Tuesday, 17 January 2017

Pretty, leafless, and not a guinea worth

The genus name Hibbertia honors George Hibbert, a lover of plants and patron of botany. George was a fellow of the Royal Society and the Linnean Society in London, and purchased collections of preserved plants (herbaria) as well as funding collecting trips to, for example, the Cape of Good Hope in southern Africa.

If we look at this particular species (Hibbertia dilatata, above) from the Top End of Australia and compare it to those more usually associated with the name George Hibbert, you'd be looking for leaves and perhaps more yellowish flowers. The one below is your more 'typical' Guinea Flower, from Ku-ring-gai National Park.

And this one from our front yard, Hibbertia stellaris, a native to Western Australia, stretches the yellow to orange, but at least it has leaves.

There are around 250 species of Hibbertia in the world, the vast majority found in Australia but with some in Madagascar, New Guinea, New Caledonia and Fiji. Northern Territory has 50 species, with 28 of these added as new in 2010 (by Helmut Toelken) and five moved across from what used to be called Pachynema, a mostly leafless groups of plants.

Flowers of the genus Hibbertia can be yellow, orange, pink, white or red, but many species do have yellow flowers - hence the common name, Guinea Flower. The flower from the Northern Territory has white to creamish petals, but more often flushed with pink. This flower has three remaining of the five petals. Still pretty, but not conjuring up a guinea.

Pachynema means thick filaments. Filaments are the stalks that hold the sacks of pollen aloft in a flower, and these flowers have ring of stumpy bottle-like filaments just inside the petals, as you can see here (in yellow).

Like other species previously called Pachynema, Hibbertia dilatata has no leaves - although some species in that group have leaves only at the very base of the plant. The stems of such plants are photosynthetic (green) and usually flattened. In this case, very much flattened and looking like a long strap-like leaf.

As a gratuitous aside, this particular specimen was growing in a recently burnt area near Greenant Creek, in Litchfield National Park. The ants in question were nesting in the leaves of a nearby Red Paperbark (Lophostemon lactifluus); illustrated, with ants, below. You can bite their green bums off for a tangy treat.

Tuesday, 10 January 2017

Xanthostemon is a hot plant

In July 2003 I visited New Caledonia, an island of botanical treasures. I was there to collect red algae (one of those treasures) in the mountain streams, including the Chute de La Madeleine, about 100 km south of the capital Noumea. (In the foreground of this picture I took of the 'chute' is the New Caledonia Corkwood, Retrophyllum minor, a rare podocarp restricted to this area).

It just so happens this is also where some of the more intriguing plants hang out, include relatives of familiar Australian plants in the families Myrtaceae and Proteaceae. The soil is rich in nickel and other metals, giving it a deep red hue and the classification ultramafic (meaning low in silica and high in minerals).

This was one year before I bought my first digital camera but some years ago I scanned just one of the plant photos, using it as a reminder of that spectacular flora. This is the photo, of Xanthostemon aurantiacus. (You can also see this species in the Southwest Pacific Island Collection, down by Nymphea Lily Lake in Melbourne Gardens.)

Ferdinand Mueller described the genus Xanthostemon in 1857, from material collected in tropical Australia. So it was with some pleasure in October 2016 I saw and photographed Xanthostemon paradoxus, the very species Mueller collected, during a warm walk through Litchfield National Park (which is curiously about as far from Darwin as Chute de La Madeleine is from Noumea).

Mueller found his Xanthostemon pardoxus near the Victoria River, further east, and the species is relatively common across the top of Western Australia and Northern Territory. There are now known to be 45-50 species of Xanthostemon, 13 or 14 in Australia and the rest distributed throughout Pacific Islands and nearby south-east Asia.

