The Dryopteris kinkiensis is still looking fabulous in the garden as we inch closer to spring. This little-known Chinese native fern was first brought into the country as spore by plantsman Hans Hansen in 2005. It is also native to Japan, Korea, and Taiwan. The name was originally published for the material in Japan, named after the Kinki region. The foliage is a very glossy dark green with a nearly plastic texture. We estimate hardiness to be zone 7a-9b, but we could be greatly underestimating its potential in that regard.
The cold and raw weather of late autumn and winter provide the perfect opportunity to sit down with the dissecting scope and put our ferns through the identification mill. Often gardens and nurseries receive a plant into their collections from an exporter or collector who has put their best guess on the identification. After many years in cultivation, we realize what we thought was the right species name for our specimens is incorrect. Today’s nasty weather provided the opportunity to examine, in detail, one of our favorite evergreen fern groups – Dryopterissection Variae.
These firm-leaved evergreens produce thick-textured, durable, medium-sized fronds of varying shape but all display a noticeably longer basioscopic pinnule (that’s fancy talk for the lowest, innermost segments of the divided leaves). All members of the section that we have grown have proven to be very adaptable to our hot, humid summers and unpredictable winters if grown in shade or partial shade in moist woodland garden conditions. The fronds tend to burn if they receive too much light. They are late risers in the spring often not producing a new flush of leaves until late spring or even early summer.
At the beginning of the day, we started with 8 accessions of Dryopteris varia, 2 accessions of Dryopteris bissetiana, 6 accessions of Dryopteris formosana, one accession of Dryopteris saxifraga and a couple of unknowns. From these numbers you would expect that the one plant we would know best would be Dryopteris varia.
Dryopteris bissetiana comparison
Well…it turns out all the plants we had received or had identified as D. varia were actually representative of other taxa. If you’ve never tried keying ferns using The Flora of China or The Ferns and Fern Allies of Taiwan, you would have no idea just how difficult a process this is. The floras of these areas are notoriously difficult to use and often contradictory or difficult to assess using illustrations or pictures (yes even plant taxonomists google names to find images). Very quickly we became intimately familiar with the nature of the stipe and rachis scales, frond outlines, and disposition of the vestiture (yeah you think that sounds easy, right?).
We found most of our collection was actually composed of Dryopteris bissetiana, which are mostly from collectors who sent us tentatively identified wild-collected material. The majority of these were from Sichuan in China, however one very beautiful, deep green and glossy selection that is only half the size or less of the others was Tony’s collection in Korea, and has tentatively been identified as Dryopteris saxifraga. All of these are remarkable garden plants, but we are very excited to some day offer the choice dwarf from Korea which we have named ‘Cheju Dwarf.’
It was a pleasant surprise to find that our collections of Dryopteris formosana were correctly labelled, but we weren’t prepared for there to be two distinctly different looking plants represented in our garden that are the same species.
One of these is the plant that has been shared among fern enthusiasts for some time that is the typical sexually reproducing diploid. The other is an apogamous triploid that looks like a completely different species. In a diploid (like you and I) the pairs of chromosomes uncouple and one copy of each goes into making the male and female gametes.
Dryopteris formosana forms
Thus, each gamete has only one set of each chromosome (haploid) and when combined with those from the complementing sperm or egg results in another diploid. Plants sometimes have a mistake in their cells that lead to the production of gametes with twice as many chromosomes as they would normally have and when such tetraploid plants breed with a diploid the result is a gamete with 2 copies of each chromosome combining with a gamete with only one—thus triploid. In your average plant this triploid is a dead end for reproduction by seed or spore because they have an uneven base number 3—which can’t be divided into an equal number of chromosomes, so it is sterile.
Dryopteris formosana comparison diploid left triploid right
This triploid avoids the curse of having an uneven number of chromosome pairs by avoiding sexual reproduction and producing spores that will result in new plants without the traditional interplay of sperm and egg on a germinated gametophyte (yes apogamy in ferns is still legal in all states and countries). We were puzzled when two very different looking ferns keyed to the same species. Everything that was in the key matched. The bullate hairs, the shape, the color, the basioscopic pinnae and the overall shape.
Our taxonomist, Zac Hill, very quickly uncovered a recent paper by Kiyotaka Hori, et al (2017) which explained and beautifully illustrated our conundrum. The triploid produces a wider, far more pentagonal frond with a less erect nature in the way the blade is held, and a deeper green, highly pleasing color—now that’s pretty darn cool! This new discovery we have named ‘Yushan 2 X 4.’ A new plant for us all to grow in the years to come and now you know why we chose the name diploid (2) X tetraploid (4).
Dryopteris formosana triploid
Now that we realize we grow seven different forms of Dryopteris bisettiana, each collection will be given a cultivar name, which will refer back to their specific origin and uniqueness.
Every day brings discovery when you manage a collection of 30,000 taxa but one thing we know for sure, these are amazing, well-behaved, slow growing woodland plants that are the essence of what makes Juniper Level Botanic Garden so amazing.
Patrick McMillan, director of horticulture and gardens
Literature cited:
Hori, Kiyotaka, L. Kuo, W. Chiou, A. Ebihara and N. Murakami. 2017. Geographical distribution of sexual and apogamous types of Dryopteris formosana and Dryopteris varia (Dryopteridaceae) in Taiwan. Acta Phytotax. Geobot. 68 (1): 23-32.
Here’s a fun textural image from the woodland garden, featuring Hydrangea quercifolia ‘Little Honey’, Farfugium japonicum ‘Aureomaculatum’, and Athyrium ‘Ocean’s Fury’. Off to the left side are three more ferns, Dryopteris x celsa, Adiantum capillus-veneris, and Ctenitis subglandulosa.
We’ve been working on upgrading many of the temporary gates throughout the garden, our first few, which went in this year are all designed by NC sculptor Jim Gallucci, from photos we took in the JLBG Gardens. We all need more art in our gardens…Enjoy!
The rare Dryopteris x australis is looking superb in the garden this week. This Southeast native, naturally-occurring hybrid will grow in sun or shade and in wet or average soils. Despite its deep southern roots, it’s fine outdoors in Zone 5a. 4′ tall..pretty amazing!
There’s so much going on in the garden now, it’s hard to know where to start. The ferns are looking fabulous, and one of our favorites is the native Dryopteris x australis. Yes, “australis” means from the south. This 3-4′ tall fern grows well in moist or fairly dry soils. Here’s the clump beside our shipping office.
Epimedium ‘Splish Splash’ is in its second flowering spurt of the spring. This re-flowering Plant Delights introduction is really quite special, both in foliage and in flower.
Here’s our clump of Baptisia ‘Pink Truffles’ from the breeding work of our friend Hans Hansen at Walters Gardens. This is the first named pink flowered baptisia….we are very pleased with its performance.Clematis recta ‘Lime Close’ has been amazing this spring. For years, I was under the mistaken impression that this wouldn’t grow in our heat…I was very wrong. The non-vining Clematis ‘Lime Close’ is often sold under the marketing name Serious Black. I love this plant!
Here’s a new photo of the evergreen Autumn fern, Dryopteris erythrosora ‘Brilliance‘ as it emerges in the woodland garden with its stunning new growth.
