Tasmanian Plants

Eucalyptus viminalis (White Knight)

It is common knowledge that the Mountain Ash (Eucalyptus regnans) is the worlds tallest flowering tree and that Tasmania has some of Australia’s tallest old growth forests. So magnificent are the Mountain Ashes that significant individuals  have earned appellations such as ‘Centurion’ and ‘Methuselah’. Alas, the legend of the Mountain Ashes have overshadowed the other giants that reside in Tasmania. There are other giants among the eucalypts that are worthy of more general recognition, and it may come as a surprise to some that the White Gum (Eucalyptus viminalis) is one of them.

Practically every plant enthusiast in Tasmania and many tourists who visit the state has seen the grand Mountain Ashes of the Styx or the Tarkine. Few however, even among Tasmanian botanists, have met or are even aware of the giant White Gums of Tasmania’s Northeast. This is because White Gums are often thought of as average sized trees  associated with dry forest. Yet, in the Evercreech Forest Reserve just 10km from Fingal, a forest of giantic white gums, locally called White Knights, preside over the wet forests. For centuries they have watched, like silent sentinels from their statuesque vantage point, the changing landscape of Tasmania’s Northeast. The time is nigh for the White Knights to take their rightful place in the annals of Tasmania’s rich botanical heritage, for nowhere else in the world does one encounter white colossuses such as these.

Another magnificent White Gum in stark contrast to the verdant wet forest understorey

In the 1970s a forester named Des Howe was carrying out a routine survey in the forest about to be fell when he noticed that one of the trees that was to be felled was very tall. A surveyor came in and measured the tree to be an incredible 91m. A more accurate measurement of 89m was later given in the gianttrees website. Girth-wise, the White Knight is just as impressive, being 3.3m in diameter. The White Knight is also believed to be over 300 years old. Due to the presence of the White Knight, 52 hectares in the area was made a forest reserve to preserve the White Knight and other giant White Gums that reside there.

The story goes that botanists initially did not believe that the tall tree reported by the Forestry Commission was a White Gum until leaf and fruit specimens were brought before them. Likewise for me, my experience of the white gum being a average size tree of dry forest was so ingrained that I would have scarcely believed that the White Knights were White Gums until I saw the characteristic seed capsules myself.

It is not difficult to see how the first foresters who came before the presence of the giant white gums likened the trees to Knights, perhaps spotting shiny-clad armour. White has always been the colour of purity and goodness, and there is nothing quite like the sight of Brobdingnagian white boles standing in blazing contrast to a deep green forest understorey. And I am properly awed and impressed, just as the visitors before me that have come to pay their obeisance to the White Knights.

The elephantine girth of the White Knight

Students of mosses (muscologists) have their agendas to see the Globe Moss when they come to Tasmania.  For students of liverworts (a.k.a hepaticologists), Tasmania houses yet another bryological treasure – a genus of liverworts known as Treubia.

Worldwide, Treubia has consists roughly 6 members of a largely southern hemispheric distribution. Proudly, Tasmania has two members of Treubia, T. tasmanica and T. lacunosa. These are among the most unmistakable of liverworts. Ironically, the appearance of Treubia has puzzled bryologists for decades since famed plant morphologist Karl von Goebel described the genus in 1891.

Liverworts in general, can be divided into two broad groups based on their appearance. These are thallose liverworts with flattish bodies without clear stems or leafy liverworts, which usually have clearly defined stems and leaves.

Treubia on the other hand doesn’t fit very well in either. It would not be too accurate to claim that Treubia has a stem. That would mean it is thalloid. However, from this ‘thallus’ arises many flaps of what look like leaves.

Tasmania’s very own early bryologist Leonard Rodway said of  Treubia tasmanica in 1911:

Many authorities try to avoid the breaking down of established systems by treating the lateral expansions as lobed portions of lateral wings. This seems a distorted description of the apparent structure, and does not tend to a clear understanding of the evolution of the hepatics.

Some bryological giants like Rudolf Schuster and George Scott interpret Treubia to be the midway point between the primitive thalloid way of life in liverworts to the more advanced leafy upgrade. To draw an analogy with animals, Treubia would be to liverworts what velvet worms (Onychophorans) are to invertebrates.

How does this ‘halfway house’ theory fit in with what is known of the molecular phylogeny of liverworts?

