier setting for studying the effects of past fragmentation, dispersal, and genetic drift on taxon diversification. We used phylogeographical (nested clade) and population genetic analyses to elucidate the relative roles of these processes in the evolutionary history of the Aegean Nigella arvensis alliance (= ‘coenospecies’). We surveyed chloroplast DNA (cpDNA) variation in 455 individuals from 47 populations (nine taxa) of the alliance throughout its core range in the Aegean Archipelago and surrounding mainland areas of Greece and Turkey. The study revealed the presence of three major lineages, with largely nonove…

Major gene effects during weed evolution: phenotypic characters cosegregate with alleles at the ray floret locus in Senecio vulgaris L. (Asteraceae)

SELFING ABILITY AND MALE STERILITY IN SENECIO VERNALIS WALDST. ET KIT. (ASTERACEAE) FROM ISRAEL

Two major findings relating to the breeding system of Senecio vernalis from Israel are reported. First, isolation experiments failed to confirm the existence of a widespread, truly self-compatible and predominantly self-pollinating breeding system in Israeli populations of S. vernalis. However, a single S. vernalis plant derived from a natural stand at Jerusalem was found to be self- compatible and strongly self-pollinating. In its progeny, there were signs of inbreeding depression commonly associated with selfed offspring of outbreeding species. Selfing ability ratios in this progeny indicate a single dominant gene for selfing ability in S. vernalis. The implications of these observations …