Eupatorium x pinnatifidum
Distinguishing Features: this name applies to plants that are hybrids between E. capillifolium and either E. perfoliatum or E. serotinum - they have leaves that are dissected as in E. capillifolium, but with broader segments; the heads do not consistently have 5 flowers, but may have 6-8 flowers per head.
Habitat: wet, open areas.
Geographic Distribution: sporadically occurring in the southeastern U.S., in areas of overlap of its parents.
Similar Species: Eupatorium capillifolium consistently has 5 flowers per head, and narrower leaves.
Molecular Data : samples of E. x pinnatifidum (DNA #s 2033, 2034, 2830, 2841) are characterized by indel polymorphisms and bp polymorphisms; based on different patterns of the polymorphisms, the second parent can be identified as either E. perfoliatum or E. serotinum; no morphological differences have yet been identified to determine the parentage of the hybrid.
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