REPRODUCTIVE CHARACTERISTICS AND BREEDING SYSTEM OF SHRUBS OF THE MEDITERRANEAN REGION

1. The reproductive characteristics of 27 species of shrubs of coastal macchia from southern Italy were investigated. 2. There are two main groups of species, anemophilous and entomophilous. 3. Amongst the entomophilous species are two diverging trends in reproductive characteristics, towards either a group of dioecious, small-flowered, fleshy-fruited, few- to one-seeded, vegetatively spreading species or to an hermaphrodite, large-flowered, dry-fruited, many-seeded, non-vegetatively spreading group. 4. The relationships between breeding system and both fruit type and seed number were examined for 129 shrubs of the maquis and 111 of the sclerophyllous forest of the Mediterranean. In both habitats, fleshy fruits and low seed number are significantly associated with dioecy, and dry fruits and single seed with monoecy; only high seed number is associated with the hermaphrodites. 5. A close examination of the breeding system of Phillyrea latifolia at the population level at Castelvolturno indicates that there is unexpected deviation from reported characteristics. This species is characterized by a high proportion of female-sterile plants. These male plants are present in numerical excess and produce greater numbers of flowers per node than their hermaphrodite counterparts. 6. It is suggested that the primary selective factor operating on the diversity of pollination and breeding system in the shrubs of the Mediterranean is resource limitation caused by nutrient and water stress, but there is no single strategy of reproduction adapted to this environment.