Begonia U-521 is a species we got from a customer in Alabama, which has sailed through our winters at JLBG since 2017. Flowering begins for us in early fall, with clusters of large pure white flowers, which hide just below the leaves. For those unfamiliar with Begonia U-numbers, these are assigned by he American Begonia Society for plants new to cultivation that represent potential new species.
This amazing begonia was purchased by begoniaphiles Charles Jaros and Maxine Zinman from the Bangkok Market in Thailand. For those who haven’t visited this amazing marketplace, it’s a massive venue where local vendors (nurserymen and collectors) sell their wares.
It turns out that this species came from the wild via a collector who lives on the border of Thailand and Cambodia, where no plants should be winter hardy here in Zone 7b. We’re not aware of anyone currently working on naming new begonias from that region, so to offer it, we’ll need to assign a cultivar name, which will remain connected to the plant, once it becomes a published species.
History is replete with examples of new plant species that are first encountered by intrepid plant explorers, yet described later by taxonomists. Salvia darcyi was discovered and introduced into cultivation by Carl Schoenfeld and John Fairey of Yucca Do Nursery. Three years later, they guided researchers to the site who subsequently described the species without acknowledging the original collector. It is unfortunate that the act of discovery by those in horticultural circles are so seldomly recognized (not to mention the indigenous peoples who have known many of them for eons).
Upon my first visit to Heronswood in the autumn of 2019 I was shown a splendid robust Begoniawith heavily lobed leaves, short upright stems, and amazing tight-clumping habit with yellow (yes yellow!) flowers. I immediately confirmed that this was a heretofore undescribed species. The plants had been grown from the seed collection made by Dan Hinkley along with fellow collectors and nurseryman, Shayne Chandler and Leonard Foltz, from Arunachal Pradesh India. These plants were shared by Mr. Hinkley with Monrovia who immediately released it under the name TectonicTM Eruption Begonia (Begonia sp. DJH18072).
The unknown Begonia has now been given a formal scientific name Begonia lorentzonii by Swedish taxonomist Eric Wahsteen and the Indian researcher Dipankar Borah, based on two specimens collected by Borah in November of 2018 (incidentally, after Dan Hinkley’s collection). No mention of the plant in cultivation or the contribution of Dan is found in the publication despite the fact that quite a few of the Begonia aficionado crowd around the globe had by then become familiar with the plant. Regardless of the name, this species is among the most spectacular hardy garden plants for cool but not cold climates.
Begonia lorentzonii has proven hardy at Heronswood (zone 8a) where it was left outside with only a covering of leaves and straw in temperatures ranging into the low teens and at least a week long stretch of consistently below freezing temperatures which resulted in ground freeze. It forms 2-2.5’ tall dense clumps with one of the best forms I’ve seen in a cold hardy species.
In late summer through late autumn it is adorned with yellow flowers beset with hairlike projections on the outer surface of the tepals produced on stems that equal or are slightly shorter than the leaves. Begonia lovers should visit the Renaissance Garden at Heronswood to see mature plants in their full glory and a pilgrimage to Heronswood is a must for all hardy Begonia lovers as the collection of rare and unusual cold hardy species is probably the best among our public gardens. While this startling plant appears to be perfectly adapted to life in the mild Pacific Northwest it remains to be seen what its tolerance for heat will be. It was an honor and pleasure to grow and nurture these plants during my time at Heronswood and I must admit my heart and mind will forever be drawn to that sacred space of ground whenever I glimpse a Begonia of any species.