Stern's Medlar, Revisited

Way dorsum inwards the Dark Ages of the Fruit Blog, dorsum when I truly wrote long articles, I wrote an post on medlars, which mentioned Stern's medlar, aka Mespilus canescens. I've ever been fond of Stern's medlar, generally because I'm fond of outliers inwards general, in addition to this affair is definitely an outlier.

The genus Mespilus has long been i of those unmarried species genera, consisting only of M. germanica, the European medlar. So the regain inwards 1970 of a medlar species, a hemisphere away from all other naturally occuring medlars, inwards Arkansas of all places, is sure as shooting surprising. The fact that it exists only on i site, amongst only 25 individuals, that it only rarely flowers, in addition to that it turns out to live triploid, are that much to a greater extent than unusual.

In fact, belike also odd to live the existent deal. Influenza A virus subtype H5N1 piddling spell agone I had a nifty electronic mail from Thomas Frothingham, who has worked amongst M. canescens, amongst an update on the latest thinking on the species. I'll repost it hither verbatim, rather than but paraphrasing his whole alphabetic quality for you:

I happened across your website today, in addition to I idea I would travel yesteryear along some information well-nigh the Stern's medlar. In a onetime job, I worked extensively amongst this species inwards situ, at the Konecny Grove Natural Area. There has ever been contestation well-nigh the taxonomy of this really rare plant, but the latest thinking, based on the genetic analysis of the entire Crataegus tribe yesteryear physician J.B. Phipps [EFL: The newspaper is truly yesteryear Lo et al., non Phipps, though Phipps has been a prolific researcher inwards the champaign of Crataegus in addition to Mespilus taxonomy], is this: the Stern's medlar is an accidental hybrid betwixt The huckleberry hawthorn (C. brachyacantha) in addition to the European medlar, Mespilus germanica. I tin flaming transportation yous the master copy article if you're interested. It seems probable to me that the germanica plants were brought to the surface area early on inwards the 20th century, when at that spot was an influx of immigrants from the surface area of the Czech/Austrian border region. The influence of these settlers is really evident today: the nearest community is the town of Slovak, at that spot is an Eastern Orthodox church building nearby, the nearest cemetery is named the Czech National Cemetery, etc. Also the surface area is nevertheless populated amongst people of Czech ancestry (the Konecnys, Orliceks, etc).

At i fourth dimension the population of Stern's medlar was managed every bit i of the rarest tree species inwards the world. If the hybrid theory is correct, it may modify that perception. On the other hand, the huckleberry hawthorn is tracked every bit a species of concern, in addition to has been extirpated from the Grand Prairie part of eastward Arkansas (the master copy prairie has been almost solely converted to rice production). So the Stern's medlar is at to the lowest degree preserving some of the genetics of a rare species.

To answer some of the questions posted on your blog:

To my knowledge, the Stern's medlar is non available commercially. Any endeavor to marketplace position it would receive got to accept into occupation organisation human relationship the ownership rights of the landowners (the Konecny Grove Natural Area is privately owned, managed through a conservation easement yesteryear a nation agency. It is also non opened upward to the public). The constitute also has some limitations every bit an ornamental: the menstruum of bloom is really short, in addition to the flowers olfactory belongings bad. It has in addition to so far proven impossible to propagate yesteryear cuttings or tissue culture, although I assume it could live grafted. The only reliable method in addition to so far is to carefully dig upward the suckers from but about the base of operations of the raise plant. There are some specimens at the Center for Plant Conservation inwards Missouri, in addition to also I believe at the National Center for Germplasm Research inwards Corvallis, Oregon.

The argue it hasn't bloomed inwards recent years is belike due to the succession process, every bit the canopy closes in addition to the plants are increasingly shaded. The role of prescribed burn in addition to removal of surrounding trees has been implemented to contrary this process. The other employment amongst managing this constitute inwards the wild has been the presence of invasive Japanese honeysuckle in addition to privet. These plants receive got been removed manually, which is really undertaking intensive. The final fourth dimension I saw it, the grove was inwards expert shape. This natural surface area is also the habitat for a number of other rare plants, in addition to and so it volition proceed to live managed carefully, regardless of the conservation condition of the Stern's medlar.

It would live extremely interesting to replicate the master copy cross betwixt the ii presumed raise species-in other words, cross pollinate betwixt a European medlar in addition to the huckleberry hawthorn. The seedlings from such a cross would presumably live Stern's medlars.

He also passed along a re-create of the Lo et al. paper* (which I would live happy to percentage amongst whatsoever i interested). It's non the easiest reading, at to the lowest degree from my betoken of watch (as much every bit I similar taxonomy I regain taxonomy papers mind-numbing), but buried inwards at that spot are the evidences for a hybrid beginning of M. canescens:

1. Nuclear sequence information showed M. canescens shared a recent mutual ancestor amongst the M. germanica samples, but chloroplast sequence was truly much to a greater extent than closely related to C. brachyacantha.


2. Stern's medlar shares many characteristics amongst C. brachyacantha that it does non amongst M. germanica: petals that plow orangish upon drying, multiflorous inflorescences.


3. C. brachycantha occurs naturally inwards Louisiana, eastern Texas, in addition to side yesteryear side portions of Oklahoma in addition to Arkansas. M. germanica, spell native to Europe, is recorded to receive got been grown inwards Louisiana every bit long agone every bit 1893, placing the ii species inwards unopen proximity of the only known site of Stern's medlar.


4. Both sexual (×Crataemespilus) in addition to graft (+Crataegomespilus) hybrids betwixt Crataegus in addition to Mespilus. (I've discussed the full general promiscuity of the whole Mespilus / Crataegus / Sorbus / Pyrus / Amelanchier companionship before).


5. There are a lot of reasons to reconsider Mespilus' standing every bit a distinct genus in addition to include it inwards Crataegus.

They basically suggest the next scenario for the beginning of M. canescens:

• Sometime, belike 150-200 years ago, pollen from cultivated medlars was transferred to a blossom of huckleberry hawthorn, resulting inwards hybrid seed.


• The resulting seed produced hybrid individuals. However, because of differences betwixt the raise species, meiosis was irregular in addition to the hybrids were largely infertile.


• The only feasible gametes produced yesteryear this main hybrid would receive got been unreduced, in addition to thence diploid.


• With these unreduced ova, occasional seed ready mightiness receive got occurred, in addition to inwards those cases the pollen raise could receive got been either a medlar or some other native diploid hawthorn (possibly red-fruited, similar M. canescens).


• Stern's medlar is the number of these secondary hybridizations.

I receive got to acknowledge they lay out a pretty compelling case, both for revoking species condition for M. canescens (they suggest designating it Crataegus ×canescens) in addition to for absorbing Mespilus into Crataegus. But my personal taxonomic organisation is based to a greater extent than on watch than on anything else, in addition to I'm definitely a splitter, non a lumper. So I'm going to hold Mespilus, in addition to I'm going to hold calling Stern's medlar a medlar, because it's cooler that way.

*Lo, E.Y.Y., Stefanovic, S., in addition to Dickinson, T.A. (2007) Molecular reappraisal of relationships betwixt Crataegus in addition to Mespilus (Rosaceae, Pyreae)—Two genera or one? Systematic Botany 32(3) 596-616.

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