Tasmanian Plants

As I have written in my post ‘the unbearable adorableness of turfed existence‘, small plants are very easy to love. Members of the Bristlewort family (Centrolepidaceae) in particular, meet all the qualifications. Most are turfed and all are small, barely attaining a stature exceeding a few centimeters.

Aphelia gracilis (Slender Fanwort)

For a number of years now I have been wanting to meet two specific members of the Bristlewort family, Aphelia gracilis (Slender Fanwort) and Aphelia pumilio (Dwarf Fanwort), particularly after I had seen illustrations and photographs of the two in The Student’s Flora of Tasmania Part 4B and The Nature of the Midlands.

Isolepis levynsiana (Tiny Flatsedge)

Other than the aesthetic allure of these plants. there are reasons for this eagerness,

For one, the genus Aphelia is endemic to Australian, that is to say, unique to Australian soils. Secondly, both the dwarf and slender fanworts are rare plants found only in parts of the Midlands and in the Northeast.

Adorableness and rarity. Such reasons are cannot fail to set off passions like rotating lights accompanied with sirens for plant lovers.

Needless to say, it did for me. So great my desire was to see these two fanworts and so swift was my alignment to this desire that in one fell swoop, I saw the both of them in a single day when I visited the Tom Gibson Nature Reserve on a Threatened Plants Tasmania group excursion.

The strange thing about these two plants is that there is little in the gist of it that would suggest that they are NOT sedges. Yet, they are so unique as to be recognizable at once. I shall explain.

A. gracilis spike

From every angle, these two plants look like small sedges of the genus Isolepis. The single spike (the flower cluster, consisting of many overlapping bracts) is laterally flattened and in practically every sense resembles the floral parts of Isolepis or Cyperus. When we come to this point we have got to stand in awe of the detail that plant taxonomists put into describing plants.

The Bristlewort family is probably best distinguished from sedges by their fruits. Bristleworts have dehiscent fruits, meaning that the fruits split open to expose seeds at maturity. The fruits of sedges, on the other hand, are indehiscent nuts. This fruit characteristic of Aphelia is difficult if not impossible to see in the field. Moreover, these plants are so small that you’d need a microscope in the field at the time of fruit maturity to look at it – not very logistically appealing for an afternoon walk.

On my plant hunt with Richard Schahinger of the Department of Primary Industries, Parks, Water and Environment (DPIPWE) and and other members of the Threatened Plants Tasmania group, we stopped at a small soak in the Tom Gibson Nature Reserve to look for ephemeral plants. It was not long before the keen and experienced eyes of Richard sighted the Slender fanwort.

The Slender fanwort (Aphelia gracilis) can be easily confused with sedges. In particular, the common Tiny Flatsedge (Isolepis levynsiana), which we found co-occuring with the Slender fanwort, has flower parts that look very similar to the spike of the Slender fanwort. However, upon closer examination, the hairy bracts of the Slender fanwort immediately distinguish it. Moreover, the Slender fanwort is often brownish-pink in all parts of the plant.

Aphelia pumilio (Dwarf Fanwort)

I was not quite as fortunate with the Dwarf Fanwort, managing only to find patches which had already dried out and died. However, Mark Wapstra had found some fresh specimens at another site in his earlier plant hunt and showed it to those around. It was as curious in real life as it looked in photos and illustrations.

Dwarf Fanwort is instantly recognizable by the pompous spikelets that practically dominate the plant body. Sometimes the flowering stalk may be taller Even if the flowering stalk. There is nothing else like it in Tasmania and there certainly is no sedge with such a disproportionate spikelet/plant body ratio!

I haven’t had the chance to ask Mark, a co-author of the Little Book of Common Names for Tasmanian Plants what prompted them to call Aphelias fanworts. Perhaps they likened the floral parts to an open fan. I’d prefer to think that the Aphelias are called fanworts because diminutive and inconspicuous as they may be, they have that inexplicable power to make fans of plant lovers, as they have of me.

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.

What do you do when you are faced with something that is an unbearably adorable?

There is little recourse but to fall head over heels for it.

