Running a couple of unusual Mexican Oaks up the flagpole

Two unusual oaks today, from Geoff Bogle's Arboretum and originally from Mexico. There are between 400-450 species of Quercus (‘roughly 435’ according to a recent Scientific American report), mostly from temperate northern hemisphere (China, India, western Asia, Mediterranean and other parts of Europe) but also montane tropics in the Americas and south-east Asia.

The greatest diversity is in the Americas (with about 60% of species) and within that region, Mexico and Central America (with about 40%). China is also very well represented. 

But to Mexico today. I'll start with the species Allen Coombes (Curator of Scientific Collections in the Herbarium and Botanic Gardens at Benemérita Universidad Autónoma de Puebla, Mexico) described as his 'Tree of the Year' in the 2015 Yearbook of the International Dendrology Society.

It's the Loquat-leaf Oak, Quercus rysophylla. As Coobes points out, and confirmed for me by the alternate spellings in Geoff Bogles's list and what was I transcribed on the day, that species name is prone to misspellings.

Loquat-leaf Oak, with Lynda and Reg looking the other way

This is not one of the 71 oak species we grow in Melbourne Gardens (at least not yet), and not commonly grown in Australia. The only Australian plantings cited by Coombes are in Dunkeld, grown by well-known plant collector and grower Bill Funk, from acorns sourced from naturally growing material in Nuevo León. I can't be sure, but I think Geoff said got his plant material (acorns?) from Bill. Coombes does say that the species is not available through a few local nurseries so it may be growing in other gardens by now.

Now, Nuevo León is where the first material cultivated outside of Mexico was sourced, in the 1970s. We are in Sierra Madre Oriental, a mountain range in the north-east of Mexico, pretty much the only place where the Loquat-leaf Oak grows naturally. Its a tree of moderate to high altitudes (above 500 metres and up to 1700 metres above sea level). It's not uncommon there, but with fragmented populations still subject to logging. It grows with Linden/Lime (Tilia) and Sweet Gum (Liquidambar). 

The leaves of this tree are very unusual for an oak. The colour of the new growth is radiantly red, and even the mature leaves remain softer than most oaks - yes, a bit like a loquat.

It's a 'red oak', which means there are pointy bits on the edge of the leaves (unlike the rounded lobes of, say, the English Oak). Although many of the older leaves are almost entire - like a loquat. In the picture above you can see young leaves to the left with ragged edges.

As to those misspellings, the author of the name was an amateur botanist from Connecticut called Charles Weatherby, attempting to reflect its wrinkled leaf in the species epithet. Normally that would be transcribed as 'rhysophylla', from the Greek rhysos for wrinkled and phylla for leaf. But some reason, when Weatherby coined the name in 1926 he left out the first 'h' (as a Harvard student of literature, with a good knowledge of the classics, this was an odd and inexplicable error).

Later authors have helpfully but inappropriately changed the spelling to rhysophylla (as Geoff had done in his list), or branched out on their own with variations such as risophylla, rhizophylla (the spelling I made up when it was provided to me verbally) and rizophylla. We are obliged in this instance to stick with what Weatherby wrote, rysophylla.

By the way, neither of my two oaks had mature acorns on the day but I did find these few, I think immature, fruits on the Loquat-leaf Oak.

That common name, Loquat-leaf Oak, name needs no further explanation, but it also has a local Mexican name, Encino de Asta, which translates as the Flagpole Oak. Coombes suspects this is because it grows fast and straight.

That Mexican name, though, has also been used for the second of my Mexican oaks, Quercus candicans. It too is a red oak, as you can tell by the rather small pointy bits along the leaf edge again.

Flagpole Oak II, as we'll call it here, grows further south in Mexico, and at higher altitudes (above 1200 metres and up to 2700 metres), presumably seeking the cooler conditions oaks need to survive in the tropics. It was described by a French botanist on the Spanish-led Malaspina Expedition, Luis Née, in 1801.

I know a little about Luis Née, which I'll share with you. He was born in France but worked most of his life in, or for, Spain, establishing the botanic garden in Pamplona in 1784. Née joined the Malaspina expedition as an assistant to the Guatemalan (with Spanish parents) botanist Antonio Pineda, and together they collected in South and Central America, as well as elsewhere. Their journey including a stopover at Port Jackson in 1793, just five years after the British had established their penal colony in New South Wales.

Née was also sent material by other botanists associated with the expedition, in the end describing 16 new oak species, mostly Mexico and southern USA. Anyway, he must have been impressed by the leaves of this particular species, Flapole Oak II.

Don Teese showing me the undersurface of leaves on Flagpole Oak II

As you can see, the leaf is huge, more like a Fiddle Leaf Fig, at least from the top. No red new growth here but the large leaves are soft and white underneath. You can also see the curvaceous leaf stalks in this next picture.

We don't have this Flagpole Oak either in Melbourne Gardens. Well, again, not yet*. I must ask my colleague Peter Symes to run both through his climate suitability algorithm, to see if they'll tolerate the temperatures and rainfall we expect in Melbourne in, say, 2120 or thereabouts.

Flagpole Oak II, with Lynda, Reg and Don Teese to the left

Postscript (5 January 2021): As of November 2020, we now have a Quercus rysophylla planted in our Oak Lawn. It joins the Valley Oak from California as a replacement for the collapsed White Oak hybrid.