Introgression between Utricularia oppositiflora and U. dichotoma in the Errinundra National Park

Introgression between Utricularia oppositiflora and U. dichotoma in the Errinundra National Park

I came across this interesting population of Utricularia on the upland escarpment of the Errinundra National Park, eastern Victoria. Two taxa were present – a smaller one resembling U. oppositiflora and a larger one resembling U. dichotoma at a glance. Closer examination, however, revealed morphological inconsistencies that suggest a history of gene flow between the species before the population stabilised into the current taxa.

The smaller plants most closely resembled U. oppositiflora with their shorter scapes, compact blooms, relatively large globular capsules and broad corolla spur. The reduced striations on the upper corolla lip and broader flare on the lower corolla lip are likely conferred by U. dichotoma genes.

The taller plants looked like U. dichotoma in that the blooms were larger and the pedicels were relatively long. Feint striations on the lower corolla lip and a ‘bell’ shaped lower corolla lip are characters conferred by U. oppositiflora genes.

Both taxa were very successful at this site and occupied the flooded heathland adjacent to a creek, growing in shallow pools and sphagnum rafts. Utricularia dichotoma and allied species hybridise rampantly and it isn’t uncommon to find entire populations that are of hybrid origin.

The smaller U. oppositiflora x dichotoma dwarved by the larger U. dichotoma x oppositiflora
U. oppositiflora x dichotoma
U. dichotoma x oppositiflora
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