For many people the object of adoration may be a puppy, a kitten, a small fat chirping birdie, or some other cuddly animal. Seldom have plants been viewed as cute or adorable.

Yet everytime I encounter a plant in turfed perfection (being small accentuates this), with scapes of flowers or fruits pointing heavenwards, I start experiencing a fluffy feeling inside similar to that a kitten evokes in me in it performs it’s cutest antics. I’d call this the unbearable adorableness of turfed existence.

One of the many plants that fall under such a category is the Hairy Bristlewort (Centrolepis strigosa) (Just so you can have a feel for how small bristleworts can get, the picture above was taken with a $2 Australian coin which is roughly 2 cm in diameter).

I made my first acquaintance with this common plant a year ago in the Northwest part of the state and I have been finding it everywhere since. But everytime I see this little plant I cannot help but want to take a picture.

And as you would no doubt have surmised, I don’t stop myself…

Despite having visited the Royal Tasmanian Botanical Gardens more times than I care to remember, there is always something new there to see.

About two weeks back I was looking around one of the native plants section and found an interesting heath (Epacris) planted there.

It was the double pink-form of the common heath (Epacris impressa). Unlike the normal Common heath with it’s long trumpet-like flowers, this interesting form shorter corollas and rose-like petals, not unlike the widely cultivated double rose-form  Camelias we see in many gardens.

How exquisite! I wonder how this form came about.

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.

Caladenia carnea (Pink Fingers)

One of the largest orchid genus in Tasmania must be Caladenia, of which the island (including the smaller islands off the state) boasts 36 species. That makes it one of the largest genera of plants in Tasmania.

While members of the Caladenia are a morphologically diverse, they are readily recognizable by gist in the field.

There are at least 2 different forms: the small flowered ones are more commonly known as Finger orchids while those with long sepals and petals are usually known as Spider orchids.

Just in the bush around Hobart alone, at least a third of the 36 Caladenia species occur. One of them, the small flowered Caladenia sylvicola (Forest fingers), is an endangered orchid with very few known records.

C. fuscata (side view showing streaks on column)

According to The Orchids of Tasmania, the species was first collected in 1992 in a locality near Dynnyrne, under heathy Silver Peppermint (Eucalyptus tenuiramis) forest. A larger colony was later found in 1994 in the same vicinity.

In my visits to the area I have found two species of Caladenia co-occurring there. These are namely Caladenia carnea (Pink Fingers) and C. fuscata (Dusky Fingers).

In the species key given in Orchids of Tasmania, C. sylvicola is distinguished from C. fuscata and C. carnea by the lack of the pink, red or purplish bars that streak the column.

C. sylvicola? (streaks absent on column)

On the 16th October 2004 I was botanizing in a bush near the Waterworks Reserve and I stumbled on a strange looking Caladenia, growing amongst a vibrant population of C. fuscata.

This mystery orchid was totally white and had yellowish calli (protuberances found inside the column of many orchids). There was only one plant and I figured it was just a white form of either C. fuscata or C. carnea.

In the Orchids of Tasmania book, the description for Caladenia sylvicola was the closest match to what I had found.

Caladenia sylvicola (Forest Fingers)? 16 Oct 2004

If my identification is correct, that would the first time it has been seen for over a decade. Apparently, the esteemed photographers from the Up Close website had also encountered a similar orchid which they left unnamed. Unfortunately, they left no date or location on their website as to when they photographed the flower.

In any case, I did not see the presumed C. sylvicola for another 5 years, despite serious searchs.

Then this year, on the 22 Oct I spent an evening orchid hunting around the vicinity and spotted a single ghostly white orchid. It has a slightly damaged dorsal sepal but in all respects was similar to the one I had seen half a decade earlier.

Caladenia sylvicola (Forest Fingers)? 22 Oct 2009

Again, this single specimen was co-occuring with large number of C. fuscata (Dusky Fingers). I also know from past encounters that the area is also a haunt of C. carnea (Pink Fingers).

This begs a question.

Could C. sylvicola just be an aberrant albino or just a pure white form of C. fuscata or C. carnea?