Molecular work has shown Treubia to be one of the most basal groups of liverworts, related to yet another morphologically enigmatic group of liverworts of the genus Haplomitrium (which incidentally is alleged to occur in Tasmania as well). Together, Treubia and Haplomitrium form a group that diverged early from the the course of the liverwort evolutionary stream.

Lending strong support to the antiquity of Treubia is the fossil record, with Treubia-like fossils being among the earliest liverwort fossils known. Treubia can really be considered to be a ‘living fossil’ like the Wollemi Pine.

In my interpretation, the leaf-like morphology of Treubia is hence an innovation of it’s own and not an attempt to bridge the thalloid to leafy condition. Could the Treubia lineage then represent an independent attempt to make leaves?

We may not live to see the descendants of the Treubia lineage, for bryophytes features in general do not evolve very fast. But still, Treubia remains a reminder of the innovation and possibilities that even the ancient can strive toward. It is indeed a liverwort that that epitomizes the legacy of Gondwana!

A single field trip up toward the Central Highlands offers plenty for a plant lover to see and do. One thing that must be done however, is to pay homage to the cider gums (Eucalyptus gunnii) of the highland areas.

This cider gum is a tree of immense significance to Tasmania’s natural history. It is aptly named the cider gum for it’s sap, which has been reported to be used by the aborigines to make a much relished fermented drink (see article). I  was way too late to experience the spring sap that allegedly drips from the tree inviting all to partake of it’s sweetness. What would I give to try that out! It would be one of the most direct means of communion with the cider gum. On this occasion however, my objective was merely to make an acquaintance with the Cider Gum in it’s natural abode.

I drove along the Highland Lakes road north of Miena hoping to catch sight of some cider gums. There are two known subspecies, both of which are endemic to Tasmania. The more common one, E. gunnii subsp. gunnii (simply referred to as the cider gum) is well distributed throughout the highland regions of the southeast, central, and western Tasmania. The other subspecies, E. gunnii subsp. divaricata is known as the Miena Cider Gum, and has a much more restricted distribution to a small area around Miena around the Central Highland lakes. It’s status as a subspecies of the commoner cider gum was only recently elucidated in a publication by Prof. Brad Potts, Dr Wendy Potts and Dr Gintaras Kantvilas in 2001. Previously, the Miena Cider Gum was known as Eucalyptus divaricata.

I practically screeched to a halt when I sighted just by the side of the road, two large and stately trees which I suspected might be the Miena Cider Gum.

I got out and scanned the surrounds. There were quite a number of dead trees in the vicinity but these two trees were different. They exuded a vibe of vitality. I studied them intently, looking out for characters that might give me an opportunity for identification.

A low hanging branch gave me access to photograph a cluster of their leaves and their capsules. The adult leaves also had a slightly pale whitish (glaucous) appearance and there was the persistence of very glaucous, rounded and oppositely arranged juvenile leaves.

Prof Pott’s paper had mentioned that the capsules of the Miena Cider Gum also tend to be more glaucous. The capsules are supposedly a slightly more sub-urned shaped compared to the more consistently bell shaped capsules of the commoner subspecies.

The combination of characters of the Miena Cider Gum seemed to match the specimen I was looking and I am happy to conclude that that was what my specimen was.

More important than the dry an technical act of nailing an subspecific identity to the tree however, was the feeling of communion. Few experiences compare to an acquaintance with trees of such haunting magnificence and presence. There is no words for it, only feelings that linger. Silence would probably make the best conveyance of this.

When ardent students of mosses or bryologists traverse the globe to come to Tasmania, they will have, among the top candidates of their ‘to-see’ list, an `endemic Tasmanian moss. This is none other than Pleurophascum grandiglobum.

Rest assured that this moss lives up to it’s grandiose name. As this moss is so distinctive and significant, I’ll take the liberty to call it the Globe Moss, a name that I will use henceforth.

