Arboreta, Patience, & Australian Trees

If you want to learn the meaning – that is, the beauty – of patience, visit a botanical garden or arboretum. I recently had the opportunity to do so in Arcadia, where the Los Angeles County Arboretum is located.
Arboretums and botanical gardens often consist of plant and tree collections that are grouped by continent. In other words, you will find North American, South American, European, Asian and Australian sections in a typical botanical garden.
In the arboretum in Arcadia, after losing track of time, I suddenly realized I had spent over an hour wandering in the Australian section. Although there were no koala sightings, I was privileged to glimpse several special species of flora that I had either never seen before or, if I had, were not nearly as impressive as they were here.
One of the most popular shrub selections of the last decade or two has been dwarf bottlebrush (Callistemon citrinus ‘Little John’).
If you read the literature on this plant, you will see it touted as a slow-growing, compact shrub that does not exceed 3 feet in height. Yet in Arcadia there was a specimen that had reached a height of 7 feet. I could not help wondering if this very plant was the first of its kind to be planted in Southern California since arboretums are often chosen as test locations for new plant varieties. For all I know, this specimen could have been growing here for more than 20 years.
‘Little John’ bottlebrush is appealing because of its bristled scarlet flowers that are nearly always in bloom, with hummingbirds hovering around them, and because of its appropriately contrasting soft, blue-green foliage.
I had never seen a ‘Little John’ more than 3 feet tall, but this did not mean it lacked the potential to grow twice that size, given the proper conditions for growth. An arboretum provides optimum conditions for plants for one simple reason: ample space is provided for them to develop.
In our tightly planted and hemmed-in gardens – where an overabundance of plants are crammed together for instant effect, touching one another or flush against building facades – it is difficult for plants to grow to their maximum potential because of root competition, as well as inhibited shade or uncomfortable proximity to walls or structures.
Two Australian eucalyptus species I happened upon, although not in bloom, struck me as highly suitable for bouquet supplementation due to their red stems and vivid foliage. Foliage of selected eucalyptus species, especially those with powder-blue leaves such as silver dollar eucalyptus (Eucalyptus cinerea) and silver mountain gum (Eucalyptus pulverulenta ‘Baby Blue’), may last up to six months in dry arrangements.
At the arboretum, there is a silvery blue specimen labeled blue-leaved mallee (Eucalyptus cyanophylla), as well as a so-called coarse-leaved mallee (Eucalyptus grossa), with attractive blue-green, egg-shaped foliage.
If you are a eucalyptus connoisseur, you know that mallees are shrubby eucalypts with multiple trunks that grow up from lignotubers. Lignotubers are starch-enriched, semi-underground, potatolike structures that allow mallees to sustain themselves through periods of stress and to re-establish themselves after being burned to the ground in fires that are part and parcel of scrubby Mediterranean and chaparral forest ecology. When favorable conditions for growth resume, lignotubers sprout new shoots from latent buds.
Speaking of ability to survive stress, an examination of Australian bottle trees is in order. Members of the hibiscus family, bottle trees have rubbery, hydrophobic trunks that allow them to withstand lengthy periods of drought.
Four species, all represented at the arboretum, are encountered: common bottle tree (Brachychiton populneus), whose delicate, kinetic foliage has been compared to that of a quaking poplar; Queensland bottle tree (Brachychiton rupestris), whose obese trunk and scant foliage impart a stark, Dali-esque quality; flame tree (Brachychiton acerifolius), with brilliant red flowers; and lacebark (Brachychiton discolor), with pink flowers.
All bottle trees bear large black pods that contain rows of seeds with a startling resemblance to corn. Seeds germinate easily and make it eminently feasible to create a bottle tree forest, should you have the desire and the space to do so.
Cow itch tree (Lagunaria patersonii) is another hibiscus family member native to Australia. Cow itch tree exhibits columnar growth and is covered with a stunning lavender-pink floral curtain at this time of year. Its only downside is the irritating hairs on its seed capsules. These hairs stick to your clothes and enter your nasal passages if you get too close to the tree when the capsules are present.
Other notable Australian specimens on display at the arboretum include a young grove of weeping cabbage palms (Livistona decipiens); a honey myrtle (Melaleuca huegelii); and a delicate-leaved Totara tree (Podocarpus totara).
Tip of the week
I am well-acquainted with an extensive clump of balsam (Impatiens balsamina) that self-sows continuously and in great profusion. This is a highly recommended annual for full to partial sun and I suggest you spread a packet or two of balsam seeds for a constant display of its flowers. Since its roots are shallow, balsam may be used as a ground cover around roses without fear that the balsam will compete with the roses for water or fertilizer.
The more commonly seen shade-loving impatiens or busy Lizzie (Impateins walleriana) will also self-sow but soil must constantly be moist for this to happen.
Balsam, on the other hand, can endure periods of dryness and self-sow all the same.

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