I drove past a dozen or so Shumards today. Two still had leaves. Was it genetic variation? Old cross expressing itself? Don't know.

ow.. ow.. ow..

learned another new word today ... it hurts.. . who knew there was such a term for leaf retention.. lol ..

i always thought it was a system to protect the buds.. up here in a MI winter.. but it always baffled me.. why it was two to three year old wood.. not the newest ...

one of the things most interesting moving from suburbia to 5 acres... is on how such a small lot.. even just 5 acres.. micro climates rule.. and what one plant is doing.. might be significantly different than the same.. just a hundred or 2 feet away ...

in my garden.. i have an 8 foot valley.. and the hosta down below .. leaf out a week or two later than those above... i figure cold air at night.. pools in the lower area.. keeping the soil colder to retard early growth.. the upside is.. it avoids frost/freeze damage on those plants ...

so.. jumping to a genetic explanation for differing oak leaf loss in spring.. might be a quantum leap ... or not.. who knows

ken

Thanks for the comments.

The ONLY reason I know this word is that we own the youngest oak tree in a neighborhood that is root-to-root in beautiful 40+ year-old live and other oak varieties. So there's an understandable concern about oak wilt that has had more than one of my neighbors asking what's wrong with our tree - it's the only one that looks like that (marcescent) this late into the season. Probably not enough variation within our neighborhood to attribute it to microclimate, so genetics and age are next likely suspects.

Shumardii is one of several oaks in which this trait is known to be strong, but it also hybridizes easily, which could help explain some variation - especially among natural stands. I'm GUESSING that it is also more pronounced in the juvenile trees - meaning I could tell the neighbors our tree will eventually out grow it. :-)

The following link provides a good non-academic overview.

Here is a link that might be useful: Why Do Oak Leaves Hold on Longer Than Other Leaves in the Fall?

As the article notes, certain species are prone to marcescense - Carpinteria and Carpinus to name a couple of others besides oaks. Robert Frost mentions this phenomenon in his poem 'Reluctance', which was the first place I encountered it! I always thought that these trees, rather than forming an incomplete abscission layer simply had a particularly thick one but that doesn't seem be suggested in anything that I read after this thread piqued my curiosity. Ken totally agree on the microclimates - it is amazing what a difference exists between different spots on the same property.

the best time to note city wide micros.. is forsythia bloom ...

one guys whole yard is covered in the blinding yellow.. and a block away... someone elses are just budding..

since there is nothing else blooming at the time.. in MI anyway ... its easy to spot ...

and i am just 2 miles from the megatropolis of tecumseh mi ... and mine will bloom one to two weeks later than in town [which is 8 blocks wide] ...

i think all the pavement and parking lots.. start retaining spring warmth .. so that nights soil temps dont get as cold... so they 'pop' a bit earlier ... because the soil warms faster ..... as compared to my garden ...

even across my 500 foot square garden.. the oaks drop their leaves as much as a week or two apart ...

go figure ...

ken

@formandfoliage: Enjoyed the related Frost poem. Thanks! It's in the public domain in the US, so have provided a link in case others are curious.

@ken_adrian: I've observed similar differences even around our relatively small city lot and agree that most variations in leaf coverage we see at any moment among the same type trees are likely explained by your points. The difference with our specific tree is not that it drops its leaves a few days or weeks after the other deciduous oaks, but that it holds them until the Live Oaks drop theirs in the spring. This additional 3 or 4 months of dead leaf retention seems to be a difference in behavior beyond what you've been speaking of in the more general case.

I made a foot search and found an older tree with the same marcescence in a cul-de-sac I rarely visit. It's actually not that far from us through the trees and over the rooftops as the squirrel runs, so could be our tree's parent. I can't tell one red from another this time of year, but will take a stab at it once things leaf out and see if any of the currently bare neighbors are also Shumardii.

Here is a link that might be useful: Reluctance by Robert Frost (1913)

This post was edited by bostedo on Wed, Feb 27, 13 at 17:50

I think your stuck with it. I think your right in that Shumards usually are not marcesant or at least not as bad as Q. buckleyi.

I've got a Shumard in my back yard that's relatively young. The time it holds its leaves seems to vary a good bit from year to year. I don't have a lot of historical data, but colder winters seem to make it drop its leaves earlier. It hung on to them until around late January this year.