Picea × albertiana S.Br.

The name Picea × albertiana traditionally covers hybrids of White Spruce (P. glauca) and Engelmann Spruce (P. engelmannii) wherever and however they occur. Although Brown originally described it as a nothospecies in 1907, Beissner soon amended it to a variety of White Spruce, viz. P. glauca var. albertiana, and this use is still more commonly met with in textbooks, databases and on labels than is Brown’s original rendering.

Indeed, this is a particularly contentious taxon. Arguments persist to the present day as to which entity Brown’s name actually represents, with Björk & Goward (2022) arguing, rather convincingly, that Brown’s original description of Picea × albertiana, although clearly matching his type specimen, is not representative of trees intermediate in features between P. glauca and P. engelmanii, nor, in their experience, are trees representing such a cross particularly common in the area where it was described from. They instead consider Brown’s name to represent hybrids of P. glauca and P. mariana, and propose a new name for hybrids of P. glauca and P. engelmannii, P. × darwyniana, which are indeed ‘common and widespread’ in British Columbia (Björk & Goward 2022).

On the other hand there are those who take an orthodox approach, maintaining that Picea × albertiana represents hybrids of White and Engelmann Spruces, and even treating such hybrids in one of two subspecies depending on the seed/pollen parent combination: P. glauca × engelmannii (= P. albertiana subsp. albertiana) and P. engelmannii × glauca (= P. albertiana subsp. ogilviei) (Strong & Hills 2006). As a co-author of the name P. × albertiana subsp. ogilviei, and given this history of interest and the approach taken at the time, it should not come as a surprise that Strong thoroughly refutes Björk & Goward’s findings, citing a failure to scrutinise P. × albertiana isotypes (which he considers do not fit glauca × mariana, although it would not be the first time in history that type material was found to represent multiple taxa) and considering their P. × darwyniana illegitimate on the grounds that it represents his earlier, validly published subsp. ogilviei (which is itself superfluous) (Strong 2023).

Another problem is that even when it is considered to represent hybrids of White and Engelmann Spruces, many textbooks consider Picea × albertiana to be distributed far beyond the area of overlap of those two species, which is restricted to southern interior British Columbia, southern Alberta, and Montana. Plants of the World Online, for example, also includes Yukon, the Northern Territories, Saskatchewan, Manitoba and South Dakota in P. × albertiana’s distribution (Plants of the World Online 2024), probably based on isolated specimens from these areas that seem to match P. × albertiana. (It is worth observing that while P. engelmannii does not occur in those additional Canadian Provinces named above, P. mariana does).

Clearly there are unanswered questions around the naming and distribution of P. glauca hybrids with both P. engelmannii and P. mariana. It seems likely that at least some cultivars nominally listed under P. glauca will actually be derived from one of these hybrids, but until such time as we gain a better understanding of these hybrids and their distributions, we will continue to discuss cultivars of known or suspected hybrid origin under P. glauca itself.