C. carnea tends to be a bit larger and taller than C. fuscata and C. sylvicola. C. carnea also has the ability to bear two flowers per scape, a feature not observed in C. fuscata and C. sylvicola. It is unlikely then, to be confused with C. sylvicola.

With C. fuscata however, other than the pink bars on the column and the coloration of the petal, sepals and calli, there were little other morphological features differentiating this species and C. sylvicola.

In the aspects of stature and calli arrangement, the two were indistinguishable.

I did not collect the single specimen of the presumed C. sylvicola as it would be a legal offense to collect threatened plants. However, I did take a long hard look at the calli of both species in the field and could not discern and any differences in the arrangement of the calli. With the exception of colour differences, both had two rows of calli extending into the column in a similar fashion.

C. fuscata - pink and white form side by side

Also, C. fuscata in the area exhibited a wide range of colour from deep pink to white, with white ones occurring at a much lower frequency.

In the latter case, there are red/purple streaks marking the labellum and column as with the typical pink forms.

The idea that C. sylvicola may be a totally white form of C. fuscata may not that hard to believe.

I use the example of an orchid of another genus, Chiloglottis. The Small Bird orchid (Chiloglottis grammata) is typically dark purplish brown but greenish purple and pure green forms exist. Yet by virtue of their calli patterns the green and dark purplish-brown forms are all called Chiloglottis grammata.

Another argument would be that the two times I have sighted the presumed C. sylvicola, they popped up in the middle of a healthy C. fuscata population, the latter species displaying different shades of petal and sepal color ranging from deep pink to white. It is therefore easy to conceive of C. sylvicola as just being at the farthest extreme of the color and pattern themes of C. fuscata.

Other questions arise from this mental workout.

If C. sylvicola is a real species, could it have evolved from C. fuscata, perhaps by mutation? If so, C. sylvicola doesn’t look like a species that is doing too well.

What these speculations need are scientific studies using a combination of morphological and molecular analyses. Some workers have already developed, from some species of Chiloglottis, certain DNA markers called microsatellites. These microsatellites, if they can be developed for Caladenia, can be useful in finding out the relationship between C. sylvicola, C. fuscata and C. carnea.

There really is much we have yet to know when it comes to orchids. But then again, isn’t it the same for just about anything?

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.

Ozothamnus antennaria (Sticky Everlastingbush)

In Tasmanian botany I was taught the concept of a cline, where a plant species seems to metamorphose into another species along an environmental gradient. In other words, what is considered a plant species at one end of a environmental continuum (eg, the base of a mountain) shows continuous morphological variation and seems to become another species as one goes up a mountain.

The most quoted and classical example of this would be that of the eucalypts, where you might see the Yellow Gum (Eucalyptus johnstonii) grading into the Alpine Yellow Gum (Eucalyptus subcrenulata), which grades into the Varnished Gum (Eucalyptus vernicosa) along some mountains in Tasmania.

I have often wondered how the concept of clinal variation might apply to other Tasmanian plants.

Ozothamnus rodwayi (Alpine Everlastingbush)

An example I had in mind was of the Tasmanian Everlastingbushes (Ozothamnus spp.).

In particular, the high altitude Sticky everlastingbush (Ozothamnus antennaria), Alpine everlastingbush (O. rodwayi) and Mountain everlastingbush (O. ledifolius) seem to exhibit morphological features that makes it easy to imagine that these species somehow evolved from one to the other or graded from one to the other along some sort of a environmental gradient.

It is easy to imagine the leaves of O. antennaria (which grows at slightly lower altitudes from it’s two relatives) becoming smaller and the flower heads getting more compact until it becomes something like O. ledifolius, the morphology of O. rodwayi being intermediate.

Ozothamnus ledifolius (Mountain Everlastingbush)

Not sure if this betrays any relationships: O. ledifolius smells vaguely of cinnamon spice and O. rodwayi seems to have a similar, albeit fainter smell. O. antennaria has the faintest smell last I took a sniff.

In any case, the idea of a cline in the everlastingbushes could be fallacious. But afterall, all good science starts with a conjecture, insane as it may seem. It would really be an interesting hypothesis to test using molecular methods, wouldn’t it.