Survival of the fittest?

   
Garden, early December (left), mid-April (right) (click on photos to see larger version)

This side-by-side comparison shows very graphically how bad a hit my garden, and especially my palms, took after this winter.  The photo on the left was taken in early December, after a hard freeze had knocked down the hardy banana (Musa basjoo) but before the series of cold waves we had in January.  The photo on the right was taken just today; daffodils may be blooming merrily but not much else is looking good!  Note the windmill palms: Trachycarpus fortunei "Bulgarian" in the lower left, T. fortunei "Nainital" at upper right, and T. wagnerianus immediately to its left.

The two palms in the upper part of the garden were very badly damaged, with their spears as well as several leaves pulling out.  I've already cut all the fronds off the T. wagnerianus, and about half the fronds from the other two.  This is what they look like now:


Trachycarpus wagnerianus after spear and leaves pulled

Even with this damage, there's a chance they will come back.  For my waggie it's a pretty slim chance, as it suffered damage before the other two and all its foliage was killed (see Waggie vs. Nainital).  I have a bit more hope for the "Nainital", which still has some green in about half of its leaves.  But as I noted yesterday (Bulgarian wins!), my "Bulgarian" is already pushing out new growth, despite looking almost as bad as the "Nainital":


New growth on Trachycarpus fortunei "Bulgarian"

There's a lot of chatter among hardy palm growers, and on various discussion boards, as to the "hardiest" strains of windmill palms.  These are generally grown from seeds of palms known to have survived temperatures at the low end of their cold tolerance--often cold events that killed the majority of palms around them--and are identified with quasi-cultivar names based on their origin like "Taylor", "Bulgarian", or "Nainital".   Many growers now consider "Nainital" to be one of the superior hardy strains, whereas many are noting their "Bulgarians" did not fare as well.  The reverse was true for me, although my "Nainital" was my clear winner in previous years.  (Many growers still swear by "Taylor" but when I grew one of these several years ago, it suffered spear pull even after mild winters and I finally removed it after one winter when it suffered massive damage.)  

Different growers seem to have very different experiences, vouching for one or another of these strains but with no particular consistency that I can see.  Why does one palm live, and another one die?  I have to wonder, when particular palms survive after a winter that kills so many others, is it really due to any kind of intrinsic/genetic cold tolerance, or is it just plain chance, or due to non-genetic influences that we still don't understand?  There are a lot of extrinsic factors like soil composition and moisture, proximity to buildings, exposure to winter sun and wind, and who knows what else that can all make a big difference to their survival but are hard to control.  I hope to harvest seeds from my "Bulgarian" (which bloomed for the first time last year, revealing itself as a female) but in the end, are we kidding ourselves that we can actually select for hardier strains by planting seeds from the survivors?


Female flowers on T. fortunei "Bulgarian" (May 2013)