All species have a woody fruits and mostly yellow stamens (the stiff brush-like parts of the flower topped with the pollen bearing anthers). Xanthostemon paradoxus carries the rather odd common name of Bridal Tree as well as various names from local Indigenous languages, including sometimes the apparently cross-cultural, Northern Penda,

Back in the 1950s, this species was discovered to be a 'uranium accumulator' and just recently it was mentioned again as a plant that may warrant further investigation for biogeochemical prospecting. The ease at which the uranium was washed from the leaves led to some concern in the original study that the relatively high amounts found in leaves might be due to contamination at the site rather than the plant drawing uranium up from the soil.

In terms of the species being used to locate underground deposits, presumably this also depends on whether Bridal Tree favours areas rich in uranium or simply accumulates the mineral when growing in uranium-rich soils, Do you simply map where the plant grows or do you have to grind up the leaves of each population to find out whether it's growing above uranium? Alternatively you might 'mine' the minerals directly from the plants themselves, which may be possible one day.

In any case, a brush of yellow anthers might be a hint that yellow rock is nearby. But to finish, three pictures of a third species of Xanthostemon, only found in the Northern Territory, and here nestled beside Tolmer Falls in Litchfield National Park. It's called Xanthostemon eucalyptoides, although in leaf, apart from the lack of black hairs, I would have named it Xanthostemon 'angophora-hispida-oides'...

Tuesday, 3 January 2017

Not much of a view from this Atalaya

This not a grass, a sedge or a rush. And it's not a member of some obscure plant family related to those tufted 'monocots'. In fact its a very small tree. Sort of.

Back in late October I spent a few days in Darwin including a steamy day in Litchfield National Park with a bunch of botanic garden bosses, including the head of the George Brown Darwin Botanic Gardens, Bryan Harty. and lead by the local Gardens' seed collector and conservation botanist, Ben Worth.

Through the haze and dripping sweat we saw plenty of fascinating Top End plants. I'll feature a few in coming weeks but I want to start with something very unprepossessing, Atalaya brevialata.

Never heard of it? Neither had I. Atalaya is a city in Argentina, a province in Peru, a castle in South Carolina and a golf club in Spain. Oh, and a plant genus of a dozen or so species in the family Sapindaceae (the soapberry family, including lychees and, these days, maples). 

There are nine species of Atalaya in Australia, all of them found north of Sydney. The others occur in southern Africa and Asian countries to the north of Australia.

'Atalaya' is a Spanish word meaning a tower of some kind, giving an elevated view.  This fits nicely with most descriptions of Atalaya (e.g. PlantNet), which say it's a genus of trees and shrubs - you can see things from trees and larger shrubs. Other genera similarly described are Eucalyptus and Acacia. So that's what you expect, something like a gum tree or a wattle in stature.

But Atalaya brevialata is hardly even a small shrub. The Flora of the Northern Territory describes it's growth habit as suffruticose, which means woody and perennial (that is, long-lived) at the base but predominantly soft and herb-like. So it's a tree or shrub up to, and perhaps just a centimetre or two above, ground level but to all intents and purposes - to you and I - it's grass-like. The above-ground bits are in fact annual - they die back each year (to the 'tree' underground).

So as the top picture shows, it more closely resembles a grass, at least from a distance. It's hard to find in the first place given that it grows among true grasses. Once spotted and you get your eye in it's then hard to miss. Close up you notice, perhaps, that the veins on the leaf are not all parallel like grasses but are net-like and, in relief, lined up in rows at an angle from the mid-rib.

Describing it as a tree or shrub might be technically correct but not very helpful for identification. And we need to find and identify it because it's rare enough to be under threat of extinction. That why Ben has been collecting seed of Atalaya brevialata for the George Brown Darwin Botanic Gardens conservation seed bank, part of the Australian Seed Bank Partnership.

It only grows at and near where we saw it - somewhere near Litchfield National Park. Let's take a closer look at it, by getting down to ground level...

The species name means a short, flattened something, and our plant is rather short, with these flattened leaves. Actually, the name refers to the very short 'wings' on the seed, which are so small I didn't notice them. A bit like the plant itself. .

