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When substantially-different fuel types are introduced to plant communities, several elements of fire regime can change. Species that are photosynthetically active during the dormant season of the species that typically carry fire (such as C3 grasses in C4-dominated grassland) can have such high live fuel moisture so as to reduce the intensity and spatial extent of fire. But this phenomenon has been described most often within the context of alien plant invasions, and not native plant species in natural ecosystems. In the Drakensberg of KwaZulu-Natal, South Africa, patches of Festuca costata, a native C3 grass, are interspersed in grassland comprised of Themeda triandra and other C4 grasses. We show that in the fire-prone weeks prior to the first spring rains, fine dead fuel moisture in Drakensberg grassland is around 30% while live F. costata moisture ranges from 100-200% moisture on a dry-weight basis. We use fire behaviour modelling software to demonstrate how high live fuel moisture might reduce fire spread rate in the Drakensberg. We also use a spatially-explicit fire spread model to test how patch size might reduce the spatial distribution of fire. We discuss how sufficiently-large patches of F. costata might prevent fire spread and increase fire return intervals in these grasslands. We highlight the effects of fire spread heterogeneity on plant community dynamics in grassland managed with prescribed fire.