Flora of North America species comparison

Primula incana is usually heavily farinose, at least when young, and has relatively tall scapes and tight umbels of homostylous flowers. As with some species of the genus, anthesis often begins before the scape is fully elongated; plants at first are quite small, but elongate throughout anthesis and typically become relatively tall and lanky in age. This has led to confusion with other arctic species, especially P. stricta, which has considerably less farina, a shorter scape, and a more maritime distribution. In fruiting stage, P. incana has been confused with P. laurentiana, which has looser umbels throughout anthesis, larger flowers, and a more eastern distribution. Primula incana generally replaces P. laurentiana to the west and south of Hudson Bay. The single octoploid count for P. incana is questionable; the species appears to be consistently hexaploid in other counts.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

Primula rusbyi has the most southern distribution of the species in sect. Parryi, occurring in the mountains of New Mexico and Arizona, and in Mexico and probably northern Guatemala. It is well-marked by toothed leaf margins and a prominently farina-striped calyx. Typically, its corolla tube far exceeds the calyx. Some individuals from the Sandia Mountains of New Mexico have a shorter corolla tube more or less equal to the calyx; these plants have been described as P. ellisiae. A single population can include individuals of both types, and the difference probably represents only a developmental stage of the flowers or minor morphological variation in some localized populations; preliminary genetic analyses (S. Kelso and P. Beardsley, unpubl.) reveal no substantive genetic distinction between these individuals and those from elsewhere in the range.

(Discussion copyrighted by Flora of North America; reprinted with permission.)