But Portuguese oak shows little seasonal change

An oak I didn't see 'in the wild', but did encounter in Real Jardín Botánico de Madrid is the Portuguese Oak, Quercis faginea. The label on this cultivated specimen included the local common name for the species, Roble albar. Roble is the name given to all oaks in Spain, and albar means white.

This white oak is quite different to the American species traded under this name, Quercus alba, but it is classified in the same part of the genus - subgenus Quercus, section Quercus. It's distribution is not unlike the Pyrenees Oak I wrote about last week, although today it is considered to only occur in the Iberian Peninsula and not northern Africa (see below).

In the most recent issue (No. 33, 2022) of the journal of the International Oak Society, International Oaks, the distribution of Portuguese Oak in Portugal is documented, highlighting pockets of 'old-growth oaks'. Much of the original forest was cleared over the last three centuries for ship building and other construction, charcoal, tanning, firewood, and to provide land for agriculture.

The Portuguese Oak has rather stiff leaves which at first, like the Pyrenees Oak, are felty underneath. When mature, though, the leaves are almost hairless, so not soft and downy like those of the Pyrenees Oak. 

The International Oaks article describes the tree as 'marcescent' or 'semi-deciduous', meaning the some or all of the brown leaves persist on the tree through winter.

Once again we grow this species in Oak Lawn at Royal Botanic Gardens Melbourne, right next to the Pyrenees Oak. The difference between the two species in Melbourne when I returned from Madrid in mid-June was an abundance of green leaves on the Portguese Oak. So almost evergreen in Melbourne then, give or take an occasional brown leaf.

Ours is a far larger, and older, tree than the one in the Madrid botanic garden. The leaves on both trees are a little sinuous rather than deeply lobed, and the ripples can be sometimes a little pointy. This next branch is from our Melbourne tree.

Populations of a similar looking species called Quercus tlemcenensis, from the Atlas Mountains of northern Africa, were once treated as a subspecies (broteroi) of Quercus faginea. So the distribution of the Portuguese Oak has contracted back to being an Iberian 'endemic' (only known from this region).

None were present in Madrid or Melbourne in June but the acorns of the Portuguese Oak are described as distinctively elongate when compared to say your typical English Oak, often called 'cylindrical'. These acorns, along with those of the Ballota Oak (which I mentioned in passing last week), are fed to pigs to create one of those flavoursome Iberian ham. 

Another animal - in addition to the humans who eat the pigs who eat the acorns - to benefit from the Portuguese Oaks is the spider. In their natural habitats in Portugal, the trees support more species of locally endemic spiders than any other Iberian oaks it seems.

Real Jardín Botánico de Madrid