The moss was first described by Sextus Otto Lindberg in 1875, an early bryologist, in the Journal of Botany. He wrote (annotations in parentheses mine):

‘I Have to-day received from my friend Baron F. von Mueller, the renowned Director of the Botanic Gardens of Melbourne, a small tuft of a Moss, gathered this year by Mr. Robert Johnston on turfy soil near Picton River, in Tasmania. This Moss is of the highest importance, indeed of no less interest to the Muscologist (moss specialist) than is Rafflesia or Welwitschia to the Phanerogamist (higher plant specialist). It is, in fact, a very robust Phascaceous (bud-like) plant with the fruit perfectly lateral on the stem! I dare not as yet call it truly pleurocarpous (fruiting from specialized side branches), as its affinity is most obscure; but as it has, as far as I know, not been described, it ought to be called Pleurophascum grandiglobum…’

The Globe moss appears to be largely restricted to Buttongrass sedgeland habitats in the western part of the state. In a sterile state, the leaves are beautifully and symmetrically arranged around the stem and from the top look like the way lotus petals are arranged around their flower axis. The leaves are almost cup-like, lack nerves, but usually, although not always, have a single hairpoint at the apex. These characters, with the additional habitatual context, renders the Globe moss difficult to mistake for anything else.

When this moss is in fruit however, it is most unmistakable! The green spherical capsules, which ripen a dull yellow-brown, are 3-6mm in diameter, and are possibly among the largest, if not definitely the grandest, of all mosses in Tasmania. These grand structures that gives the moss it’s specific epithet ‘grandiglobum‘ are borne proudly on long setas (or stalks).

The capsules are cleistocarpous, a sophisticated way of saying that it does not open regularly through a well defined mouth, but rather, splits open irregularly at maturity. Precious little is known about the dispersal mechanism of the spores, much less on why the moss appears to be restricted to Buttongrass sedgeland habitats.

There are other reasons as to why the Globe moss is of such botanical interest. The distribution of the members of Pleurophascum are highly disjunct. One species P. ocidentale occurs in Western Australia. Another species, P. ovalifolium, occurs in New Zealand and was only recently determined by Australasian bryologists Alan Fife and Paddy Dalton in 2005 to be a different species from P. grandiglobum.

The affinities of Pleurophascum to other mosses are unclear. Bryologists have variously proposed that it is related to the Bryum (the Bryaceae) or Pottia (the Pottiaceae) mosses, but until more convincing evidence surfaces, it is best that the Globe moss remain in a family of it’s own, the Pleurophascaceae.

If there should one day be an international exhibition of mosses, where every country were to submit a portraiture of a unique indigenous moss for exhibition, there can be little doubt that the Globe moss will be the prime candidate to represent Tasmania’s bryological heritage. As far as mosses go, the Globe moss puts Tasmania on the world map.

Hybridization as a means of making new species is not an uncommon concept and hence it must be applicable to other species. I present a case using a Tasmanian example – the Olearia daisybushes.

Olearia is a large and conspicuous genus of shrubs in the sunflower or daisy family (Asteraceae) with some 23 species in Tasmania of which 8 are endemic to Tasmania (not counting subspecies).

Left: Geebung Daisybush (Olearia persoonioides); Right: Prickly Daisybush (Olearia pinifolia); Centre: Possible hybrid

Two of the endemic species are of interest in this post: Olearia persoonioides (Geebung Daisybush) and Olearia pinifolia (Prickly Daisybush). Both are common and largish daisybushes that grow in subalpine woodlands.

Whilst botanizing at various spots around the Central Highlands I stumbled upon the two species of daisybushes growing in close proximity in the understorey of a eucalypt woodland. They were both in full flower. At the same time I also noticed numerous specimens that looked like intermediates between the two.

While this intermediate specimen deserves much more detailed study, I have prepared a set of photographs and made a table of the characters comparing the two daisybush species with the intermediate specimen.

Many additional aspects of the morphology of the intermediate specimen deserves study. For example, the morphology of the flowers and fruits (achenes) needs to be examined in greater detail. Other studies like chromosome counts might also be helpful in determining the hybrid status of the intermediate specimen.

A trip to the herbarium is in the works!

We don’t look one bit alike, but we are family.

That happens to be the story of a rather obscure group of bryophytes and exemplifies how drastically molecular technology is changing how bryophyte taxonomists study and classify this fascinating group of plants.

Whenever I visit dimly lit gullies in wet forest I always try to look out for bryophytes, one of which is a rather nondescript moss that used to be known as Echinodium hispidum. It was the only one of it’s genus in Tasmania and the nearby New Zealand has another species, E. umbrosum.

