Picea obovata Ledeb.

Picea obovata is an irksome species to describe and discuss in a work focused on cultivated plants. As a wild plant it has the largest range of any spruce, ranging from the Siberian tree line in the north, south to an isolated outpost in the Altai where the borders of Russia, Mongolia, China and Kazakhstan meet. East to west it stretches from the Sea of Okhotsk in far eastern Russia (though remaining west and south of the Verkhoyansk mountains in eastern Siberia) to its western limit somewhere in northwest European Russia (Arkhangelsk, Karelia and Murmansk regions).

In the west of its range Picea obovata is still frequently treated as a subspecies of P. abies, or else its populations in northern Finland and northwestern-most Russia are considered to represent hybrids between P. obovata and P. abies (viz. P. × fennica (Regel) Kom.). Farjon considers it ‘more than likely’ that multiple hybridisation events have occurred due to ‘the repeated retreat of P. abies into refuges that were situated in European Russia during the ice ages. The two taxa mixed in their subsequent recolonisation[s]’ (Farjon 2017). This supposition has since been substantiated by molecular investigations that suggest P. obovata, recolonising European Russia from refuges in the Urals, used refuges of P. abies as stepping stones, leading to hybridisation (Tsuda et al. 2016). It stands to reason that introductions of ostensible P. obovata to European herbaria and cultivation will have included samples gathered in this region of overlap, which might explain why descriptions of P. obovata in European literature are so woefully inconsistent, and why some descriptions (even Farjon’s in A Handbook of the World’s Conifers (Farjon 2017)) seem to mix and match features of the two.

When sampled from the majority of its range – where it does not overlap with Picea abies – P. obovata is ‘very distinctive in its thinner, near-white to yellowish-white branchlets (or on the upper side yellowish-grey) initially densely set with glandular hairs (vs. branchlets reddish-brown and glabrous or with nonglandular hairs); needles light green (vs. dark green), typically shorter […] and thinner […]; and much smaller cones (5–11 cm vs. 10–15<18.5 cm) with rounded scale-tips (vs. tapering to rounded, bifid to blunt)’ (Debreczy & Rácz 2011). At least in the UK, trees adhering to this description are few and far between, and an open mind is as useful an aid to identification as a textbook. The most useful ‘tell’ is a combination of the oft-cited character of very pale, nearly white shoots, and the leaves swept forward and downward below the plane of the shoot, an arrangement only otherwise encountered in P. morrisonicola from Taiwan.

Only very few individuals of Picea obovata have ever been recorded from the UK and Ireland, where the prevailing oceanic climate is a world away from the strongly continental one of northern Eurasia. The Tree Register’s public-facing database lists only twenty, with notes against several of them hinting at varying degrees of confidence in the identifications (Tree Register 2024). It is perhaps no coincidence that some of the trees that have been longest-known, and which today are among the finest examples, grow in some of the coldest parts of the country, particularly inland Aberdeenshire in northeast Scotland and at Dawyck Botanic Garden in the Scottish Borders, both regions where the climate perhaps gets as close to continental as anywhere in these islands, and where trees from 20–25 m have been recorded.

It is perhaps a better prospect in a continental climate, such as the Arnold Arboretum where several accessions are recorded: 354–79 from the Russian Altai is surely genuine and two good trees are recorded, the largest to 21 cm dbh; five other accessions include one of unknown origin and four from northern Finland, from where the potential for introgression with Picea abies must be kept in mind (Arnold Arboretum 2024). Nevertheless, even in areas where it can be grown successfully it cannot be said that P. obovata is particularly ornamental, and on the rare occasions it is cultivated its chief interest seems to be botanical curiosity. A handful of cultivars are known, mostly selected for the intensity of glaucousness in the leaves, of which the best is probably ‘Krylovii’.