Australian Stalwarts and Newcomers
By James E. Henrich, Curator of Living Collections
The Arboretum is continually acquiring new species, creating an ever-evolving, dynamic living collection. Time, climate, environmental conditions, quality of maintenance, to name a few, selectively eliminate those not adapted to our conditions. The selection process yields strong, average and poor performers from the remaining plants.
Let’s look at some examples from the Australia collection which is ideal for this discussion. Why? Our species come from nearly every territory in Australia, ranging from the southwestern Mediterranean zone to seasonally dry forests of Queensland and New South Wales. The species are highly adaptable and well suited to the climate of Southern California. An additional advantage is drought tolerance, a trait that is characteristic of plants from Mediterranean climate zones.
One goal for the living collection is continual diversification while, at the same time, respecting the value of stalwart species. Tasmanian blue gum (Eucalyptus globulus) is a good example of the latter. Our oldest specimen dates to the early 1860s. The number of specimens of Tasmanian blue gum has declined due to old age, pests or pathogens, making it is a prime candidate for re-introduction to the collection. This is done to establish a new generation, a practice similar to the management plan for our Engelmann oak grove.
Species recently planted in the landscape include: red-flowering gum (Eucalyptus ficifolia [now Corymbia]); Forrest’s marlock (E. forrestiana) and coral gum (E. torquata). Specimens of each exist in the landscape already, but some are aging or not performing well. Each has stunning characteristics that make them valuable. Red-flowering gum has extremely variable flower color including white, pink, orange and red. Forrest’s marlock was acquired and propagated unsuccessfully ten times between 1949 and 1986 until one 1986 accession was established successfully, with one more individual this year. It has stunning fuchsia-colored ovaries and bright yellow stamens. Coral gum is a small to medium-size tree with coral-pink stamens and tangerine to red ovaries; it can flower in two years from seed.
The first chart below features Eucalyptus species new to our current living inventory. Of note are these species: Nundroo gum (Eucalyptus calcareana) with smooth bark and ribbons of cream, gray and orange-tan; Bendemeer white gum (E. elliptica) with striking chalk-white bark; and Webster’s mallee (E. websteriana) with beautiful cinnamon-red curling bark and cordate leaves. Seeds of these species will be put into production in the near future and plants will begin appearing in the landscape in the next year or two. For an expanded version of the species discussed in this article and more, see our web site.
James E. Henrich is Curator of Living Collections at the Arboretum.
Newcomers: Eucalyptus species
|Scientific Name||Common Name||Distinguishing Trait|
|Eucalyptus approximans||Barren Mountain mallee||Steely gray-green or white bark|
|Eucalyptus arachnaea||black-stemmed mallee||Multi-trunked tree with black bark|
|Eucalyptus calcareana||Nundroo gum||Smooth bark with ribbons of cream, gray and orange-tan|
|Eucalyptus cernua||red-flowered moort||Red flowers, shrub|
|Eucalyptus deanei||Deane’s gum||New bark bright yellow|
|Eucalyptus delegatensis||alpine ash||Upper bark whitish to yellow-gray|
|Eucalyptus elliptica||Bendemeer white gum||Bark striking chalk-white|
|Eucalyptus kartzoffiana||Araluen gum||Juvenile leaves are intense bluish color|
|Eucalyptus lesouefii||Goldfield’s blackbutt||Distinctive black basal “stocking” of bark|
|Eucalyptus ligustrina||privet-leaved stringybark||Bark gray to red-brown|
|Eucalyptus michaeliana||Hillgrove gum||Eye-catching mottled bark|
|Eucalyptus microcarpa||inland gray box||Typical box-type bark|
|Eucalyptus paliformis||Wadbilliga ash||Bark gray to olive green with chalk white|
|Eucalyptus pilularis||blackbutt||Rough fibrous bark|
|Eucalyptus rudis||flooded gum||Rough bark on trunk and smooth gray bark on branches|
|Eucalyptus sieberi||coast ash||Bark of young trees flaky, orange-brown|
|Eucalyptus sturgissiana||Ettrema mallee||Restricted to sandstone plateaus in NSW|
|Eucalyptus utilis||coastal moort||Large white flowers, restricted to south coast of Western Australia|
|Eucalyptus websteriana||Webster’s mallee||Beautiful cinnamon-red curling bark and heart-shaped leaves|
Our Australian Stalwarts
We have placed emphasis on rejuvenating the Australian collection because of its long-standing diversity and historical significance among public collections. Let’s look at this collection for a comparison of species that have persisted for many decades, ones that have been added recently and those that are new to the collection. The table below features a selection of species that have thrived for decades, diminished in number of specimens and new additions. It contains scientific name, common name, year accessioned and planted (persisted in landscape), and year accessioned & short lived (either in the landscape or the nursery). The fourth column contains years for accessions that never left the nursery or specimens that lived only very briefly in the landscape—see comment below table for reasons. It becomes apparent that desirability is often a factor driving the frequency of acquisition exemplified by E. ficifolia, E. macrocarpa, E. torquata, X. quadrangulata.
|Name||Common Name||Acc. & planted||Acc. & short lived*|
|Acacia glaucoptera||Clay wattle||1986s, 1991c, 1999p, 2002p||1974s, 1978c|
|Angophora costata||Smooth-barked apple||1953s, 1954s, 1964s||1969s, 1950s, 1959s, 1978s, 1985p|
|Callistemon citrinus ‘Jeffers’||Bottlebrush||2009p||None|
|Callistemon viminalis ‘Harkness’||Bottlebrush||1968c, 1972p, 1977p||1968c|
|Eucalyptus diversicolor||Karri gum||1954p, 2004p||1951s, 1953s, 1954s, 1954s, 1958s, 1967s|
|Eucalyptus ficifolia (Corymbia ficifolia)||Red-flowering gum||1949s, 1954s, 1960s, 1967p, 1971p, 1983p 1988s, 1997p, 2002p, 2002p, 2006p||1948s, 1949s, 1951s, 1953s, 1954s, 1956s, 1957p, 1957p, 1958p, 1960s, 1967p, 1969p, 1970p, 1970s, 1970p|
|Eucalyptus globulus||Tasmanian blue gum||1948p, 1955s, 1999s||1950p|
|Eucalyptus gunnii||Cider gum||1966s, 1979s||1950s, 1953s, 1956p, 1971s|
|Eucalyptus macrocarpa||Coolgardie rose||1957s, 1985s, 1986s, 2005s, 2006p||1949p, 1949s, 1949s, 1953s, 1956s, 1957s, 1958s, 1959s, 1969s|
|Eucalyptus torquata||Coral gum||1950s, 1963s, 1969s, 1986p, 1986s, 1986s, 1997p||1949s, 1950s, 1959s, 1963s, 1965s, 1980p|
|Geijera parviflora||Australian willow||1951s, 1955s, 1970p, 1981p, 1988p||1980p|
|Melaleuca linariifolia||Flax-leaf paperbark||1954s, 1959s, 1997c||1951s, 1955p, 1960s, 1965s|
|Xanthorrhoea quadrangulata||Grass tree||1951s, 1971s, 1972p, 1981p, 1987s, 1989s, 1996s, 1998p||1960s, 1975s, 1975s, 1975s, 1976s, 1980s|
Legend: c=cutting, p=plant; s=seed
Alive in the most recent inventory
Species planted in 2016
*=did not get planted in the landscape because of the following: not propagated; failed to germinate/root; died in the nursery; remained in the nursery too long resulting in a deformed specimen; frost damage; poor care; hit by a truck
1948 is the year LASCA was incorporated
1949 is the first year new germplasm was acquired, accessioned, planted