Flowering this week in the garden is the little-known, Hydrangea hypoglauca. Hydrangea taxonomy has been in a bit of flux, especially within the group of species that comprise the Hydrangea heteromalla complex. One of the taxonomic segregates from that group is Hydrangea hypoglauca, which hails from forested mountains between 600 and 12,000′ elevation in the Chinese provinces of Guizhou, Hubei, Hunan, Shaanxi, Sichuan, and Yunnan. Our plants were grown from seed collected in Hubei. Our 8′ tall, 5 year-old specimen puts on an amazing show every year, starting for us in mid-July. We think this has tremendous garden potential, and will be taking a few cuttings for the 2026 Southeastern Plant Symposium auction.
A non-gardening family member calls all hydrangea, “high-geraniums” so taxonomy is not a thing with them, bless their heart. You mentioned the taxonomy is in flux? I see the bloom is lacecap; is H. hypoglauca more closely related to H. macrophylla (Bigleaf Hydrangea) and H. serrata (Mountain Hydrangea) both of which are Aisian lacecaps? At first glance Hydrangea hypoglauca and my Eutrochium purpureum/Joe Pye Weed growing in part-sun appear strikingly similar. Convergent evolution? Or perhaps my Joe Pye in part-shade aren’t getting enough sun and are ‘hypo-glycemic’?
Hydrangea hypoglauca is not in the same clade (taxonomic group) with either H. macrophylla or H. serrata. The closest relative is Hydrangea heteromalla. The “lacecap” refers to the number of fertile flowers vs. non-fertile ones, and isn’t usable to distinguish species.