Eucalyptus leucoxylon F. Muell.

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Credits

Article from New Trees, Ross Bayton & John Grimshaw

Recommended citation
'Eucalyptus leucoxylon' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/eucalyptus/eucalyptus-leucoxylon/). Accessed 2021-09-22.

Common Names

  • Yellow Gum

Glossary

key
(of fruit) Vernacular English term for winged samaras (as in e.g. Acer Fraxinus Ulmus)
subspecies
(subsp.) Taxonomic rank for a group of organisms showing the principal characters of a species but with significant definable morphological differentiation. A subspecies occurs in populations that can occupy a distinct geographical range or habitat.

References

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Credits

Article from New Trees, Ross Bayton & John Grimshaw

Recommended citation
'Eucalyptus leucoxylon' from the website Trees and Shrubs Online (treesandshrubsonline.org/articles/eucalyptus/eucalyptus-leucoxylon/). Accessed 2021-09-22.

Only three of the six subspecies of Eucalyptus leucoxylon appear to be in cultivation in the temperate northern hemisphere. The key below, modified from those of Rule (1991, 1998), includes all recognised subspecies. A seventh subspecies was recently elevated to specific status as E. petiolaris (Boland) K. Rule (Rule 1992).


subsp. leucoxylon

Tree 10–30 m. Bark rough to 2 m, smooth above, grey or reddish brown or yellow. Juvenile leaves sessile, broadly lanceolate to ovate, dull green. Adult leaves dull green to blue-green, 9–13 × 1.3–2.5 cm, narrowly lanceolate, not falcate, lateral veins just visible, margins entire, apex acute; petiole flattened or channelled, 1–2 cm long. Inflorescences solitary, axillary; umbellasters with three flowers. Flower buds ovoid or fusiform; hypanthium 0.5–0.7 cm wide; stamens white, cream, pink or red. Capsule ovoid to subglobose, 0.7–1.4 × 0.8–1.3 cm; valves slightly inserted. Chippendale 1988. Distribution AUSTRALIA: South Australia (Fleurieu Peninsula, Kangaroo Is.). Habitat Open forest. USDA Hardiness Zone 9. Conservation status Not evaluated.

Subsp. leucoxylon is very rare in cultivation in our area. It was attempted at Logan in the 1990s but has not survived there (Royal Botanic Garden Edinburgh 2007–2008).

1a.

Wax present on any of the following structures: juvenile leaves, branchlets, flower buds, fruits

2

1b.

Wax absent from all structures

3

2a.

Floral pedicels 15–27 mm long; flowers cream-white; Australia (Victoria: Bellarine Peninsula)

subsp. bellarinensis Rule

2b.

Floral pedicels 3–8 mm long; flowers cream-white; Australia (southeastern South Australia, western Victoria)

subsp. pruinosa (Miq.) Boland

3a.

Juvenile leaves often connate; flowers cream-white; Australia (Victoria: Brisbane Ranges)

subsp. connata Rule

3b.

Juvenile leaves never connate

4

4a.

Floral pedicels 3–7 mm long; flowers pink-red; dried membrane covering capsule mouth present; Australia (southeastern South Australia, western Victoria)

subsp. stephaniae Rule

4b.

Floral pedicels 8–30 mm long; dried membrane absent

5

5a.

Adult leaves > 2.5 cm wide; flowers cream-white to pink or red; fruits 12–16 × 10–15 mm; Australia (extreme southeastern South Australia)

subsp. megalocarpa Boland

5b.

Adult leaves < 2.5 cm wide; flowers cream-white to pink; fruits 9–13 × 7–10 mm; Australia (South Australia: Fleurieu Peninsula, Kangaroo Is.)

subsp. leucoxylon

 


subsp. megalocarpa Boland

As the name suggests, this subspecies has larger fruits than subsp. leucoxylon, but also larger leaves (see key above). Chippendale 1988. Distribution AUSTRALIA: South Australia (extreme southeast). Habitat Calcareous soils. USDA Hardiness Zone 9. Conservation status Not evaluated. Illustration NT345.

As the only red-flowered Eucalyptus to show any hardiness in northern Europe, E. leucoxylon subsp. megalocarpa (sometimes found in horticultural literature as E. leucoxylon ‘Rosea’) excites considerable interest. There are a handful of small trees in southern England, the most notable being the 4 m specimen in the Chelsea Physic Garden, London, which flowers prolifically. At Lamberhurst in Kent, Graham Blunt has a small plant of 160 cm that flowers well in a sheltered site. There is an 8 m specimen at Tresco Abbey (TROBI), but the largest trees in the mainland United Kingdom are at Logan, where there are three rather unhappy specimens of about 6 m. If sufficiently mild and sheltered conditions cannot be provided to cultivate this taxon outdoors, it can be grown in a large container and given minimal frost-protection under cover in winter. Seedlings will flower when 1 m high, so its value as a flowering container plant is potentially considerable. The bark is reddish, peeling to reveal a paler underlayer, and the green leaves are narrow and somewhat contorted.


subsp. pruinosa (Miq.) Boland

This subspecies is notable for the waxy deposits that may occur on the juvenile leaves, branchlets, flower buds and fruits. Chippendale 1988. Distribution AUSTRALIA: South Australia (southeast), Victoria (central and west). Habitat Woodland with clay or sandy soils. USDA Hardiness Zone (9–)10. Conservation status Not evaluated.

This taxon is in cultivation but is even less hardy than subsp. megalocarpa, having been very seriously damaged by –5 ºC in Cornwall (J. Purse, pers. comm. 2007).