The flowers are small, fluffy (due to tiny white hairs) and ... well, a cluster of them looks like this: 

These pictures show just a handful of the 300,000 plants of Atalaya brevialata thought to exist in nature, which sounds like a lot. But they live in five small populations, all within a total area of 7-8 square kilometres. So a fire of the wrong kind, land clearing or perhaps a disease could easily wipe out the species, forever. Getting seed into the seed bank is an insurance policy for it's long term future.

Tuesday, 27 December 2016

Lone orange blossom in the Victorian rainforest

To end the year (my eighth-and-a-bit year of Talking Plants), the story of a plant bearing small white blossoms with a citrous bouquet, and clinging desperately to the trunks of a few rainforest trees in East Gippsland.

The Orange Blossom Orchid, Sarcochilus falcatus, is confirmed as a native in Victoria by a small number of plants attached to rainforest trees in Howe Range, east of Mallacoota in the State's far east. Their location is not far from NSW, where the species is not uncommon along the coastal strip right up to southern Queensland and (thanks David Banks, my Sydney colleague, for confirming this big disjunction) also around the Atherton Tableland and Mt Lewis, up Cairns way.

You'll see other records for Victoria, some no longer current. These days it is extremely rare in Victoria due 'to clearing of its habitat for agriculture', and even its meagre mapped distribution in East Gippsland may overstate its true range due to a little assisted dispersal by local humans.

For example, according to Gary Backhouse, Bill Kosky, Dean Rouse and James Turner, in their 2016 e-book, Bush Gems: A Guide to the Wild Orchids of Victoria, Australia a remnant population near Cann River was lost during a flood in the 1980s. Whether this population existed pre-European settlement is disputed, by some.

Over the border Orange Blossom Orchid usually grows on the trunks of Blackwood (Acacia melanoxylon), or rocks. In Victoria, according to VicFlora, it is more often found on Eucryphia moorei, the Eastern Leatherwood but it is also (Gary Backhouse and Jeff Jeanes The Orchids of Victoria; 1995) found on Blackwood, Lilly Pilly (Acmena smithii) and, apparently after plants fall from tree trunks, on rocks and tree ferns.

Tony Bishop (Field Guide to the Orchids of New South Wales and Victoria, 2nd edn; 2000) illustrates three growth forms from New South Wales with variously coloured stripes on the lip and odd odors, including one 'resembling freshly cut potatoes'. In Bush Gems the Victorian populations are said to include a mountain growth form with purple markings on the chin-like protrusion (the spur) of the winged 'lip' (labellum). Or perhaps a lowland form without the markings, depending on your altitudinal perspective.

Either way, these and other variants may, or may not, require taxonomic recognition - as might other variants with variously coloured and shaped floral parts. I couldn't see any unusual purple tints on this home-grown specimen other than stripes on the back of the flanking petals (and the orange blossom purfume didn't seem to be infused with potato).

There are 20 or so species of Sarcochilus, collectively called the butterfly orchids, with 16 species in Australia and New Caledonia (there are no 'true' Sarcochilus in New Guinea according to David Banks). We have only two in Victoria - Sarcochilus falcatus and Sarcochilus australis. The other species - australis - has flowers with narrow, green or brown, outer segments (not broad and white as in falcatus).

These two species are unusual in the south-east corner of Australia. Of the nearly 370 to 400 species of orchid known from Victoria (of which 327 are formally named and described) there are only another two that grow on trees or rocks (ephiphytic or epilithic, respectively) - the rest are ephemeral ground orchids with underground tubers.

As you travel north the epiphytic/epilithic orchid flora become more prevalent and more diverse. Here in Victoria we celebrate these northern immigrants or remnants as we celebrate the wedge of warm temperate rainforest extending into East Gippsland. (Sarcochilus australis also finds a home nearer to Melbourne and in the Otway Ranges, but the other three - including our Orange Blossom Orchid -  are all confined in Victoria to East Gippsland.)

The pictures in this post are from a cultivated plant purchased recently at the Australian Native Orchid Society annual show, and flowering at my home in early October. Its origin in nature is unknown (to me).

