Diversification of Portulaca oleracea L. complex in the Italian peninsula and adjacent islands ?

摘要

There is an increasing interest in the taxonomy and distribution of the forms of the Portulaca oleracea complex. The information accruing from specimens collected in the Italian peninsula and surrounding islands (Sicily, Sardinia, Corsica and Malta) is here described. Eleven morphotypes were recorded: ‘P. cypria’, ‘P. granulatostellulata’, ‘P. nitida’, ‘P. oleracea’, ‘P. papillatostellulata’, ‘P. rausii’, ‘P. sardoa’, ‘P. sativa’, ‘P. sicula’, ‘P. trituberculata’, ‘P. zaffranii’ and a still unclear form Portulaca oleracea f. Three occur in almost all the Italian peninsula and adjacent islands; three are scattered in the Italian peninsula and in the adjacent islands; the remnant have a distribution restricted to the islands such as Sicily and Sardinia. The morphotypes can be divided into two main categories: seeds smooth, without ornamentations; seeds with ornamentations. The morphotypes with ornamentations are more widespread than smooth ones, probably because seed ornamentations play an important role in seed dispersal, which is perhaps mainly anthropochorous given that P. oleracea is a synanthropic species that can tolerate mechanical disturbance. There are cases of multiple occurrence, as evidenced by the presence of different morphotypes in some of the sites. Such populations can count up to five morphotypes growing together. Seven morphotypes were here recorded from Malta; they are all hexaploid, even those which in other areas are tetraploid.