Cold hardy Eucalyptus hybrids... in the Danish Fjords!

Identifying Mystery Eucalyptus: The case of E. gunnii x nitens hybrids... in Denmark!

Gustavo Iglesias Trabado
GIT Forestry Consulting - Consultoría y Servicios de Ingeniería Agroforestal - www.git-forestry.com - EUCALYPTOLOGICS

We have previously showed you around here different cases of "odd eucalypts" growing in different parts of the world. First, the case of our friend Ian Barclay at the Desert Northwest finding a new eucalypt hybrid (Eucalyptus crenulata x nitens) growing among his ornamental plant stock. Then, some stories about hybrid E. gundal (Eucalyptus gunnii x dalrympleana) developed in France for forestry purposes. And some more blabla about Eucalyptus globulus x nitens, another potentially interesting hybrid choice for timber production.

Today we bring you some more about eucalypt hybrids. In this case, a type with some interest for those growing the ubiquitous Australian trees in the boundaries of their tolerance to cold. From Denmark, after enduring 8 winters, and thanks to Martin Reimers, we take a peek at Eucalyptus gunnii x nitens ... in two botanical plates!

Fig. 1: Botanical assessment of photographic samples leading to the identification of Martin Reimers' mystery Eucalyptus growing in the Northern shores of the Flensburg Fjord, Denmark, as a hybrid Eucalyptus gunnii x nitens. (Click the image to enlarge, 1280 x 1024 pix)

Product of the viable cross of two relatively closely related eucalypt taxa (both E. gunnii and E. nitens belong to subgenus Symphyomyrtus, Section Maidenaria, and differ just as part of Series Orbiculares and Series Globulares respectively, so they are somewhat "close cousins") , this particular interserial hybrid combination would be very unlikely without human intervention, since each species has its habitat at one side of the Bass Strait.

Fig. 2: Complementary botanical assessment of E. gunnii x nitens depicting the juvenile organs of both parent species and the hybrid cross. (Click image to enlarge, 1024 x 768 px).

Interestingly, Martin's tree shows some of the well desired effects of heterosis, and of a lucky combination of inherited good form, fast growth and cold hardiness. Precisely, if at some point we hinted that E. globulus x nitens could be of interest for some addition of cold hardiness to a benchmark species for short rotation timber plantations, this time the addition comes "on the other side of the frost spectrum".

Not in vain, fast growing E. nitens, a relatively cold hardy eucalypt species for temperate atlantic climates, able to tolerate a good number of frost events each winter but not extremely well adapted to harsh winters much beyond USDA Hardiness Zone 8a has, in this case, crossed with one of the cold hardiest eucalypts, the Tasmanian Cider Gum, able to survive in USDA Zone 7a. A promising sign for its, by now, good performance in an area of the world you would not instantly associate to the Australian trees.

Some Interesting Literature...

Listed below, some relevant bibliographic sources for cases like this, which could give the reader some insight on the mechanisms that made hybrid Eucalyptus trees like Martin's possible, and beyond possible, understandable. Reasons enough for compliments to be always sent to the Eucalyptus of France and Tasmania.

Cauvin B, Potts BM & Potts WC (1987). Eucalyptus: Hybridation artificielle - barrieres et hérédité des caracteres. Annales de Recherches Silvicoles 1986, AFOCEL, Paris. pp. 255-303.

Tibbits WN, & Reid JB (1987). Frost resistance in Eucalyptus nitens (Deane & Maiden) Maiden: genetic and seasonal aspects of variation. Australian Forest Research, 17 (1), 29-47 DOI: 0004-914X

Tibbits WN & Reid JB (1987). Frost Resistance in Eucalyptus nitens (Deane & Maiden) Maiden: Physiological Aspects of Hardiness. Australian Journal of Botany, 35 (3), 235-250. DOI: 10.1071/BT9870235

Griffin AR, Burgess IP & Wolf L (1988). Patterns of Natural and Manipulated Hybridisation in the Genus Eucalyptus L'Hérit. A Review. Australian Journal of Botany, 36 (1). DOI: 10.1071/BT9880041

Tibbits WN (1988). Germination and Morphology of Progeny From Controlled Pollinations of Eucalyptus nitens (Deane & Maiden) Maiden. Australian Journal of Botany, 36 (6). DOI: 10.1071/BT9880677

Tibbits WN (1989). Controlled Pollination Studies with Shining Gum (Eucalyptus nitens (Deane & Maiden) Maiden). Forestry, 62 (2), 111-126. DOI: 10.1093/forestry/62.2.111

Tibbits WN, Potts BM & Savva, MH (1991). Inheritance of freezing resistance in interspecific F1 hybrids of Eucalyptus. Theoretical and Applied Genetics, 83 (1). DOI: 10.1007/BF00229235

Bookmark this Interesting Link...

