| Abstract: | Data are furnished respecting the average output of fruits ofPulicaria vulgaris and the ‘reproductive capacity’is estimated as about 2,300. Germination experiments are describedthat show this to be quasi-simultaneous both in light and indarkness. This is contrasted with the more prolonged germinationof P. dysenterica. The seedling of P. vulgaris has a prominentlydeveloped collet which bears numerous supporting root-hairs.Comparison of the effects of homogeneous and heterogeneous competitionin cultures indicate that this may be an important factor indetermining the predominant occurrence of P. vulgaris in habitatspoor in bases. Viviparous germination is recorded; this hazardand the late maturation of fruits are suggested as possiblefactors determining the ‘continental’ type of distributionof this species. Despite its reproductive potential and effective dispersal P.vulgaris has markedly diminished in frequency and this, it issuggested, may be a consequence of successional repression. |
