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Editor's Picks

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The Global Conservation Consortium for Oak (GCCO) has...
Amy Byrne | Feb 17, 2020
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Hayrettin Karaca, an IOS member and one of Turkey's best-...
Roderick Cameron | Feb 10, 2020
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There are a growing number of unique hybrid selections that...
Ryan Russell | Feb 10, 2020

Plant Focus

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Quercus tarokoensis (local name 太鲁阁栎 tai lu ge li, "oak of Taroko") is a fairly unknown oak species, restricted to eastern Taiwan.

Cultivar Close-Up: Mighty Miniatures

Quercus palustris ‘Swamp Pygmy’

This selection of pin oak was found growing in a swampy area of Meeuwissen Nursery, Zundert, Netherlands. It was cultivated and sold by Bömer Nurseries, also of Zundert, Netherlands, and has since made its way to nurseries in the U.S. It is different from many other pin oak cultivars because of its small stature. An apparent genetic dwarf, ‘Swamp Pygmy’ remains a shrubby tree around 5 × 3 m (likely a little larger with age). Its foliage is typical for the species and can achieve nice fall color. No doubt a plant for the collector, this cultivar could fit well in small gardens a larger tree would outgrow. There are a few other diminutive pin oak cultivars such as ‘Isabel’ and ’Döring's Kompakt’.

Quercus palustris Swamp Pygmy
Quercus palustris ‘Swamp Pygmy’ © Milan Havils (www.havlis.cz)

Quercus robur ‘Tromp Dwarf’

This selection of English oak (or common oak) was first raised at the Arboretum Trompenburg, Rotterdam, Netherlands in 1979. It is a seedling of Q. robur ‘Cristata’ and was cultivated by the late Dick van Hoey Smith. ‘Tromp Dwarf’ is a very dense, slow growing, multi-stemmed plant eventually reaching 1.5 × 1 m. The leaves show an affinity to its ‘Cristata’ parentage, being somewhat twisted and congested on the stems. Even smaller in size than the above selection, ‘Tromp Dwarf’ could fit into nearly any size garden. There are a few newer selections of dwarf Q. robur such as ‘Blue Gnome’ and ‘Kobold’. These selections can occasionally be found in specialty nurseries.

Quercus robur Tromp Dwarf
Quercus robur ‘Tromp Dwarf’ in Arboretum Trompenburg © Arboretum Trompenburg

Quercus ilex ‘Ditha Jung‘

Keeping with the “mini-oak” theme, this cultivar of holly oak (holm oak) is by most accounts a miniature. In 1989, Gerhard Dönig made a collection of seed from a small evergreen shrub of Q. ilex near Lake Garda in north-central Italy. Originally two small-statured seedlings arose from that collection, but one ultimately survived and was named ‘Ditha Jung’. It was selected for its dwarf, pyramidal habit and tiny evergreen foliage (30 × 5 mm). At the time it was registered in 2011 (23 years of age), it had managed a size of only 85 cm tall × 25 cm wide. This selection is rare in the nursery trade but has been offered at a German nursery. Mr. Dönig named this selection after his mother-in-law, and the original plant is still growing at the Arboretum Altdorf, Germany. This is the only registered dwarf cultivar of Q. ilex, but another form is known to exist.

Quercus ilex Ditha Jung
Quercus ilex ‘Ditha Jung’ © Gerhard Dönig