Eupatorium subvenosum
NOTE: this combination has not yet been made. This taxon has been previously recognized as E. album var. subvenosum, but molecular data show that it is a hybrid-derived apomict that involves E. petaloideum rather than E. album as one of its parents, so it is not appropriate to place it within the latter. In other cases within Eupatorium allopolyploid apomicts are recognized as distinct species if they are distinctive morphologically.
Distinguishing Features: involucral bracts are white in color, outer ones have glands; leaves are less than 60 mm long, and are trinerved, with the three major veins diverging at the base.
Habitat: sandy open pinewoods.
Geographic Distribution: narrowly distributed primarily in New Jersey and Delaware
Similar Species: Eupatorium petaloideum has more attenuate involucral bracts that completely lack glands and pinnately veined leaves; Eupatorium album has larger leaves that are pinnately veined
Molecular Data : samples of E. subvenosum (DNA #s 2042, 2211) have ITS sequences with a pattern of indel and bp polymorphisms that would be produced by a combination of E. petaloideum and E. hyssopifolium.
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