A very limpid way of describing this moss without getting into a tirade of alien sounding botanical terms would be to say that it is branched, has spirally arranged leaves that are widened toward the base. A look under the microscope will reveal the nature of the leaves.

Strangely, it is probably the combination of it being rather nondescript and it’s preference for dimly-lit gullies that enables almost instantly recognition of the species for the trained eye.

The genus Echinodium was erected in 1866 and was honored a family status of it’s own, the Echinodiaceae in 1909. Within bryological circles however, the family and genus is of some interest because of it’s anomalous distribution of it’s members: out of 6 species, two are found in Australasia (Australia and New Zealand) and four in Macronesia.

Earlier in 1986, taxonomist Steven Churchill was starting to sense that something was quite amiss with the species of Echinodium. He included all 6 species under Echinodium but was prudent enough to suggest the genus could potentially contain species that are not related to each other.

However, observant as Churchill was with the light microscope, the ‘molecular microscope’ was about to throw a spanner into the works.

In a recent study in 2008, Michael Stech and colleges, compared the specific DNA sequences of the six Echinodium species with species of other moss genera and found robust evidence that the six species of Echinodium did not form cohesive group. The Macronesian species largely remained in the Echinodiaceae but the two Australasian species were actually found to be more closely related with a totally different genus of mosses, Thamnobryum, a member of a totally different moss family, the Neckeraceae.

With such definitive prove of the new generic relationships, Stech and colleges renamed Echinodium hispidum to Thamnobryum hispidum.

Now, while mosses are simply mosses to some, anyone who would take even just a cursory look at the now T. hispidum and compare it to other species of Thamnobryum will find it hard to reconcile this new relationship.

For instance, the commoner Thamnobryum species in Tasmania, T. pumilum, is somewhat dendroid (shaped-like a tree); the leaves are flattened in a single plane; and the plants tends to produce thin wiry branches in addition to normal ones.

No familial resemblance whatsoever between the two species.

Molecular-based taxonomies of bryophytes have lagged behind that of vascular plants but whatever little that has been done is already revealing some rather surprising and revolutionary information that is eroding the very foundations of established taxonomies of the 20th century.

There is always more than meets the microscope when it comes to studying bryophytes!

Pimelea sp. nova Schouten Island. Photo on right shows the raised leaf scars.

The Royal Tasmanian Botanical Gardens is a constant source of botanical discovery for me. Every time I visit I discover something that I’ve never seen before. In my most recent visit I wandered over to the East Coast collection where I spotted a large robust shrub about 1.5m or so tall. To my surprise it was a species of Riceflower (Pimelea).

Pimelea nivea (Bushmans Bootlace)

Riceflowers belong to the Daphne family (Thymelaeaceae) from which we get our ornamental European Daphnes.

In Tasmania, Pimelea is represented by some 17 different species of shrubs that occur in habitats as diverse as coastal heath to alpine shrubbery.

The larger species of Pimelea in Tasmania are often called Bushman’s bootlace because of the tough bark that peels in stringy ribbons.

The riceflower that was growing at the East Coast collection was probably planted there a year ago. It is an as yet undescribed species that was collected from Schouten Island, an small island just off the tip of the Freycinet Peninsula on the East Coast of Tasmania. Given the locality of it’s discovery, I assume it must be a lowland shrub. It was labeled as “Pimelea sp. nova Schouten Island”, ‘nova’ alluding to it’s newly discovered status.

Pimelea sericea (Mountain Riceflower)

As first impressions go, the Pimelea sp. nova has the stature of the Bushmans Bootlace (Pimelea nivea). However, the leaves are have silky hairs on both the upper and lower sides unlike the Bushman’s Bootlace which is clearly hairless on the upperside and densely white hairy on the underside.

As far as leaf details go then, Pimelea sp. nova looks more like the Mountain Riceflower (Pimelea sericea).

However, the Mountain Riceflower is smaller in stature, has pinkish flowers, and as it’s name suggests, is a high altitude denizen.

Another rather distinctive feature of the Pimelea sp. nova are the raised leaf scars. From written descriptions, the Silver Riceflower (Pimelea milliganii) also has such raised scars. Other leaf attributes also match Pimelea sp. nova quite closely. However, the Silver Riceflower is also a high altitude species and only known from the western mountains of Tasmania.

