Log in

Editor's Picks

Group photos Texas OODs
Five days of oaking in the Lone Star State.
Roderick Cameron | Oct 21, 2023
Tour Participants on Fiddler Peak
An account of the Tour guided by Sean Hogan
Website Editor | Oct 19, 2023
Quercus pacifica
An collection specializing in native Californian oaks
Christina Varnava | Oct 18, 2023

Plant Focus

A small but mature Alabama sandstone oak producing acorns © Patrick Thompson
A Critically Endangered dwarf oak 

Mysterious Hansen Name Unveiled

In some oak databases one can find a few oak names described by a certain Hansen. And in every instance there is no link to a publication whatsoever. The most common cases are Q. greeneana, Q. patula, Q. rineharticena and Q. viridis. First I thought I might find something by searching for Swedish or German botanists, but I found nothing, although I was moving in the right direction (see below).

While browsing for Q. garryana Douglas ex Hook. on the invaluable website http://plants.jstor.org, I saw a herbarium specimen named Q. garryana Dougl. [sic],  but with a second label: Q. greeneana Hans. (leg. Georg Hansen). This label led me to a work written by Georg Hansen called the “Flora of the Sequoia Gigantea Region”. In this work Hansen describes some oak specimens: Q. greeneana, Q. patula, Q. ×dubia, Q. rinehartiana (not rineharticena), Q.×viridis, Q. ×morehus nothovar. nobilis and Q. chrysolepis var. mira.


Quercus greeneana, Quercus patula are synonyms of Quercus garryana Douglas ex Hook. var. garryana. Quercus viridis and Quercus ×morehus nothovar. nobilis are synonyms of Quercus morehus Kellog. Quercus

Quercus jacobi R.Br.ter and Q. garryana Douglas ex Hook.

chrysolepis var. mira could well be a synonym of Quercus chrysolepis Liebm. Quercus ×dubia (= Q. keloggii x Q. rhinehartiana) and Quercus rinehartiana are still unresolved. But Hansen wrote about Q. rinehartiana: “Species near to Kelloggii, but distinct in its lanate foliage, shoots and acorns.” Jepson commemorated Hansen in Quercus chrysolepis f. hansenii Jeps., (1909) and in Quercus chrysolepis var. hansenii (Jeps.) Jeps., (1923). A lot of other genera have the specific epithet hansenii.

Keen plantsman

The German born plantsman is also known for his fine drawings in Greene‘s” Illustrations of West American Oaks”. He wrote “The Orchid Hybrids: Enumeration and Classification of All Hybrids of Orchids”, published in 1895. W.L. Jepson wrote about the life and work of this remarkable man in Madroño in an article named THE BOTANICAL EXPLORERS OF CALIFORNIA part III (Madroño, Vol. 1, No. 12 (September, 1928), pp. 183-185).


Click on the images to view high resolution files

Quercus garryana Douglas ex Hook. [as Quercus jacobi R. Br.ter] Quercus gilberti Greene
Quercus macdonaldi Greene Quercus turbinella Greene