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Back in 1767 a British gentleman named Alexander Dalrymple theorised on the existence of a Terra Australis Incognita to the south of New Guinea, and suggested a route to the Unknown based on the old maps done by Luis Váez de Torres, the Spaniard that a century earlier could have discovered Terra Australis... twice. Three years after the theory Sir Joseph Banks was onboard Captain Cook's Endeavour towards Botany Bay, which would start the practical discovery of Australian flora and soon of a new country for the British Empire. Eucalyptus country.
E. dalrympleana: four subspecies
- E. dalrympleana ssp. dalrympleana - Mainly present along the Great Dividing Range in both Victoria and Southern NSW
- E. dalrympleana ssp. heptantha - 7 flowered mountain white gum from Northern NSW
- E. dalrympleana ssp. 'Tasmania' - In mid to high elevations in the Highlands of the Central Plateau
- E. dalrympleana ssp. 'Alpine' - Small to medium sized tree growing in restricted populations found above 1200 m altitude in the Victorian Alps
This opens a door for more confusion, since seed of white gum grown overseas until well beyond 1920 could have been of any of these species, but only E. viminalis was known. Which can easily make local races derived from old trees before foresters understood the importance of good seed collection methods and good seed provenance records also suspicious of having some Mountain Gum blood in them.
E. dalrympleana: hybrids and clines
Indeed hybridism is relatively common event in the natural habitat of the White Mountain Gum, and the example of Eucalyptus viminalis x dalrympleana has been found with relative frequency in those areas where both species grow together (which is not so rare, given the high degree of overlapping habitats for both eucalypts, also both within Subgenus Symphyomyrtus and Series Viminales, close relatives).
This was initially suggested to explain variation among seed provenances from mainland Australia by Mendonza as early as 1968, since a narrow 50 m belt of intermediate forms where populations of both species occupy the same habitat later was found. It was later confirmed in forestry trials in Argentina.
A further milestone was established in 1980 by Philips & Reid, who examined a transect of 120 km from sea level to the Highlands in Tasmania and observeed clinal variation in this natural Eucalyptus vimdal Complex, identifying a continuum of intermediate forms from thin lanceolate juvenile leaves of E. viminalis in coastal areas to cordate juvenile leaves typical of E. dalrympleana in the Central Plateau and concluding intermediate specimens were the most common type. Variation for flower buds and seed capsules in what regards to their sizes and numbers was not as consistent as juvenile foliage variation in a geographic sense.
This can confirm the prepared observer if a clear case of any subspecies of E. dalrympleana or any subspecies of E. viminalis is present, or if something else. Unless your trees have something to do with France!
The results of this effort of breeding, selection, domestication and controlled hybridisation yielded in the 1980's a new gene pool with echoes to the natural E. vimdal: Eucalyptus gunnii x dalrympleana, the E. gundal. Frost tolerant in the range of -10 to -15ºC, select clones of this hybrid strain can yield 20 to 25 m3 of timber per hectare and year, which makes it an interesting safe option for the colder part of ATL1 zones, albeit a bit risky for timber production ventures in ATL2 zones except in their milder part. Comparable to some extent in this sense to other cold hardy eucalypts commonly grown for timber production in Northwestern Spain, as E. macarthurii and E. nitens.
After the devastating effects of unusual heavy frosts as the ones affecting the Midi-Pyrénées in 1985, reaching absolute minima lower than -20ºC, the focus has been put on further selection of cold hardy strains among the E. gunnii side of the genetic pool (more than 600 clones) and further planting has taken place in the last 10 years.
E. dalrympleana: the Spanish case
Mendonza, L. A. (1974) Ensayos de procedencias de Eucalyptus camaldulensis Dehn, y E. viminalis Labill. en el norte de la provincia de Buenos Aires. IDIA Suplemento Forestal 1973-74, 53-60.
Philips, R. L. & Reid, J. B. (1980) Clinal variation between Eucalyptus viminalis Labill. and E. dalrympleana Maiden. Australian Journal of Botany 28, 329-342.
Marien, J.N. & Thibout, H. (1982) Les Eucalyptus en France. Annales de Recherches Sylvicoles 1981, AFOCEL, Association Forêt-Cellulose, 34 – 72
Griffin, A. R., Burguess, I. P., & Wolf, L. (1988) Patterns of natural and manipulated hybridisation in the genus Eucalyptus L'Hérit. - a review. Australian Journal of Botany 36, 41-66.
Ruíz, J. (1993) Selection and vegetative propagation of Eucalyptus dalrympleana Maiden. Proceedings of IUFRO-AFOCEL meeting: Mass Production Technology for Genetically Improved Fast Growing Forest Tree Species. Bordeaux 14-18/september/1992. Vol II pp: 277-283
Nguyen, The N. (2003) Présentation générale de l'Eucalyptus. Lettre d'information semestrielle Eucalyptus. Fiche Nº1. AFOCEL, Association Forêt Cellulose. [PDF]
Melun, F. & Nguyen, The N. (2005) Fiches Clonales: Eucalyptus gundal (E. gunnii x dalrympleana). AFOCEL, Association Forêt Cellulose. [PDF]
Purse, J. (2005) Eucalyptus species with potential for biomass in the British Isles. PrimaBio, Eucalyptus Specialists.
Nicolle, D. (2006) Eucalyptus of Victoria and Tasmania. Bloomings Books. Melbourne.
An intrepid plantsman photographs what is possibly the northernmost flowering Eucalyptus in the world. A blooming E. dalrympleana... in the fjords of Norway!
Northernmost flowering Eucalyptus: E. dalrympleana at 61ºN
We started at Dalrymple and jumped to Dalrymple-Hay talking about eucalypts today, so the proper thing is jumping now from Dalrymple-Hay to Hay to end up this Eucalyptus story. By Gum!