Tasmanian Plants

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Portrait of Leonard Rodway (1853-1936)

A foray into the history of Tasmanian botany brought me to a website featuring what is perhaps the very first botanical-naturalist publication of Tasmania, a century old book titled Some Wildflowers of Tasmania (1910) by Leonard Rodway.

I had learned in my undergraduate years that Leonard Rodway was the head of the first herbarium, but this piece of information was anecdotal at best. There was much more to the man than just the ‘head of the herbarium’.

Leonard Rodway was born in 1853 in England to a dentist Henry Baron Rodway and his wife Elizabeth. He first trained to be a midshipman but eventually followed his father into dentistry. He migrated to Queensland and later Tasmania and was subsequently registered under the first Tasmanian dental act in 1884.

Dentist by trade, Rodway pursued plants during his weekends and holidays and in 1896 became the honorary government botanist.

A self-made authority on Tasmanian plants, Rodway published prolifically in the Royal Society of Tasmania. His magnum opus The Tasmania flora was published in 1903, and became the standard reference on the topic for 40 years until the era of Winifred Curtis began (which shall be covered in another post). Rodway also published a series of monographs, the Tasmanian Bryophyta, between (1912-1916) which, although outdated, still stands as the most complete work on Tasmanian bryophytes by a single author.

Ozothamnus rodwayi (Alpine Everlastingbush), an alpine daisy that bears Rodway's name

Rodway retired from public life in 1932 and passed away in 1936, aged 83.

In a time when the study, teaching and application of botany depended on the initiative of individuals and voluntary organizations, Leonard Rodway single-handedly raised and sustained the ford of Tasmanian botany. In that respect, it would not be too inaccurate to title him “the founder of Tasmanian botany”.

Rodway’s botanical achievements have been described as ‘a true gift to the people of Tasmania’. Several plant and fungal species bear the specific epithet rodwayi in his honour (examples are Eucalyptus rodwayi, Gahnia rodwayi, Entoloma rodwayi) and a number physical features in the Tasmanian highlands (eg. Rodway’s Pass in Mt Field National Park) perpetuate his memory. For the student of botany though, Rodway’s name will always be remembered through verbal transmission, when instructors of field botany pronounce the names of plants which immortalize Rodway.

It is most remiss of me, that I should write of one of Tasmania’s most iconic trees only now, after more than a year of blogging about Tasmania’s fantastic flora.

Introducing a tree that needs little introduction – Tasmania’s one and only deciduous native tree, the inimitable Nothofagus gunnii, the Deciduous beech, the Tanglefoot. There are those too, who simply call it the Fagus.

The Deciduous beech is a small tree from the beech family (Fagaceae). It reaches little more than 2 meters at the slightly lower altitudes but practically sprawls over boulders in the alpine zones. It is a mere dwarf compared to it’s much more widespread relative, the Myrtle beech (Nothofagus cunninghamii).

The legacy of the Deciduous beech however predates that of the Myrtle beech. As far as geological time is concerned, the latter is a much younger player in the biogeographical game.

Fossils very similar to that of the modern day Deciduous beech have been found in Antarctica, which leads one to conclude
very similar species were in Antarctica before Australia separated from that now snowed out landmass.

The deciduous nature of N. gunnii also leads one to think that deciduous-ness might have been a much more common feature of the Tasmanian tree flora in times past.

Alas, this is not really the easiest plant to visit. The Royal Tasmanian Botanic Gardens (RTBG) has at least one specimen, but it is a small one hardly more than 50cm tall, and it is largely obscured by other plants.

Obscured! That’s criminal, particularly given that an illustration of the deciduous beech graces the signboard at the entrance of the RTBG. Still, that is one of the closest places to civilization that one may visit this icon.

Most understandably, the Deciduous beech must be one of Tasmania’s most difficult-to-cultivate icon. It takes a long time to grow, if it even survives. Still, once it harmonizes with a sincere plants-person, a most exquisite bonsai plant the Deciduous beech will make.

