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Abstract

The following zones are to be distinguished in the sinflorescences of Oreobolus: basal intemode of the culm, branching zone of the culm, distal intemode of the culm and the pseudospikelet or staquioide. The sinflorescence as well as the paraclades of Oreobolus goeppingeri appear as the most reduced among the species of Oreobolus referred to in this paper. On the other hand, the foliar nature of the tepals of Oreobolus can be demostrated by comparing them with vegetative leaves. Tepals are strongly modified leaves, incorporated to the terminal flower of the spikelet, and as such, they have to be considered as true perigonial elements. The insertion of the perigonial bristles of the floers of Dulichium arundinaceum at different levels of the floral axis can be explained by considering that they are homologous to vegetative leaves. The ontogeny of different cyperaceous flowers does not support Matfeld's sinantium theory. The hairlike structures that surround the flowers of Eriophorum species are unique structures that originate "de novo" from the semicucular meristematic protuberance, which result from enlargement and fusion of the individual perigonial primordia.