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 Rodway also published a series of monographs, the Tasmanian Bryophyta, between (1912-1916) which, although outdated, still stands as the most complete work on Tasmanian bryophytes by a single author.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.

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!

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.

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!

To the untrained eye it is possible to mistake certain flowering plants as mosses. Tasmania has a few examples, particularly some of the alpine bristleworts, which are small and turfed and even produce flowering stalks that superficially resemble moss capsules.

Much less likely is it for mosses to be mistaken as flowering plants, but yet, this was exactly what happened to a certain Australian moss by the name of Gigaspermum repens.

G. repens is a moss I had always wanted to see but Tasmania was not the best of places to be looking for it as it more typical of bare dry soils. This spring I was most fortunate to stumble on a small population near a rock outcrop on the summit of Mt Nelson.

The pale silvery quartz colour of the shoots were scarcely half a centimeter tall and reminded me of the ubiquitous Silver Moss (Bryum argenteum). Fortuitously, the plants I found were fertile, and in that state, there was absolutely no mistaking them. The fertile shoots were more than twice the size of the sterile ones and were, for lack of a better word, so pregnant.

Unlike most mosses which have capsules borne on a stalk held above the plant body, the capsules of G. repens were nestled among large modified leaves.

In this fertile state, plants are not dissimilar to minute flowers in bud. The capsule of Gigaspermum repens has a large operculum which falls off when the capsules are ripe, leaving a great gaping mouth and exposing the characteristically large spores (hence ‘Gigaspermum‘ which means large seeds) that are just visible to the naked eye.

These large spores could be mistaken for seeds in a pyxidate capsule, a type of fruit in flowering plants like plantain (Plantago spp.) where the top falls off to release the seeds. The uniqueness of Gigaspermum has inspired bryologists erect a botanical family, the Gigaspermaceae, to accommodate it.

When the great 19th century plant collector Ferdinand von Mueller (1825-1896) found this plant, he allegedly thought it was a flowering plant belonging to the ice plant family (Aizoaceae) and named it Trianthema humillima.

Mueller was a first rate botanical collector and his mis-description is no reflection of the lack of expertise on his part. Mueller was certainly aware of what mosses are. However, this episode does bear testimony to the morphological diversity that mosses can encompass, sans flowers.

I finally managed to take the time out to pop down to the Morris Miller Library, UTAS, to have a good look at the Moss Mania exhibition. Unfortunately I had missed the launch of the exhibition due to sickness.

The exhibition was situated in the exhibition cases at the entrance of the Morris Miller library, with Dr Rod Seppelt’s work was featured in a row on top, and those of Lauren Black were at the bottom. Immediately apparent was the contrast in artistic styles of the two masters.

Rod’s work was done in Indian ink on polyester film, producing a bolder effect. It also included technical histological illustrations of leaf and stem sections. Lauren’s work were pencil drawings and had a more aesthetic feel, with a focus more on capsule details. Nevertheless, it is without a doubt that both are first rate artists and have achieved mastery of their craft.

In addition to displaying the botanical artwork of Dr Rod Seppelt and Lauren Black, the Moss Mania exhibition also featured an impressive number of old books and short biographies of botanists and botanical artists involved in the early years of bryology (the study of bryophytes).

An example of one priceless volume was a book published in 1798, the Theoria generationis et frutifications plantarum cryptogamicarum Lannaei: retractata et aucta by Johann Hedwig. Book titles were rather verbose at that time, it would appear.

While it might seem alien in our current times where virtually everyone spots a camera, some of the early books on bryology actually had real specimens pressed between it’s pages. I had only ever read of something like that until I saw it with my own eyes in the exhibition.

The only other logical means for those early bryologist to depict the subjects of their study would have been via illustrations, and this art it seems, was elevated to a rather sublime level by the 19th century. They even had a system of colour codes so as to accurately depict the colours of the plants they were illustrating.

Modest as the exhibition was, it is impossible to leave without an appreciation of the intricacies required in the craft of botanical artistry, and the rich historical context that has culminated in the sublime artwork of the women and men who continue this admirable art-science synthesis.

The Moss mania exhibition continues till the end of November.

Artist profiles:

Lauren Black studied at the Royal Botanic Gardens, Melbourne and has been producing botanical masterpieces since 1997. Lauren has won numerous awards for her artwork and continues her work as a freelance solo artist and teacher A more detailed profile may be found on her professional website.

