Tasmanian Plants

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.

There are rather few genera of native Tasmanian plants that share the same genus as the common economic food plants we see in the market everyday. Some examples might come as a surprise however. For instance, Tasmania has one native plant which is a close relative of the CARROT!

The carrot of commerce is botanically known as Daucus carota spp. sativa. In the wild, the species is often referred to as Wild Carrot or Queen Annes Lace. The carrot belongs to the Celery family (Apiaceae), a large botanical family which also includes many plants which will immediately be familiar to the general public, eg fennel, parsley, parsnip, pennyworts, caraway and even hemlock, the source of the poison that killed the famous Greek philosopher Socrates. While the carrot is probably one of the most well known, the genus Daucus actually consists of some 60 species worldwide.

When I saw Tasmania’s answer to the fleshy and succulent carrot of commerce I was pretty amused. This was a small grassland herb, the Australian Carrot (Daucus glocidiatus), which would easily be overlooked as some inconspicuous weed.

Unlike the Wild Carrot, with numerous flowers in showy umbels, the Australian Carrot has a few inconspicuous whistish-pinkish flowers borne on an irregular umbel.

I try not to pick entire plants if I can help it (pretty wimpy for a botanist I know) but I couldn’t help it when it came to this little herb. I just had to check out it’s subterranean parts to see if there was anything carrot-like about this curious little herb.

Turns out that the Australian Carrot does have a taproot but nothing that a bunny would pause at to consider. The affinity of the Australian Carrot to the carrot of commerce had to lie somewhere else.

In the field this little herb is rather easy to identify. Few other native grassland herbs have such finely dissected pinnate leaves. In particular, the small bristly fruits make it instantly recognizable.

And indeed, it is probably the fruits that betray the affinity of the Australian Carrot to the carrot of commerce. In both species the fruits are bristly. In the Australian Carrot, the bristles on the fruits are barbed, as alluded to by the specific epithet ‘glochidiatus‘, which means barbed fruit.

In European herbal lore, the seeds of the Wild Carrot is known to have contraceptive properties (see webpage). If we were to make some extrapolations and speculate, could not the seeds of the Australian Carrot also be used for similar purposes? There certainly is the potential for such medicinal research on native plants.

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.

There must be hardly a single Tasmanian who has never seen the Sagg (Lomandra longifolia), one of the most widespread and common of plants in Tasmania. It is also widely cultivated as a native horticultural plant.

Despite being a very common element in the Australian flora, the Sagg and it’s relatives have a rather complex family history. While the Sagg resembles a sedge or a grass, it is nowhere related to these two plant groups.

Some people refer to Sagg and it’s relatives as a mat-rushes, but these again are nowhere related to the real rushes (Juncus spp.).

Plant taxonomists have placed Lomandra variously into the Grasstree family (Xanthorrhoeaceae) and even into a family of it’s own, Lomandraceae. Surprisingly, the Angiosperm Phylogeny Group suggests that the Sagg is a member of the Laxmanniaceae, the same family to which Chocolate lillies or Vanilla lilies (Arthropodium spp.) and fringelilies (Thysanotus spp.) belong.

Despite grasses and grass-like plants being very difficult for the budding naturalist to identify, the Sagg is extrmely easy to pick out.

In a non-flowering state, they can be easily picked out by their forked leaf tips. When in flower, the heads of cream flowered blossoms subtended by bract-like spines cannot be mistaken for anything else.

Not surprisingly, the Sagg was one of the first plants I learned to recognize in Tasmania. However, I never knew that Sagg could be a snack until I read Tim Low’s Wild Food Plants of Australia. (Read also my DISCLAIMER)

The white inner leaf bases of the plants are apparently edible and according to Tim, tastes like fresh green peas. I wanted to try for myself and so harvested a few stems.

Proper care should be taken when harvesting Sagg stems. I ran my fingers gingerly all the way down to the base of the plant and felt around till I could get a good secure grip before pulling the plant out of the ground. This I did because the leaves, like many sedge leaves, have edges which are more than capable of giving one a serious laceration. The leaves were apparently used by aboringes as material for basket making of which I have written of in a previous post.

The base of the stem is whitish and cylindrical and is fine to just chew  on. One could also remove the leaf bases around the stem base and get to the pith, which has somewhat the texture of a bamboo shoots.

I agree with Tim though that the Sagg makes a refreshing snack.

I also tried out the flowers but they were rather tasteless. Perhaps evening was not a good time to eat the flowers. In any case, if the flowers are to be eaten, do be careful of the ‘spines’ on the inflorescence. Not nice perforating one’s tongue or lips.

