The analysis of fossil stomata reveals the early postglacial presence of Pinus sylvestris at two sites in the Scottish Highlands, 1600 and 600 years prior to the arrival times indicated by traditional palynological methods. Fossil stomata provide unambiguous evidence of past local presence for Pinus sylvestris, which produces abundant and widely dispersed pollen, revealing its presence when pine pollen frequencies are as low as 0.4%, considerably below the commonly adopted minimum frequency threshold of 20%. Thus a species may be present for hundreds to thousands of years before expansion of the local population is registered in the palynological record. This has significant implications, not only for the initial spread of pine throughout the British Isles, but more generally for analyses of the continental-scale migration of temperate and boreal forest taxa based on palynological data. Failure to differentiate effectively among the processes of arrival, establishment, and expansion in analyses of plant migration rates and patterns means that many existing reconstructions of postglacial colonization may, in actuality, represent the expansion of populations over time, rather than the initial spread of species.