[Trillium-l] Microhabitats

Robin Graham Bell rgb2 at cornell.edu
Mon Jan 19 22:32:17 CET 2015

Hi Dan, The topic of microhabitats is a perpetually curly (& fascinating) one especially for those of us who like seeing plants in the wild as well as the garden. Often, though, I think that we focus on the obvious one, or the one that we can measure or control, to the exclusion of all else. Nor do I think that anyone has it all figured out as critical factors can vary even for one species depending on the environment. For me, when I try to work out what is important I try to think of it as hierarchical. If #1 is OK then #2 might be in play & so on thru as many as seem to be significant. Plus, not all distribution is necessarily the geochemical habitat; pollinators, seed dispersal mechanisms & competition may all be factors as well. With the trilliums that I was familiar with, I came to believe that competition was the most important thing in the eastern hardwood forests. That is what has pushed them into early spring (hence cool adapted) when there is little competition from other forbs or the canopy. I also suspect that this is the factor that makes t's generally favor riparian areas as there is more light than deeper in a forest. In Ithaca I couldn't grow catesbyi or undulatum despite trying to modify my high pH soil. Unfortunately I was never really sure that pH was the critical problem. With undulatum there were almost certainly other factors as well, who knows what was first in the hierarchy? 
	In gardens everyone tries to get the best spot for favored plants even if we don't really know what the best conditions might be. I recall a woodlot in Canada where TRGR were all thru it, but by far the most vigorous plants were those in full sun that had self sown into the bare strip beside the woodlot. I think most of us would not think that TRGR quite likes full sun if there's nothing crowding it out & the temps remain cool. 
	I'm hoping that TRGR will make it here even tho summer temps get above 100 quite regularly but the nights cool down pretty well & humidity is low. I could have as much trouble with some of the westerners as people in the south seem to have. Although there are 3 western species growing within 20 miles of me none grow, as far as I can tell, anywhere on the set of hills I live on. More victims ahead? The one thing that keeps me doing this is that I have even less idea about the native habitats of a majority of the plants in my garden, many of them not influenced at all by human intervention thru breeding or selection. Often all that you get is, likes shade, or prefers acid soil, likes moisture, etc. So there's hope, as well as room for surprise. 
	Robin Bell, Medford, OR. zone 7 or so.
On Jan 17, 2015, at 5:28 AM, Miles, Dan wrote:

> To follow the discussion on adaptability of eastern & western American trilliums on opposite sides of the continent (or the globe):  it would be interesting to know in what microhabitats they are being cultivated where they fail or succeed. 
> In the wild, trilliums do not survive a few feet outside the places where they thrive, due to subtle but critical variations in growing conditions. Surely the same applies to a significant extent even under careful attention in gardens. I agree that night temperature may be critical, if not the primary limiting factor in succeeding with the more fussy species. 
> Some Trillium species and other woodland plants are found only in riparian zones and are often limited to cool, perpetually moist, north-facing slopes, even at high elevations. Even in the Smokies, you do not find Trillium vaseyi, for example, growing on uplands, no matter how rich, even in a high-rainfall zone. 
> Cool air settles in low areas. On a summer evening, when I walk out of my hollow and up to my yard on the ridge less than a hundred feet higher, I notice a dramatic rise in temperature. It can be 20 degrees F cooler at night along the streams. 
> T. Vaseyi thrives here at 700 ft. Above sea level on cool streambanks, but I would not expect it to do as well on the north side of my house, no matter how much attention I may give it there. I would say the same of kurabayashii. I anxiously await the emergence of this species following  planting some young plants last spring in a cool streamside position. 
> All the failures I hear about western species in the East...have they been sited in the kind of cool, moist riparian habitats in which they are found in the wild?  Are they failing simply because of too-high night temperatures?  I realize that not many gardeners are blessed to have a streamside position available. I'll keep you all posted. And thank you, Russ!
> Dan Miles, Virginia Piedmont, zone 7a
> Sent from my iPhone
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