Rod Seppelt joined the Australian Antarctic Division in 1978 and is a adjunct professor at the Institute of Arctic Biology, University of Alaska, USA. He has published a book, The Moss Flora of Macquarie Island, and continues to work on drawings for projects like the Flora of Australia. His profile may be seen at the Australian Antarctic Division’s webpage.

When it comes to the sexual behavior of Tasmanian bryophytes, there are no lack of interesting species with juicy stories. One such moss is Rhacocarpus purpurascens.

This is a moss that typically grows on rocks in alpine regions and can frequently be seen submerged in alpine tarns. I never fail to look out for it everytime I visit such areas.

Oddly however, R. purpurascens it also occurs on large boulders at much lower altitudes near to sea level (see my previous post on my Cataract Gorge visit). Not a great deal of native plants can claim to have such a wide ecological range.

R. purpurascens is a very distinctive moss once known. The leaves have very fine hairpoint tips are arranged spirally around the stem in a very regular and neat fashion, conferring to the shoots a beautiful braided effect. Also, the brighter hues of the new shoot growth often contrasts beautifully with the older and darker parts of the plant.

I dedicate this post to R. purpurascens because this is the first time I am seeing it in fruit.

Since 2006 I have been looking out for capsules on this moss, particularly everytime I got to visit alpine areas. Interestingly, Paddy Dalton, a leading bryophyte specialist in Tasmania, has never seen R. purpurascens capsules up in the alpine areas in all his years of bryologizing. Oddly, he has observed it fruiting in Cataract Gorge, a lowland area. Paddy has written about this in the 35th Volume of the Bryological Newletter.

The elegant capsules are vase shaped and borne on a fine stalk (in bryological terms refered to as a seta).

I found fruiting R. purpurascens in the most unexpected of places – at Knocklofty Reserve. It was growing off a chunk frequently soaked exposed dolerite on the top of a cliff face.

Not only was it fruiting, there were dried capsules indicating that it must have been fruiting in at least the year prior as well.

My conclusions about this interesting disparity in fruiting behavior mirrors what Paddy wrote in his article, that phenological (study of flowering/fruiting behavior) investigations will be necessary to find out what is going on with the populations up the mountains.

Perhaps what we are seeing is a very versatile moss that chooses procreation when the conditions serves it but opts for celibacy instead under the harsher, colder environments on the tops of mountains. In the latter case, it has somehow managed to reproduce itself asexually and has been very successful at doing so.

Whether sexual or celibate, alpine or lowland dweling, R purpurascens has been hugely successful.

It was a busy and tiring week and I needed some fresh air. We (my partner and I) therefore made an almost impromtu decision to make a trip down to Marriots Falls this weekend Saturday. I had been on the track once during the Australasian Bryophyte Workshop in 2007 but I never got to the falls, distracted by all the bryophytes along the trail.

This time I was determined to get to the falls. I had an ulterior motive though…

Castanoclobos julaceus, as photographed from a collection during the 2007 Australasian Bryological Workshop

During the bryophyte workshop, someone had collected an interesting liverwort, Castanoclobos julaceus. This liverwort from the family Trichocoleaceae is interesting because it is a rare plant in New Zealand and was originally known only from New Zealand. There are however a number of older collections from Tasmania which were not verified until recently. Interestingly, this liverwort appears to be more in Tasmania than in New Zealand. Still, it is by no means very common here. I wanted to meet it and photograph it in situ. I had previously only seen and photographed it from a fresh collection under the kind permission of the collector during the bryophyte workshop.

The track was much wetter than I remembered, possibly because of the recent rains. I managed to hold off the urge to look at bryophytes but this time it was the numerous fungi that slowed us down.

There were just so many of them I simply could not photograph everything. Also I’ve really got to get a copy of Bruce Fuhrer’s toadstood guide. Seeing all those lovely toadstoods without a name to mind was driving me nuts.

I digress.

After numerous stops photographing toadstools (and some bryophytes) we finally reached the fall. It was spectacular. The water volume was so tremendous we had to take a photo from a distance to prevent the mist from getting onto our lenses.

Then after getting over my awe of the spectacular sight I hunted around for my quarry, the Castanoclobos. It was to no avail. I simply couldn’t find it, large and showy as the species is. Maybe it was hidden behind the curtain of water. That was a major disappointment.

We had to leave before the sky got dim. We were wet and our clothes were soiled by the end of it all but the walk was nonetheless a wonderful one.