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Golden Glory: a story about the flowering of Australian wattles

Silver wattle in a garden setting (photo from Wikipedia)

There was a halcyon time in my long-ago forestry career when I spent a few years in the research division. My office was in the Forest Research Institute in Como, just across the way from the Departmental library. In those days the WA Forests Department's library was replete with historical and current literature about the world’s forests and their management. My most wonderful discovery was a whole shelf of dusty volumes: the collected editions of The Indian Forester, going all the way back to the 1870s. This turned out to be a treasure trove of articles, scientific papers, stories and commentary, covering the gamut from silviculture to shikar. I never tired of dipping into the early editions at random: there was always something of interest to read.

For example, in the 1882 edition of The Indian Forester. I came across a note from Major General Henry Morgan, the Deputy Conservator of Forests at Madras. He submitted a short article on the flowering of the Australian silver wattle (Acacia dealbata) tree in the Nilgiris Hills of India, and as I love Australian wattles, I read it avidly. Morgan observed:

The [silver wattle] trees were introduced on the Nilgiris before 1845 [and] a curious fact regarding the flowering has been observed. In 1845 and up until 1850, the trees flowered in October, which corresponds with the Australian flowering time; but about 1860 they were observed flowering in September; in 1878 in July and this year (1882) they have begun to flower in June, this being the spring month here, corresponding with October [spring] in Australia.....

.....It has taken these trees nearly 40 years to regain the habit of flowering in the spring. Commencing in October (our autumn), the trees gradually worked their way back to summer and finally to spring, where probably they will remain.

Discussing this intriguing story with a botanist friend one day, we agreed that it would be interesting to know how the progeny of these trees knew when to flower. The Major General does not make it clear whether he is talking about the same trees, or generations of trees. I suspect it is the former, although 40 years is a pretty good age for a silver wattle. In any case, it would seem to me most likely that seedlings from the June-flowering silver wattles in the Nilgiris would also flower in June, a response to the environment, rather than an inherited characteristic.

Nevertheless, a little niggle survives in my mind: presumably the original trees were grown from seed brought from Australia. Why when they first germinated and matured in India did they start to flower in the Indian autumn rather than the Indian spring?

Puzzled by this, I looked up the subject of the movement of wattles from the southern to the northern hemisphere and found that there is an extensive literature on the subject. This arises from the fact that seeds of many species of Acacia were collected by pioneering botanists who visited Australia in the early 19th century; the resulting wattles were then grown in botanic gardens in England. According to botanist Tony Cavanagh (a story passed on to me by Bruce Maslin, the doyen of Australian acacias), Australian wattles became:

...popular greenhouse plants, where they were grown in pots, or as conservatory specimens.....their popularity was due to their hardiness and rapid growth [and] their profuse flowering during the drab period December-May...

Mostly it was found that wattles that flower in the southern Australian spring (September-October) flowered in late winter-early spring (March –May) when grown in England. Reading the Cavanagh paper, a species that caught my eye, as once it used to tear my trousers, was Acacia pulchella, known colloquially as ‘buggery bush’ by Western Australian foresters because of its vicious prickles. In its native habitat in south-west jarrah forests it flowers in September/October (our spring), but plants raised in England from seed collected by Robert Brown in 1801 flowered in May (the English spring), apparently without a transitional period as occurred with Major General Morgan’s silver wattles in India.

Morgan concludes his article with this lovely note on Australian wattles growing in India: “On arriving in Ootamamund in the flowering time, the stranger cannot fail to be struck with the golden appearance of the trees, clothed with blossoms of the purest yellow.”

I know what he means. I love wattles and have grown a great many of them over the years, especially Acacia acuminata (jam wattle) and A. microbotrya (menna wattle) . The latter is remarkable in that it flowers in autumn-early winter (May-June) rather than spring.

Few things give me more intense pleasure than to stand and admire the glorious blossom on a wattle that I have planted and nurtured with my own hands.

A young menna wattle on our property at Gwambygine, just coming out into blossom in early May 2022. I grew this tree from a seed collected in the bush

The mature flowers of both jam and menna wattles (like most Western Australian wattles) are gold rather than yellow, although in the case of menna wattle, the flowers grade into a deeper golden hue in the northern wheatbelt.

Yellow blossom is mostly associated with the wattles of eastern Australia, of which the silver wattle, of course, is one. The most famous wattle is Acacia pycnantha, the floral emblem of Australia, which has the common name of ‘Golden Wattle’ (even though the flowers are yellow, rather than gold … but who cares?)

