Packera plattensis (Nutt.) W.A. Weber & A. Love

Locations ofPackera plattensis (Nutt.) W.A. Weber & A. Love in Virginia

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Detail

Family
Asteraceae
Botanical Name
Packera plattensis (Nutt.) W.A. Weber & A. Love
Common Name
Prairie Ragwort
Synonym(s)
Packera paupercula (Michaux) Á. & D. Löve var. appalachiana A.M. Mahoney; Senecio plattensis Nutt.
Flora of Virginia Name/Status
Packera paupercula (Michaux) A.&D. Love var. appalachiana A.M. Mahoney
Comments
There are two camps of taxonomic opinion about the identity of persistently pubescent plants characteristic of thin woods and barrens in carbonate-rock (limestone and dolomite) regions west of the Blue Ridge. These plants have long been referred to as P. plattensis, a view maintained by FNA, and followed here. A contrasting view based on chromosome numbers (a single count from Virginia) and evidence of hybrid progeny, assigned these plants to a new variety of P. paupercula (P. paupercula var. appalachiana (see Sida 20:605-610 and Novon 18:220-228, for discussion)). This view holds that the Virginia populations are tetraploid but with a base chromosome number consistent with paupercula rather than plattensis. While this view seems to have merit, P. paupercula typically has glabrous foliage while P. plattensis is characteristically pubescent. The source of this pubescence might be learned from allozome or other molecular studies. Other questions remain such as whether all Virginia populations are tetraploid and, if so, whether they all have the same base number. The presence, in these same habitats, of other plant species typically associated with prairie habitats west of the Appalachians suggests that P. plattensis might at least have contributed to the gene pool of our plants. Packera species often hybridize when in contact, so a more complicated evolutionary history is also possible. We maintain the name P. plattensis to, in part, draw attention to the many unanswered questions regarding these plants.
Habitat
Dry, rocky woodlands and barrens over dolomite (rarely limestone), and occasionally mafic or ultramafic rocks; in Virginia, this species appears to be a rather strict magnesiophile, associated almost exclusively with soils of consistently high magnesium and widely variable calcium content. Infrequent and local in the mountains; rare in the Piedmont.
Native Status
Native

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