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Plant Focus

Quercus xjackiana acorns
The hybrid of Q. alba and Q. bicolor

Hybrid Highlight: Quercus ×morehus Kellogg

Quercus ×morehus was initially called Abram’s oak by the author Albert Kellogg in his original 1863 description and was thought to be a unique species at the time (although his description was based on a single specimen). Current taxonomy designates this as a hybrid of Q. kelloggii and Q. wislizeni and is now known as the Oracle oak thanks to Willis Linn Jepson’s book The Silva of California, written in 1910.

Quercus xmorehus
Quercus ×morehus © Timothy Ives

While it is unclear exactly why Kellogg named this species Quercus morehus (also spelled moreha in some literature), it seems that the intention was to pay homage to the Biblical Oak of Moreh (moreh being a derivative of yarah meaning to teach or give direction, or one who is an oracle). Another way to put it would be “Abram’s oak of Moreh”, or Abram’s oak. The name Moreh can be applied to a hill, as well as an oak tree at Shechem where Abram (Abraham) stopped as he entered Canaan.    

Oracle oak Dirk
Oracle oak in winter, January 2019, Cleveland National Forest, Palomar Mountain, CA, with Quercus kelloggii on right and Q. wislizeni in the middle distance, right of center © Dirk Giseburt

Winter is the best opportunity to find Q. ×morehus in areas where the parent species overlap as the California black oak (Q. kelloggii) are deciduous and the Interior live oak (Q. wislizeni) are evergreen. Oracle oaks are semi-evergreen (or maybe more appropriately tardily-deciduous) and will generally have lost many of their leaves by mid-winter and will often have a yellow/brown appearance allowing them to stick out.

Quercus xmorehus
Quercus ×morehus showing partial leaf loss in winter © Lucas Dexter

I have read recent reports on the lack of seed production of this hybrid, but older accounts speak of better fruit production.

Quercus xganderi
Quercus ×ganderi (Q. kelloggii × agrifolia), near Santa Ysabel, San Diego County, CA, one of the hybrids often confused with Oracle oak © Dirk Giseburt

Interestingly, this oak is well known around the state, or at least the name Oracle oak is, and many claim to know of Oracle oaks in their area. On one of the recent Conference Pre-Tours, we saw an “Oracle” oak with the putative parentage of Q. kelloggii × parvula var. shrevei. A recent posting on a social media page touted an “Oracle” oak in southern California that had the supposed parentage of Q. kelloggii × chrysolepis. Another had the putative parentage of Q. kelloggii × agrifolia (which is the very similar Q. ×ganderi – see photo above). While none of these are the correct hybrid, it goes to show how well known this name is, even if people do not know or understand what parents are actually involved.  

Oracle oak leaf
Oracle oak leaf © Lucas Dexter
Oracle oak acorn
Oracle oak acorn © Lucas Dexter

There are websites such as iNaturalist (www.inaturalist.org) where you can log on and plot your findings and upload photos, and many have plotted Oracle oak sightings over a 600-mile range from Redding to San Diego. 

Oracle oak yellow and green
 A putative Quercus kelloggii × parvula var. shrevei, presented as Oracle oak during a 2018 Conference Pre-Tour © Ryan Russell  

The Oracle oak is no doubt an interesting plant to be admired by any who are lucky enough to see one or ponder what it can teach (or moreh) us.