Besides growing several cold hardy Eucalyptus species with good potential for survival in the Eastern coast of Jutland, our fellow forester Martin Reimers has started to put together a wonderful database of performance for recently cultivated Eucalyptus all over Denmark.

www.eucalyptus.dk = Eukalyptus i Danmark = The database of Eucalyptus Cultivation in Denmark

Besides a growing amount of information on the history of Eucalyptus cultivation in Denmark, at www.eukalyptus.dk you can find fine photographic examples of E. gunnii (Cider Gum), E. gunnii x nitens, E. perriniana (Spinning Gum), E. dalrympleana (Mountain White Gum), E. pauciflora ssp. debeuzevillei (Jounama Snow Gum), E. pauciflora (White Sallee), E. nitens (Shining Gum), E. urnigera (Urn Fruited Gum) E. rubida (Candlebark), E. barberi (Barber's Gum), E. coccifera (Tasmanian Snow Gum), E. johnstonii (Tasmanian Yellow Gum), E. subcrenulata (Alpine Yellow Gum) and E. delegatensis (Alpine Ash) including detailed records of their cultivation and behaviour in such an apparently impossible location as the fjords, plains and islands of Denmark.

Some of these grow in the grounds of tree famous places as Copenhagen's Botanical Garden , recent receiver of Eucalyptus wedding gifts of Australia to Crown Princes Frederik and Mary; or as Hørsholm Arboretum, the largest collection of trees and shrubs in Denmark. But many do thrive also in the gardens of adventurous horticulturalists and private plant collectors scattered over the country, proving that at least the cold hardiest species within the genus can survive and bloom in yet another piece of Scandinavia.

Also in EUCALYPTOLOGICS... THE EUCALYPTUS OF THE FJORDS

Northernmost flowering Eucalyptus: E. dalrympleana at 61ºN in the Norwegian Fjords

Visit Frank Diron's Little Australia growing at Fanø Island in Denmark!

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© 2007-2009 Gustavo Iglesias Trabado. Please contact us if you want to use all or part of this text and photography elsewhere. We like to share, but we do not like rudeness.

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Eucalyptus flowers: E. nitens & E. globulus in bloom. Bees and Eucalyptus Hybrids.

Phenology of E. globulus and E. nitens in Galicia (Northwestern Spain)

Gustavo Iglesias Trabado
GIT Forestry Consulting - Consultoría y Servicios de Ingeniería Agroforestal - www.git-forestry.com - EUCALYPTOLOGICS

We have already seen some previous example of eucalypts blooming. Today we will see some more!

Shining Gum: Eucalyptus nitens flowers

Fig. 1: Examples of flower buds, blooms and infrutescences in Eucalyptus nitens growing in Galicia (NW Spain)

Widely introduced into commercial scale plantings in Galicia as a frost hardy alternative to E. globulus of the inland tablelands and ranges, E. nitens most commonly appears at altitudes between 400 and 900 m, growing in a variety of soil types and site conditions.

Its fast growth, small flower size (clusters around 1 cm), relatively delayed maturation age compared to other species and loss of basal branches when planted in timber stands can make spotting its blooms a difficult task without using binoculars. We have observed it blooming from late April well into July, but some variation in these phenologic ranges can happen every year depending on climatic tendences and some variation does occur also at different altitudes.

Tasmanian Blue Gum: Eucalyptus globulus ssp. globulus flowers

Fig. 2: Examples of flower buds and blooms of Eucalyptus globulus ssp. globulus growing in Galicia (NW Spain)

The classical species in the Atlantic coasts of Iberia (from Portugal to France), introduced in half the 19th century and widely planted in the milder coastal climates since mid 20th century, E. globulus ssp. globulus normally appears at altitudes between 0 and 500 m, also in a wide variety of soils and site conditions.

Spotting trees in bloom for this species is easy: it is one of the eucalypts with big flowers (3 to 7 cm diameter when blooming) and it does so profusely, covering the crowns with easily visible silvery white spots by the right time of the year and causing pollinator frenziness due to big amounts of nectar, which, keep me the secret, is also accessible to human beings and tastes certainly sweet. We have observed it blooming during winter and spring, from as early as late November to as late as the last weeks of May, with noticeable variation depending on tree age, microclimatic conditions and yearly climatic tendence making these extremes expand or contract depending on the year.

A jump ahead of seven steps: Eucalyptus "globens" or Eucalyptus "nitobulus"

For the sake of brevity (Bonum, si breve, bis bonum), after jumping from flower to flower "bee style", we jump ahead overcoming taxomomic, phisiologic, phenologic barriers, a bit more ahead overcoming seed collection, extraction and germination, a bit more ahead overcoming plant screening... et voilà!

Fig. 3: Example of Eucalyptus forestry species hybridisation: hybrid of E. globulus and E. nitens (E. nitens x globulus)

One of these days we will describe each small previous jump, and proceed further to yet another complex process: mass vegetative propagation!

The main driver should always be "Eucalyptus Heterosis can be exploited".

or, in the funny way...


Heteroid Eucalyptus Yields: Breed Elite Eucalypts!
(HEY BEE!)

GIT's Eucalyptology Topics

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© 2007 Gustavo Iglesias Trabado. Please contact us if you want to use all or part of this text and photography elsewhere. We like to share, but we do not like rudeness.

Click to Read Full Story...

Click to Display Summary only...