The key characters then that distinguishes the Schouten island riceflower must be its robustness and its habitat. Still, I look forward to reading the formal description of this new and interesting species in the very near future.

The Coral Heath (Epacris gunnii) is a fairly common shrub that may be found in wet heath to highland plateaus. This ornamentally attractive plant has heart-shaped leaves with a pointed tip and in it’s full flowering glory produces in a spike-like fashion, numerous flowers in the leaf axils.

In the Royal Tasmanian Botanical Gardens there are many cultivated plants of the Coral Heath, and in particularly, a double form that produces small Camelia-like flowers.

Even though I had the prior awareness the aberration of genetic mechanism of these double form plants, I was still pretty surprised when I stumbled on this strange phenomena of seeing a branch produce a ‘flower’, consisting of a whorl of petals, and have a new shoot growing out of the whorl of petals.

Just to be sure I even sliced the stem and ‘flower’ longitudinally to make sure and indeed, the new shoot just grew continuously out of the whorl of petals.

It is almost as thought the plant decided to make a flower but got sidetracked at the last minute and continued with vegetative shoot growth.

Makes one think, what exactly are flowers?

Many botanists must have pondered on this question.

Thankfully we have some theories.

Thus we learn in botany that flowers consists of four whorls of floral parts in the following order: sepals, petals, stamens (male parts) and carpels (female parts). All flowers are technically modifications of this scheme. And these whorls, some might be surprised to know, are actually modified leaves.

What might come as an even bigger surprise is that the theory of flowers being modified leaves was actually conceived over two centuries ago in the brilliant mind of Johann Wolfgang Goethe, the famous German poet and philosopher.

Goethe, in 1790, had no way of knowing the action of genes in the onset of flowering but his powers of observation would put many a scientist to shame. His insights were discussed his very aptly titled essay, Metamorphosis of Plants.

The concept of flowers being modified leaves might seem very abstract, particularly given the fact that flowers seem to be so different from leaves.

But therein lies the genius of plants. They transmutate. They morph. They make flowers from ‘leaves’. And here it seems our aberrant Coral Heath, leaves from flowers.

In my virgin days of botanizing, my eyes were glued on flowers. Flowers in the sense of trees, shrubs, twinners, lilies, irises, orchids, etc. These are beautiful, often showy, and definitely attention grabbing.

I was certainly not unique in my biasness.

On the naturalist front for example, there are many whose passions seem to revolve around particular group of flowers.

Orchids appear to be one such group. Practically every spring there will be courses or fieldtrips held in obeisance of orchids.

Then also, there is the annually held Springflower Spectacular, a public springflower show in the Hobart Town hall, where a smörgåsbord of native banksias, boronias, daisies, heaths, peaflowers, waratahs etc are displayed.

Always this ridiculous obsession with flowers!

But misunderstand me not.

The motive of this writing is not to marginalize flowers, but to exalt them.

In all the time I have been looking at plants I  have yet to find a single flower that does not personify beauty. I am merely believing that an attention only to showiness and colour is myopic.

Admit we must, that most of us have cared little to appreciate a certain group of flowers ― the grasses and their inconspicuously-flowered kin. By these I am referring to sedges (Cyperaceae), rushes (Juncaceae), cord rushes (Restionaceae), bristleworts (Centrolepidaceae), waterribbons (Juncaginaceae) and any others that fit the  the bill.

So while roses, tulips, orchids and lilies are most often the subject of poetic adoration, I have come to absolutely adore the oft-quoted phrase from Walt Whitman’s Leaves of Grass:

‘I believe a leaf of grass is no less than the journey work of the stars.‘

The diversity of overall form in grasses and their kin is staggering.

They can grow as turfs or tussocks, as creepers or sprawlers. They can be messy or elegant. They can manifest as towering forms inspiring awe from the tallest of man (eg Cortaderia, Phragmites) or invoke adoration as minute annuals barely reaching a few centimeters (some Isolepis, Juncus etc).

But the true artistic genius of grasses and their kin lie in their flowers.

Grasses and their kin have flowers born in spikes, panicles or racemes, their spikelets displaying a bewildering configuration of shapes, sizes and orientations. When we finally get down to the actual flowers, we find that petals are simply not their style. They prefer the pragmatism of well hung stamens and plumed feathery stigmas that captures the love in the wind. Yet, unadorned as they are, their finesse is extreme, and their strategy hugely successful.