Nevertheless, bush rambling will never be the same again now that I have been initiated into the Sagg snack.

Mitrasacme pilosa var. pilosa (Hairy Mitrewort). Peter Murrell Nature Reserve.

Mitreworts refer to a group of plants of the genus Mitella from the Saxifrage family (see wiki article). These are temperate and arctic North America and Asian plants which, as far as I know, do not occur in Tasmania.

However, the practice of assigning the same common names to plants that are totally not related to one another has been going on for a long time.

It is therefore of little surprise that we find in Tasmania a number of plants called mitreworts as well. These are small herbs which hail from the Loganiaceae, the botanical family that houses the infamous Strychnine tree.

M. pilosa var. pilosa (Hairy Mitrewort). Closeup. Peter Murrell Nature Reserve.

This post is about a small herb known as the Hairy Mitrewort (Mitrasacme pilosa), a widespread species which often occurs in sandy heaths.

Whilst rambling around Peter Murrell Nature Reserve I stumbled on a small patch of what I believe is this plant near a ditch full of exotic grasses.

The plant was an attractive, neatly compact and prostrate herb. It had hairy stems with opposite leaves. In particular, the calyces were extremely hairy. The Hairy Mitrewort came to mind.

I had previously seen the Hairy Mitrewort before in a sandy heath on the Tasman Peninsula but after dredging up the photo I found that the two plants looked rather different.

M. pilosa var. stuartii (Stalked Hairy Mitrewort). Tasman Peninsula.

The one I found at Peter Murrell was compact, had very short pedicels (flower stalks) and extremely hairy calyces whereas the one I saw at the Tasman Peninsular was a less compact herb and slightly erect, had a very long flower stalk, and a close to hairless calyx.

Going back to the Student’s Flora of Tasmania, I found a description of the plant in Part 3 of the flora where Curtis writes:

‘The variants of with flowers borne on long pedicels have been distinguished as var. stuartii. Extreme forms, i.e. those with almost sessile flowers (flowers born on a very short stalk) and those with flowers on pedicels c. 3 cm long are very distinctive.’

This being said, it is probably safe for me to conclude that the Tasman Peninsula specimen belongs to var. stuartii and that the Peter Murrell specimen belongs to var. pilosa, which is the only other variety present in Tasmania.

M. pilosa var. stuartii (Stalked Hairy Mitrewort). Closeup. Tasman Peninsula.

Still, the disparity between the two varieties makes it difficult to accept at face value that it is all the same species. The long pedicels versus the short pedicels on the different varieties would make most think the two were different species. Moreover, the difference in hairiness could also strengthen the argument that there might be two different species here.

According to the Student’s Flora though, plants from different localities exhibit a range of variation, making the assignment of a specimen to a variety difficult in some instances.

As with the Finger-orchids I have written about, this is possibly a species complex worthy of a further taxonomic-molecular study.

Ask anyone about grass, sedges or rushes and they’ll probably nod in acknowledgment but mention bristleworts and you would most probably get a blank look.

Yet bristleworts and their relatives are a conspicuous component of the Tasmanian vegetation. Anyone who has visited Tasmanian’s wonderful alpine environment has likely seen one, even if they didn’t recognize it as a bristlewort or relative.

Bristleworts are from the Centrolepidaceae (Bristlewort family) and in Tasmania consist of only 3 genera including: Aphelia (Fanworts) – 2 species; Centrolepis (Bristleworts) – 8 species &; Gaimardia (Pincushions) – 3 species.

A fair number of species of Centrolepis and Gaimardia are endemic to Tasmania. I have not had the pleasure of seeing Aphelia but Aphelia is probably the easiest to tell apart from the other two genera because the inflorescence is a spike with numerous bracts.

Centrolepis monogyna (Cushion-bristlewort)

Many species of Centrolepis and Gaimardia on the other hand, look very alike. Both genera have members that occur in alpine/subalpine environments and exhibit a densely turfed lifeform (like above).

The Student’s Flora of Tasmania gives a very straightforward way of telling this two genera apart, if we are just willing to take a close look.

Centrolepis monogyna (Cushion-bristlewort)

Apparently, the bracts of Centrolepis are opposte or near opposite whereas those of Gaimardia are clearly alternate (i.e one is above the other).

Gaimardia fitzgeraldii (Wooly Pincushion)

I imagine it might be quite difficult tell these two genera apart when they are not flowering. Maybe the late Dennis Morris would be able to. He co-wrote the flora after all.