GENECOLOGICAL STUDIES OF LEAD TOLERANCE IN GROUNDSEL ( SENECIO VULGARIS L.)

SUMMARY Soils from a range of native British habitats for Senecio vulgaris L. have been found to contain significantly different amounts of lead ranging from several hundred parts per million along roadsides and on rubbish dumps to minute quantities in coastal sandy soils. Root growth of seedlings in simple water culture revealed different degrees of tolerance between topodemes to soluble lead, apparently related to the lead content of the soil. Studies of root growth in a range of native soils suggest a more complex relationship between growth and lead content. The genecological implications of these findings are discussed, including the possibility that lead‐tolerant roadside variants may be of recent origin.