But the connoisseur will seek the Deciduous beech in it’s highest abode. The true seeker must travel to the mountains to the west, during April of the Austral fall. They must drive west bound, up windy beaten roads, through the grand forest of the Mountain Ash. And where the road ends by the Dobson Lake, they must by foot alone traverse boulder and tarn, beyond where the highland gums surrenders to frost and exposure. Then, and only then, does the sincere seeker arrive at the Tarn shelf, a true mecca of nival endemicity, where the deciduous beech basks upon the alpine boulders in it’s most exposed, most brazen magnificence.

And then one may say that one has witnessed the leaf fall of the last of Tasmania’s deciduous, the yellow of the autumn Fagus.

I have been silent, like the plants I study.

There is no easy way to state this so I state it simply.

Swiftly but surely, my time in Tasmania has come to an end.

Five years I have been in Tasmania, the plant life there has left an indelible mark on my psyche.

Such are the ways of plants. They enter ones awareness in the most unobtrusive of ways. And they leave a void in their absence.

But this void is meant to be.

There can be no one who is touched by the grace of botanical beauty who will fail to strive towards attaining another glimpse of that drunken ecstasy.

The ecstasy of seeing yet another plant that I have never laid eyes upon, smell yet another Christmas mint, see the heath blossoms emerge for yet another year, and yet another year.

Five years in Tasmania. A lifetime of memories. Memories of flowers. Memories of ferns. Memories of trees.

And most of all, memories of the people whom have imparted to me their very own affection for plants, even though they might not have said so in as revealing a fashion.

I will continue to write of the plants of beautiful Tasmania, if only to commemorate the loveliness of her flora, but every post must necessarily now be one written from a great distance – a distance that make the heart grow fonder.

Leaves of the Fragrant Candlebush become 'incontinent' with age

There are more similarities between plants and humans than we give credit for. Introducing the concept of incontinence in plants!

Leaves are the key parts of a plant which carry out the important act of water exchange with the environment. This being so, how effectively a plant can use water depends on how the easily water vapour gets from inside the leaf through the cuticle (the covering cell layer on the surface of a leaf) to the outside.

Greg Jordan and Tim Brodribb of the School of Plant Science, University of Tasmania have been studying the physiology of plant leaves for some time now and in 2007 published a paper in the scientific journal Functional Plant Biology on an interesting finding that the leaves of Agastachys odorata (Frangrant Candlebush or White Waratah) actually become incontinent with age.

Agastachys odorata is an endemic plant of the Protea family (Proteaceae) and occurs commonly in the high rainfall western Tasmania. The leaves of A. odorata exhibit distinctive annual growth increments, making different aged leaves easy to tell apart. The leaves are also very long-lived, with evidence of some leaves remaining on plants for up to 21 years. This makes A. odorata a fabulous choice for studying plant water relations with regards to leaf age.

Greg and Tim wanted to test the hypothesis that water vapour leaks across plant cuticles more readily as plant leaves age. In A. odorata they found that the older leaves were less effective in controlling water loss and hence used water less effectively than younger leaves. The increasing permeability of the leaf cuticle is implicated as the cause for this but it is also likely that the ability to control stomata opening also decreases with age, much akin to poor urinary sphincter muscle control in sufferers of incontinence. Greg and Tim concluded that the decreasing ability to use water efficiently could be due to natural leaf damage that occurs throughout the life of the leaf.

When the leaves of A. odorata becomes too old, it is simply shed. After all, the plant has no lack of leaves to serve it’s physiological functions. If only humans had the luxury of replaceable urinary sphincter muscles.

A rather recent trend in molecular science has been to use the technique to extort genes to reveal the history of how a plant has extended it’s geographical distribution throughout time.

I have written about how researcher James Worth used molecular techniques to pinpoint the locations (refugia) where Myrtle Beeches (Nothofagus cunninghamii) survived during the last glacial period. Just earlier this year, researchers Paul Nevill, Gerd Bossinger and Peter Ades published a paper in the Journal of Biogeography doing the same for the Mountain Ash (Eucalyptus regnans).

