Wednesday, February 1, 2012

Quercus...hemisphaerica?

More often than not, I find specimens (like Monday's Erica) while on a run, and I snap photos of them on a older version iPhone that is painfully slow and takes somewhat fuzzy pics.  Recently, on a run past Arlington Cemetery, I noticed these trees and decided to return with an actual real camera. 


The habit of the plant made me certain it was an oak, though I was surprised to see any evergreen oaks in our climate.  I had heard rumors that live oaks (Quercus virginiana) can survive up here but wasn't quite convinced this was that species.  (It should be noted that the use of virginiana as a species name doesn't literally mean of the state of Virginia, but simply of the colonies.  Canadensis is used for a similar purpose as well as occidentalis, which means 'western' and indeed the new world was west of Europe.)


Upon further look however, of photos of this plant and of Quercus virginiana, I became certain that they are not a match.  A quick look at my post on NYPAOS would illustrate how different the bark is on this species.  On Q. virginiana, the bark is corky and blocky, whereas this species has the shallowly fluted bark similar to a red oak (Quercus rubra). This was a great clue that perhaps this mystery species was in the red oak (or Loboatae) section of the genus.  After a bit of investigation, I'm tempted to identify this as Quercus hemisphaerica or laurel oak.  Everything I read on Dirr seems to help confirm this.  The plant is marginally hardy, loses its leaves around February (depending on the severity of the winter - and this one has been mild) and is generally a tough plant, used commonly as a street tree further south. 


Finally, as the common name implies, the leaves do look like laurel leaves.  I will have to watch this plant and take more pics when it forms acorns which should help confim the species. 





3 comments:

  1. I kind of thought the close ups looked like mountain laurel or Cherry laurel.

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  2. From your photo, the tree appears to be Quercus hemisphaerica (Darlington Oak) rather than Quercus laurifolia (Laurel Oak). I know this might sound confusing, but these are very closely related trees which are both in the red oak family. The Darlington Oak (Quercus hemisphaerica) is considered a subspecies of the Laurel Oak (Quercus laurifolia) by some, but the majority of botanists list them as separate species. Quercus laurifolia tends to remain evergreen until or unless the weather dictates and all of the leaves tend to fall off the tree symmetrically. But Quercus hemisphaerica tends to lose the upper most leaves of the tree first (similar to your picture) while retaining lower leaves until the new leaves grow in the spring.

    Q. laurifolia has more serrations on its leaves than Q. hemisphaerica does. Also, laurifolia flowers about 2 weeks earlier in the spring than hemisphaerica. Laurifolia is sold in lots of southern nurseries buy hemisphaerica is much harder to find. You can go to Darlington SC. (where the plant was first discovered) and find hemisphaerica growing wild in the wooded areas. Both trees are hardy to zone 6a and do well in northern Virginia.

    Quercus laurifolia (Laurel Oak) and Quercus virginiana zone 7a) (Live Oak) grow wild in southeastern Virginia and Quercus laurifolia can be found along the ocean all the way up to near New Jersey.

    Hope this helps
    thekingdomkeys

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  3. I also think it's hemisphaerica, because the leaves are pointed on the apical end. Can't really see a flat leaf in your closeup, but hemisphaerica 'tends' to have leaf bases that are rounded (obtuse), while laurifolia as leaf bases that are acute.

    I'm in Fairfax County and have three Q. virginianas in my yard which seem to be doing quite well.

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