Two new taxa in Stipa L. Sect. Leiostipa Dumort., S. alba and S. letournexii ssp. ignea , are described from southern Tunisia (northern Africa). In addition, the S. letournexii complex is reviewed and a new combination, S. letournexii ssp. tunetana (H.Scholz) F.M. Vázquez, is presented.
Few studies have determined the influence of acorn size on germination and predation percentage at tree level. To evaluate the seed size influence at individual tree level, trees producing two different sizes of acorn were chosen. Our results show that smaller acorns were significantly more infested (49.6-75.3%) than larger ones (11.0-27.33%). About germination, big acorns achieved the best germination percentage compared to the smaller ones (18% in infested and 76% in sound acorns for the small acorn group versus 69.3% in infested and 93.3% in sound acorns belonging to the big acorn group). We also found that there was a difference in behaviour between big and small seeds at tree level. The same size belonging to different functional groups presented a difference at the behavioural level per tree. Infested small acorns from trees 8 and 10 had only 33 and 13% germination, while big acorns from trees 2, 3, and 6 (there was no difference between both sizes) presented 67, 97, and 83%, respectively. These results indicate that the production of acorns with two different sizes could be a strategy for species regeneration, producing each size for a different purpose.
Abstract.-The interest to revision of the Thymus genus in the southern westernIberian peninsula is important to comprehension of the taxonomy and evolution process in the genus. Biosystematic study of the subsect. Thymastra (Nyman ex Velen.) R. Morales of the Thymus genus revealed the existence of two new subspecies: Thymus camphoratus subsp. congestus subsp. nov. and Thymus capitalletus subsp. anomalus subsp. nov., and a new variety: Thymus camphoratus subsp. camphoratus var. grandiflorus var. nov. Also are typified all the taxa associated to the subsection Thymastra (Nyman ex Velen.) R. Morales.
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