As in James Worth’s Myrtle Beech study, the researchers looked for variations at specific locations in the chloroplast DNA in Mountain Ash individuals distributed throughout the species natural geographical range. Different individuals may exhibit specific sequences which may differ from region to region and these are known as haplotypes.

A large amount of haplotypes found in a population an any given area would suggest that the area is a glacial refugium as we would expect a species to have persisted for longer periods of time in a refugium, thereby accumulating genetic changes. Conversely, places with low diversity of haplotypes could be construed to have been colonized after the glacial period ended, as there wouldn’t have been time enough for a high diversity of haplotypes to develop.

The results of the study showed that Mountain Ashes of the Northeast and Southeast of Tasmania has a high diversity of haplotypes, many of which were unique to the region. This suggests that the Northeast and Southeast of Tasmania harbored refugia that sheltered Mountain Ashes during the glacial period. By contrast, the central parts of Tasmania had a lower diversity of haplotypes. Another way of interpreting this was that there was fixing of haplotypes in that region, suggestive of a more recent colonization of the area following the end of the glacial period.

One consideration that remains to be addressed is the ease with which Eucalypts hybridize. E. regnans for example may hybridize with E. oliqua (Stringybark) and E. delegatensis (Gum-topped Stringybark). Hybridization may result in chloroplast sharing between species and a more comprehensive study will probably be needed to ensure that all these factors are taken into consideration.

For now it seems we are getting closer toward reading the the silent tale of survival that the ancestors of the Mountain Ashes in the Northeast and Southeast have etched in the genes of their descendants.

I have deep respect for ferns living in harsh conditions and one such fern is  Asplenium obtusatum (Shore Spleenwort). This species is also present in New Zealand but the Tasmanian form is known as A. obtusatum subspecies northlandicum, a form that was described by the renown pteridoloist Pat Brownsey in 1977.

The Shore Spleenwort is allegedly common and grows on rocks along the coastline of Tasmania. Widespread as it is, I’ve only had the fortune of observing it growing on the cliff faces around the Remarkable Cave in the Tasman Peninsula and in the fernery of the Royal Tasmanian Botanical Gardens.

The fleshy and shiny fronds of this fern makes it instantly recognizable and reminds me of the Sea Spleenwort (Asplenium marinum) of the Northern Hemisphere, a fern I would very much like to meet. Being ferns of such similar habitats, I imagine some convergent evolution in form is at work here.

Asplenium obtusatum is tolerant of some salt spray, a remarkable feat indeed given the vulnerability of ferns during the earlier stage of their life cycle.

This earlier stage are known as the gametophyte phase, as opposed to the sporophyte phase that we call ‘ferns’. The gametophyte is an inconspicuous little liverwort-like a structure that germinates and develops from fern spores. In most botany textbooks the fern gametophyte is portrayed as a heart-shaped structure and is called the prothallus. It is from the prothallus that the male and female reproductive parts develop. When the time is ripe for fertilization, the sperm swims through a film of water to find an ‘egg’ to fertilize. From this union, a baby fern is born, growing out of the tissues of the prothallus. The cycle is complete.

Unlike flowering plants, the fertilization of ferns require a film of water as mentioned above. Imagine the physiological stresses that a fern prothallus has to endure when the occasional salt spray comes into the picture!

The Shore Spleenwort is indeed a hardy fern worthy of a lofty station by the magnificent cliffs of the Tasmania coast!

In Tasmania’s heaths, herbfields, cliffs, lake margins and among cushion plant communities of the Northwestern and Central highlands lurk one of Tasmania’s most elusive botanical secrets – a little lily that hails from a botanical lineage of great antiquity.

First though, we must clarify what exactly is a lily.

The natural history and taxonomic relationships within the large family of lilies (Liliaceae) often vexed botanists in the pre-molecular age. After botanists became well accustomed to assigning the appellation of ‘lily’ to a great many species of plants, the molecular blade swiftly and decisively ended the empire of the the lily family. Asparagus (Asparagus spp.), the onions (Allium spp.), the pineapple lilies (Astelia) etc.,  became allied to other plant Orders (as will be elaborated in another post!).

