The influence of high temperatures on germination of four Cistus andfive Halimium taxa is analysed. Seeds were heated to a range of temperatures (from 50 deg. C to 150 deg. C) and a range of exposure times(from 1 to 60 min), simulating those heat conditions registered on the soil surface during wildfires. After the thermal pretreatments, seeds were sown in plastic Petri dishes and monitored for germination over 60 days. For all the species, germination was increased significantly over the control set (untreated seeds) by at least one of the thermal pretreatments. Temperatures of 120 and 150 deg. C were the mostefficient temperatures promoting seed germination, although germination was interrupted at 150 deg. C if exposure times were equal to or longer than 5 minutes for the majority of species. The preheating at 50 deg. C was effective only for C. populifolius, but only at long exposure times (60 min). H. atriplicifolium had the highest heat requirements for stimulating germination, requiring at least 120 deg. C for5 min. H. halimifolium subsp. halimifolium seeds showed the highest heat resistance: the final germination level reached at 150 deg. C for 7.5 minutes ranged between 52.5 and 55.5%. The germination rates after preheating were much lower than in mechanically scarified seeds, and closely resembled those of the untreated seeds. In general, species sharing the same habitat showed different heat requirements in promoting germination. For C. crispus and H. halimifolium subsp. halimifolium, the experiment was carried out on seeds collected from two different localities. For both species the germination patterns were similar between populations, although some high temperature pretreatments showed different germination percentages. [ABSTRACT FROM AUTHOR]