One of the primary non-rhododendron collections that we focus upon and feature in the RSBG is the Gaultheria collection. The gaultherias or “wintergreens’ are a widespread group of plants related to rhododendrons. They are called wintergreen because the species native in eastern North America, Gaultheria procumbens, was one of the few evergreens found growing in the forests that greeted the first colonists upon their arrival in New England. This species is the most commonly cultivated wintergreen due to its hardiness, its use as a dwarf evergreen groundcover and its large red berries. It is also the original source for the flavor wintergreen. On the Pacific Coast of North America, the most commonly encountered species is the much larger-growing, often ubiquitous, Gaultheria shallon, Salal. It is also a fine ornamental but can be a bit of a thug in a smaller garden. We have two other much smaller-growing species of Gaultheria in the west, ovatifolia and humifusa, neither of which is commonly cultivated. There is a fifth North American species, native to the bogs and moist forests of the far north, Gaultheria hispidula, which is often included in the genus Chiogenes. I have killed it many times over the years.
The genus Gaultheria is one that has long intrigued me, being plants of interesting habitats and lands, much like our rhododendrons. I have been very fortunate to have had the opportunity to observe and collect many different species of Gaultheria while traipsing about the Sino-Himalaya. In that region of Asia, the genus is quite diverse with many different species, the majority of them, like our North American natives, fine ornamental shrubs or groundcovers. Among the species that I have introduced from this part of the world are G. pseudonotabilis, with long soft red bristles on the stems and red flowers: G. hypochlora, a small alpine, evergreen ground-covering species with large turquoise fruit; G. praticola, with hairy, deeply veined leaves; G. wardii, with softly hairy stems and light blue fruit; G. dumicola, with large, leathery and smooth leaves with curving impressed veins; G. trigonoclada, a very large species with beautiful foliage and unique “wings” on the stems and many, many others.
One of the most intriguing of my introductions was from a small plant (SEH#1510) that I found growing in deep shade in a forest of Rhododendronprotistum and R. sinogrande. It had the appearance of the widespread and common G. nummularioides which I had observed and collected in many different regions. This one was “different” however and growing in a very unusual habitat for a species that is normally found above tree-line creeping amongst the rocks and dwarf alpine rhododendrons. It was completely prostrate on the ground with perfectly round leaves about three-quarters of an inch long in pairs along the slowly creeping stems. I named it Gaultheria aff. nummularioides.
In the garden, this has turned into a fine, small-scale ornamental ground-cover that we use quite extensively in the RSBG. As is our nature, we took cuttings for a several years and were growing on numerous stock plants and even sold a few through the catalog and on site plant sales. Three years ago, the first of our “freakish” three winters in a row (and still counting I am afraid) took place and the SEH#1510 plants were all killed in their containers, along with a great deal of other material. Fortunately, the plants in the garden were fine and continue to thrive. Among the dozens of pots with now dead Gaultheria SEH#1510, one container stood out. In it we noticed one small green plant – still alive. It was a Gaultheria but it was not the Gaultheria, it looked very similar but yet “different”. True, this mystery plant was growing in a pot in which SEH#1510 had been growing and it did have rounded leaves, but it was “different” and, it was alive. There was no sign of any other life in that batch of rooted cuttings. I pulled it aside and kept an eye on my “mystery Gaultheria”.
In due course, Dennis took cuttings of our small mystery plant and we eventually had a nice little supply in gallon containers. This past September, while pulling plants for a plant sale in Seattle, I noticed a row of my mystery Gaultheria and was delighted to see the clusters of strikingly white flowers that stood proudly forth from the mass of dark green foliage in each container. It was finally blooming and it was definitely different. I took a pot home that night to try and work out my mystery. Very exciting as you can imagine. I’m sure you wish you could have been there.
As expected, it did not key out in the Flora of China and did not fit the description of any known species. It was definitely something new as was my original plant (SEH#1510) which I had also collected for comparison purposes and to finally make a determination as to its proper name. The original collection was indeed close to nummularioides but had the wrong hairs and very different flowers although they were arranged singly in the axils of the leaves as expected in nummularioides and were similar in color, a sort of pink-green. These facts, in combination with its very different and distinct woodland habitat, indicated to me that this was an undescribed, new species. In contrast, the mystery plant had much more tightly urceolate flowers of pure white that were borne in small racemes from the tips of the branches – very different indeed. It also had a much more upright, although still quite low and prostrate habit. I thought about this for quite some time. It looked familiar in some way but I could not quite pull it out (I find that a wee dram of scotch often facilitates the sparking of my somewhat senescent synapses in these situations). Then it hit me, the flowers were similar to those of an alpine dwarf species from the high Himalaya, Gaultheria pyrolifolia. This perfectly hardy species had been growing in the same hoop house as the G. aff. nummularioides (now species nova SEH#1510) before the latter had been killed. The two had obviously crossed and my collection was the mother plant. The seed had germinated in the container under the parent plant and had survived the frozen demise of its mother thanks to the hardiness passed along to it by its high mountain father G. pyrolifolia.
I had solved the mystery of the magic Gaultheria, we had a “natural” garden-origin hybrid! We are stepping up production of this fine plant and hope to release it within a year or two under its own cultivar name.
I can’t believe they pay me for this.