Flora of North America species comparison

Primula mistassinica is the most widespread of the North American primroses, and one of the more polymorphic. It can vary in size, leaf morphology, and amount of farina; it is generally consistent in overall habit and floral morphology. Infraspecific taxa previously recognized include var. intercedens, a farinose form common around the Great Lakes, and var. novaeboracensis, a form without a prominent yellow eye in the corolla tube. Isolated individuals showing these characteristics appear throughout the range of the species, and an extensive examination of the complex by H. W. Vogelmann (1956, 1960) led him to conclude that it is best treated as a single, highly variable species; recent molecular analyses (A. Guggisberg et al. 2006) support this assessment. Around the Great Lakes, the presence of farina on the leaves is especially variable, and can range from extensive to nonexistent. Consequently, it seems most appropriate to recognize a single polymorphic taxon with no infraspecific designations, unless molecular analysis suggests otherwise. Although smaller forms of P. mistassinica often have been confused with other species in sect. Aleuritia, it is usually distinguishable by its relatively large heterostylous flowers with lavender corollas.

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

Primula borealis varies in height, leaf morphology, and amount of farina, characters that are all influenced by ecology and phenology. Exposed dune populations are often composed of depauperate individuals; inland populations in protected or nutrient-rich sites can contain individuals over 10 cm in height with more flowers. Younger individuals are almost always farinose; farina sometimes disappears later in the growing season. The species characteristically shows a broad corolla and a full symmetrical umbel on a relatively short scape giving a top-heavy appearance at anthesis. Involucral bracts are saccate or gibbous, in comparison to the often sympatric species P. anvilensis and P. nutans, with plane and auriculate bracts, respectively. Inland populations previously identified as P. borealis should generally be placed under P. mistassinica, which can be distinguished by its more delicate appearance and usually efarinose vegetative parts. Plants from near Kotzebue, Alaska, called P. mistassinica by L. A. von Chamisso and D. F. L. von Schlectendahl (1826–1836) belong to P. borealis.

In the Russian Far East and Japan, it is difficult to separate the North Pacific complex centered on Primula modesta Bisset & S. Moore (including P. ajanensis E. A. Busch, P. fauriei Franchet, P. kawasimae H. Hara, and P. matsumurae Petitmengin) from the complex centered on P. borealis. These show morphological similarities; they differ in chromosome number. No recent comprehensive systematic work has been done on the North Pacific representatives of sect. Aleuritia; molecular and morphometric analyses may help clarify phylogenetic relationships and taxonomy of these taxa.

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