How to conduct a detailed analysis for Oaks (Genus Quercus)
Sometimes Quercus hybrids can be quite difficult to determine, but doing a detailed analysis can prove the parentage of an individual or reveal new information. Thankfully the only tools you'll need for this are a measurement device using millimeters and a macro lens (although a microscope makes this much easier). I recommend checking what measurements are actually useful for what you're IDing, as most of the time you won't need most of these factors. I recommend comparing this information to the pages on Flora of North America or similar regional databases.
Anyways, here's my list:
General:
Deciduous or evergreen
Number of trunks
Height
Trunk diameter (in inches) at 4.5'. This is called the Diameter Breast Height or DBH, not often used
Bark:
Color
Texture
Twigs:
Color
Diameter (mm)
Pubescence
Buds:
Color
Shape
Diameter (mm)
Pubescence
Length
Leaves:
Petiole color
Petiole length (mm)
Leaf shape
Leaf length and width (mm)
Base shape
Margin shape
Amount of lobes
Sinus depths (mm)
Secondary veins per side (often different from the number of lobes)
Apex shape
Lobe apex shape
Abaxial color
Abaxial pubescence (hair density, type, and number of rays)
Adaxial color
Adaxial pubescence (hair density, type, and number of rays)
Thickness
Acorns:
Sessile/pedunculate
Number of acorns per group
Cup shape
Cup depth (mm)
Cup width (mm)
Cup pubescence
How much of the nut the cap encases
Scale color
Scale shape
Scale pattern
Nut wall thickness
Nut shape
Nut length and diameter (mm)
Nut pubescence
Nut color
Apex shape
Scar diameter
I hope you found this useful and if you know of any other qualities useful for ID please comment them.
Comments
A few others that I've looked at before: bud length, leaf thickness (might need specialized equipment, but can also be approximated by feel/stiffness), attachment scar diameter on the acorn cap, lobe apex shape (might fit under margin shape)
Not sure if these are specifically helpful for Sect. quercus oaks, but I think generally all oaks would use similar features.
I was thinking about creating a big spreadsheet where you could plug in this information and it would spit out some kind of indication of overall fit for each species/hybrid within a subsection. But I don't know when I would find the time for that. We'll see.
Thanks, I'll go ahead and add those! Also I just realized the name of this might imply that it's for white oaks only so I'll go ahead and fix that.
I was also thinking about the spreadsheet thing but I don't have enough time to do that by myself unfortunately. It would be super useful though
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