They are found from the edges of the sea to the tops of the mountains, in dryland, wetland, forest and scrub.

Where grasses occur in natural assemblages abundant enough to be the most dominant group of plants, they form grasslands. As an ecosystem, grasslands are richly diverse, supporting a wide range of invertebrates, birds and other plants. Many of Tasmania’s rare plants occur in grasslands. Such is the irony that we make annual pilgrimages to grasslands to look for orchids.

A ramble in a grassland evokes an inexplicable feeling in me. My mind conjures up a time when man has a primal connection with grassy, savanna-like environments. I can sense that the evolutionary journey of man and that of grasses and grass-like plants were always linked in some inextricable way. We eat of their substance. We weave of their resilience. As a whole, few plants groups has had as great an impact on man as grasses and their kin. I’d go as far as to say that the  form of grasses and their kin is etched into our psyche.

My journey has brought me to a point where I am thoroughly smittened with grasses and the like, just as I have become smittened with various other plant groups. I imagine this is the natural and inexorable progression of anyone who is assiduously and incessantly in search of more to appreciate. I know that until I fully expend my capacity to see and know all that I can see and know, my appreciation of this vast plant world can never be complete. And therein lies the joy of botany.

Glasswort (Sarcorcornia quinqueflora) with flowers. Lauderdale, Southeast Tasmania.

In 2004 I encountered some strange growths on the glasswort (Sarcocornia quinqueflora), a common saltmarsh plant of the Amaranth family (Amaranthaceae) in Southern Australia and Tasmania.

Knowing little of the glasswort, I thought the structures were it’s succulent fruits. It was a few years later after I had encountered the phenomenon a couple more times that it started to occur to me that those structures might be galls. Winifred Curtis in the Student’s Flora described the phenomena as follows:

‘…short lateral branches or small groups of segments…enlarged and bright red in colour, superficially resembling flowers.‘

This was hard to believe as my impression of galls were deformed lumps on leaves or twigs that disfigured the overall appearance of a plant. The galls on the glasswort on the other hand had a symmetrically beautiful form, with tightly overlapping succulent scales forming a pegoda-like structure.

A quick search online brought me to the profile page of Dr Anneke Veenstra from the Deakin University. In 2007, she and co-workers published a paper on the minute gall midges that were the cause of the flower-like galls on the glassworts. They described the gall midge as Asphondylia floriformis, classed under the Cecidomyiidae, a family under the large order of Flies (Diptera). The specific epithet ‘floriformis’ alludes to the flower-shaped appearance of the galls.

Asphondylia floriformis galls on glasswort shoots. Australian $2 coin (c. 2cm diameter) for scale.

How the galls are formed has yet to be studied in detail but presumably this happens in spring when the adult gall midge deposits an egg via it’s ovipositor into the plant tissue. A local swelling then arises. The larvae of the gall midge then develops in a chamber of the gall. The chamber walls are also observed to develop a covering of fungal mycelia (threads), which I suspect might play some role in the development of the gall midge larvae. When mature, the gall midge makes it’s way out of the top of the gall and leaves behind the cocoon covering.

Gall sectioned to show inner chamber. The remains of the Asphondylia gall midge pupal skin is evident on the top of the gall.

Interestingly, glasswort plant collections with galls date back to the mid 19th century. The first known collection of the glasswort with galls on them was made in 1859 by German-born doctor and botanist Hermann Beckler in Hastings River, New South Wales. Since then, there have been numerous glasswort collections with galls from various Australian states, including Tasmania.

From the notes accompanying the collections, it is evident that some of the early collectors did not recognize the galls and thought they were floral parts. Another thought the galls to be vegetative plantlets that would eventually fall off to establish new plants. I imagine that some of these early collectors did not think that the swellings were galls because it’s ‘natural’ and aesthetic look.

In it’s normal, healthy state, the glasswort is by no means a highly adorned plant. The inconspicuous flowers are borne on fleshy spikes that look just a little more compact than the normal segments that make up the glasswort’s succulent body. Functionality and simplicity is it’s style. But when dealing with an attack from a natural parasite, the glasswort reveals it’s somewhat macabre capacity for morphological aesthetics. Few other plants can claim to have the gall to be beautiful.