Serotiny in Melocactus matanzanus (Cactaceae) and role of cephalium in dispersal of seeds after the individual's death

Serotiny is a strategy in which the retention of mature seeds in parent structures allows plants to cope with environmental variability like heat, drought or fire. Although this phenomenon might be common in Cactaceae, and particularly in Melocactus, it has generally been scarcely addressed. The main goal of our work is to investigate if there are seeds hidden in the cephalium of Melocactus matanzanus and if there are, determine whether or not these seeds maintain their viability. We also discuss some advantages the cephalium may offer as diaspore after the death of individuals. Cephalia collected from dead individuals were divided into four slices and their seeds counted; we also assessed the viability and photoblastic response of the seeds by using growth chambers at 25/30 degrees C, and by a cut test on the seeds that did not germinate. Our results showed retention of viable seeds of different ages in all slices of the cephalium. Seeds were photoblastic positive with germination between 11-22% and viability above 50% in the portion of the lots that did not germinate.