Eupatorium hyssopifolium
Distinguishing Features: Leaves are linear, often whorled; the axillary buds tend to emerge, giving the nodes a bushy appearance.
Habitat: old fields, open areas .
Geographic Distribution : the diploid phase is restricted to northern Florida and southern Georgia; presumed autopolyploid apomicts extend up the east coast as far as New Jersey and New York and west along the Gulf Coast to Louisiana.
Similar Species: Eupatorium leucolepis and E. mohrii have narrow leaves, but they are not whorled, and the axillary buds are either totally suppressed or grow out to full length in these. The only other species of Eupatorium s.s. to regularly have whorled leaves is E. semiserratum, and its leaves are shorter and broader. Eupatorium serotinum, E. semiserratum, and E. linearifolium hybridize with E. hyssopifolium, and the hybrids (which are difficult to distinguish from one another) look very much like E. hyssopifolium but have broader leaves.
Molecular Data : samples of E. hyssopifolium differ in ITS sequence from all other species.
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