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Spore‐bearing plants are capable of dispersing very long distances. However, it is not known if gene flow can prevent genetic divergence in widely distributed taxa. Here we address this issue, and examine systematic relationships at a global geographic scale for the fern genusPteridium.

We sampled plants from 100 localities worldwide, and generated nucleotide data from four nuclear genes and two plastid regions. We also examined 2801 single nucleotide polymorphisms detected by a restriction site‐associatedDNAapproach.

We found evidence for two distinct diploid species and two allotetraploids between them. The “northern” species (Pteridium aquilinum) has distinct groups at the continental scale (Europe, Asia, Africa, and North America). The northern European subspeciespinetorumappears to involve admixture among all of these. A sample from the Hawaiian Islands contained elements of both North American and AsianP. aquilinum. The “southern” species,P. esculentum, shows little genetic differentiation between South American and Australian samples. Components of African genotypes are detected on all continents.

We find evidence of distinct continental‐scale genetic differentiation inPteridium. However, on top of this is a clear signal of recent hybridization. Thus, spore‐bearing plants are clearly capable of extensive long‐distance gene flow; yet appear to have differentiated genetically at the continental scale. Either gene flow in the past was at a reduced level, or vicariance is possible even in the face of long‐distance gene flow.