This month’s feature is a little unusual, in that it is a correction to a previous month’s feature. An astute reader pointed out that the picture included with the write-up for “native” birchleaf spirea was, in fact, of a non-native species from Asia. Apparently, confusion surrounding the naming of this branch of genus Spiraea has resulted in many nurseries mistakenly marketing this non-native variety as native. So, let’s do a deep dive on nomenclature and characteristics of these two species!
Previous naming convention had Spiraea betulifolia as a binomial encompassing the Asian and native species, the latter being distinguished as the variety S. betulifolia var. lucida. The native species–sometimes referred to as “shiny-leaved spirea”–has since been reclassified as S. lucida, but the old nomenclature persists, which has resulted in S. betulifolia being sold as a native. If the tag might be wrong, what does the savvy native gardener need to look for?
The main difference between S. betulifolia (non-native) and S. lucida (native) is found in the flowers. Blossoms on S. betulifolia have rounded, almost fused petals, and lack prominent stamens (so nothing protrudes from the middle of the flower). S. lucida, by contrast, has flowers with distinct, somewhat pointy petals, rather smaller and less obvious than those of S. betulifolia, with 25-50 very prominent stamens, giving the flower an almost furry look; this is enhanced by the clustered nature of the inflorescence. True confessions: I have long wondered why the “same” Spiraea species I have planted in my front and back yards looked so different from one another–apparently, the ones in front are the Asian species, while the one in back is the native one!
The other difference between the two species–as I’ve discovered–is that the native one will, in fact, spread by stolons, albeit less wantonly than its pink-flowered cousin, S. douglasii. So, the tradeoff for having the wildlife benefits of the native species is…providing more benefits through having it expand!