Some of the remaining members of what was once the Liliaceae still remain in what is considered an Order of Lilies, the Liliales. However, the members of this once colossal lily family grouped into smaller families of their own.

One family of lilies, the Campynemataceae, is of paramount interest. Molecular work based of the gene sequences of the RuBisCo enzyme (rbcL) that is present in the chloroplasts of all plants, tells us that the Campynemataceae lineage is the oldest among all that can still be considered a part of the great lily order. In 2004, researchers Thomas Janssen and Kårl Bremer compared the rbcL sequences of representatives of the families in the Lily Order and estimated the Campynemataceae lineage to have come into existence some 117 million years ago, as a sister group to all other families of the Lily Order.

The lily I have deemed to be one of Tasmania’s most elusive botanical secret is Campynema lineare (Green Mountainlily), a representative of the Campynemataceae.

C. lineare is endemic to Tasmania and is the only species in its genus, and Campynema is one of the two genera in the family. The only other members of this family is a genus of three species, the Campynemanthe, that hails from New Caledonia.

C. lineare is a slender herb up to almost half a meter in height, but usually much smaller in highland areas. The leaves are linear as the specific epithet ‘lineare‘ suggests’ but highly inconspicuous when the plant is not in flower. The blossoms are scarcely 2 cm across, with yellowish-greenish floral parts, borne on a brownish stem. This combination does not help in making it stand out well from the surround vegetation. Before releasing pollen however, the bright orange stamens do stand out quite clearly against the greenish floral parts, but in most other respects, C. lineare is a rather inconspicuous plant and not largely different from what anyone would call a ‘lily’.

A casual observer would not have guessed that it is a relict of ancient lilies. Probably not even Jacques Labillardière, the french botanist who described the genus in 1805, guessed that he was beholding a botanical gem.

But the time of awareness is nigh. In this digital and molecular age, inconspicuousness can no longer be an excuse for the lack of recognition suffered by this marvelous plant. It is time for the little Green Mountainlily to take it’s rightful place among the ranks of Tasmania’s iconic plants. Like the Delicate Laurel (Tetracarpaea tasmannica), we must sometimes know of the historical significance of such plants before we can truly appreciate their contribution to botanical heritage of this land we call Tasmania, a home to plant lineages of great antiquity.

Actually, it would be quite inaccurate for me to call this a pilgrimage.

My partner and I were on our way to Cradle Mountain and driving by Chudleigh when I noticed a strange building. Without a doubt, it was designed to catch one’s attention. It was the Melita Honey Farm.

The word ‘honey’ was enough to make me walk through those doors and when I did so I thought I found paradise.

Pure stacks of honey jars on the shelves, assembled as neatly as bees would construct their cells. (Pardon the bad analogy).

Honey… of a huge variety of flavors, of single origin honey of both Tasmanian and mainland trees and shrubs. Honey… also of some of exotic plants. Honey…blended with macadamia, ginseng, ginger…chocolate!!!…

Fortunately I did not have to buy a small tub of everything just to try. A wide selection of their honey produce was also laid out on a table in open jars for sampling. It was absolutely hedonistic.

Other than books and petrol, few things inspire a budget conscious botanist to whip out his wallet. I was not leaving the honey farm empty-handed. I got myself two small jars of honey, a bottle of non-alcoholic honey mead and a bottle of apple cider vinegar with honey.

Honey was not the only produce. There were beeswax products, propolis, nougats, royal jelly and more.

The shop itself was also partly a museum for a self guide tour, in which they featured documentaries of how their honey was made and even displayed a section of hive with live bees.

Perhaps what tickled my nerves the most was to see an ice cream bar in the shop selling honey ice cream! My partner and I got a leatherwood and Blue Gum ice cream respectively. The ice cream tasted like any good ice cream would but I suspect that it was dousing the curiosity it inspired that contributed the largest part to the satisfaction.

The honey pilgrimage to Chudleigh. Make it at least once in a lifetime!

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!