I have never grown silver wattle and will not do so, as it is an environmental weed in Western Australia, regenerating prolifically from seed and sucker growth, and expanding into local bushland where it forms dense thickets. But I have admired it overseas, especially in California, where it is widely planted as an ornamental (and where it flowers in January-February which is late winter or early spring, depending where you are in California). There it is immensely popular, for the very reason the Major General notes: it is a very beautiful tree and the intensity of its floral display must be the equal of any tree in the world.

The gorgeous blossom of the silver wattle (Acacia dealbata) belies the fact that it can become a serious environmental weed in Western Australia

But silver wattle is only one of over a thousand species of Acacia native to Australia, most of which are also exceedingly beautiful, and a large proportion of which are unknown to most Australians or are taken for granted.

One of the reasons for this is that the genus has so many species and is so widespread, occurring from the northern tropics to southern Tasmania and encompassing the arid interior. Moreover, there is an immense range of variation in habit and form, even within species. And across the range of species, there is also a wide range of flowering times. Silver wattle, for example, grows naturally on the east coast, from northern NSW down into Tasmania. In the more northern locations, flowering tends to commence in August, while in the south it can be as late as October.

Australia's National Wattle Day, incidentally, is celebrated on September 1st (other than in Queensland where it is held on August 1st, presumably because many Queensland wattles reach peak flowering earlier than those in the south). September 1st is a sort of mid-point for spring-flowering wattles in eastern Australia. Perhaps the seed used to establish the trees observed by the Major General at Nilgiri came from Victoria or Tasmania. But you can never be sure about something like this; even within the one region, flowering times can vary, depending on locality and seasonal effects.

Even within one species, growing in the same place, flowering time can vary. I have observed two menna wattles (A microbotrya), which I planted on the same day adjacent to each other; they come into flower 2-3 weeks apart. I have even seen the blossom on one limb coming out a week or two earlier than that on another limb on the same tree, a western myall (A. papryocarpa). And there are species of wattle growing in the arid regions of central Australia, including A. aneura (mulga) that flower only in response to rain and this might only occur once in many years.

All of this has takes me off on another tack. I have been looking recently at a remarkable document prepared by acacia-guru Bruce Maslin on the wattles of the Shire of Dalwallinu in Western Australia.

Typical fringing vegetation on a road near Dalwallinu, flowering wattles (A. anthocaera) providing a lovely display [Photograph by Bruce Maslin]

Located in the northern wheatbelt, the landscape around Dalwallinu is remarkable mostly for the endless, featureless wheat paddocks stretching to the horizon in all directions. But the Shire also encompasses some of the southern pastoral country, a number of small but important nature reserves and the usual network of road reserves still with their native bushland more or less intact.

Bruce Maslin has found that within a 100 km radius of Dalwallinu townsite can be found no less than 185 different species of Acacia – about the same number of Acacia species found in total in the continent of Africa and the Americas.

Included in the Dalwallinu tally is the widely distributed and quite stupendous Acacia victoriae, shown here in a glorious photograph by Bruce, sprawling over a garden fence:

Bruce Maslin has prepared a flowering calendar for these species, and this reveals a range of flowering times from April (A. daphnifolia) through to October (A. ligustrina) with every month in between represented as the peak flowering time for a particular species. All of these wattles are growing in the same climatic zone, although there is a fairly wide variation in habitat niche. A. hopperiana for example, is found only around granite outcrops and on deep sandy soils, while jam wattle (A. acuminata) is widespread on loams and clay soils, especially in association with York gum (Eucalyptus loxophleba) – which, like many eucalypts, flowers in mid-summer. A Dalwallinu-region wattle I have never seen but would like to grow is A.stanleyi, named after Kalannie farmer and forester Don Stanley. I was a fellow-member on the Board of Greening Western Australia with Don, and I came to admire him greatly.

A guru is honoured. John Maslin, Bruce Maslin and Roger Underwood at Government House, on the occasion of Bruce being awarded an Order of Australia Medal for his life-time research into (and passion for) Australian wattles

Finally, to return to Major General Morgan and his silver wattle trees in the Nilgiris Hills. How fascinating it would be today, to try to duplicate his observations by sending seeds of flowering wattles, with a range of flowering times, from Dalwallinu to the temperate regions of India, and to observe their flowering patterns over the next 40 years.

The trouble is, I will need to find a much younger forester than me to assess the trial when the 40 years is up!

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