Tuesday, 20 December 2016

The unappetising Capeweed

If you are an Australian, your first reaction to this image is likely to be one of disgust and frustration. Capeweed is an irritating incursion into many an suburban lawn, and an expensive - and most would consider an unattractive - weed of crop and grazing land. Thankfully it should fade from view in our country by Christmas Day.

On the other hand, in its native homeland of South Africa, Arctocheca calendula is considered a 'versatile ground cover that can be used in a garden for holding soil and for a colourful display'. That it probably does, in Victoria, and much of the rest of the world, as well.

If you look beyond the weed designation you'll notice a plant with incised, lyre-shaped leaves, each gently toothed and mildly hairy. The underneath of each leaf is softly hairy, what we call tomentose

The flowerheads are a cluster of small flowers, like most daisies, with the outer ones sprouting a papery, two-toned yellow petal. The inner flowers are very Melbourne - black. You can see the pollen containing anthers sticking up above some in this picture.

It's hard to do. To appreciate's its unique combination of characteristics. To marvel at what makes it a distinct species. Even in its native habitat in South Africa it frequents disturbed soils, carrying the common name of Capeweed there too, as well as the more neutral Cape Dandelion.

There are four or five species of Arctocheca, all from South Africa and Mozambique, with three of them naturalised in Australia and in Victoria. In VicFlora, Capeweed is described as a 'widespread weed of lawns, cultivated areas, pasture and other disturbed sites'. It has a similar distribution, I gather, in all southern Australian States, with the earliest reports from the far south-west, near Albany, in 1834.

As this map from VicFlora shows, it's hard to miss. My photographs are from a park in and nature strip in the suburbs of Melbourne, taken in early October. It could be anywhere - well at least anywhere there has been some disturbance and a little moisture in the soil - and almost anytime, although it fades in time for Christmas, ready to flourish again in autumn.

In South Africa it spreads by overground stems called 'stolons' or runners, and by seed. In North America, Capeweed is usually is sterile but spreads readily through runners - rarely, the plants are fertile and then considered 'highly invasive'. Here in Australia it depends, apparently, on the particular variant and the location.

While clearly all over the place, and all over the globe, it seems to still have some potential to expand its range. In California is is considered a weed 'with the potential to spread explosively' and in Italy, in early 2016, it was announced as an 'emerging invasive species'.

So it is here to stay. It can displace native species, sometimes already under threat of extinction, but in lawns and disturbed sites near towns and cities, well perhaps it's best to learn to like it a little. 

Bees and apiarists like it. While it can be eaten by stock*, young plants may poison and a high intake will taint milk. Sadly you can't eat it: Capeweed is generally considered a poor and potentially disagreeable food for humans. (Unfortunate, because as you rip it from your lawn you might notice a red or purplish tint to the base of the plant, presumably coloured by anthocyanin, a water soluble chemical you find in various 'good for you' plants like beets and trendy purple brussels sprouts.)

Best to simply botanise, or romanticise.

*Dan Murphy (28 December 2016) notes that when he was in South Africa he saw dassies (a hyrax/badger kind of creature) grazing on them, and eating the 'crown'.  

Tuesday, 13 December 2016

Same-sex Wedding Bush adds up

The scrub at Cranbourne Gardens has great conservation significance but for much of the year it can seem rather drab - unless you find wallabies, bandicoots and the occasional koala interesting. Which of course we all do.

In sprinter (these pictures were taken in late September, pretty much at the end of the flowering season), one plant seems to shock the bushland into action, being followed by native heath, tea-trees and more cryptic ground orchids. None of them are as floriferous as the Wedding Bush, Ricinocarpos pinifolius. It has a lot of flowers and I'm assuming the Wedding allusion in the common name is because in flower this bush is very white.

Wedding Bush is relatively common in coastal, and near-coastal, areas of Victoria, then northward to about mid-Queensland and southward to Tasmania.The genus Ricinocarpos is a mostly Australian one, with 15 species native to this country and one only found in New Caledonia.

It's in the family Euphorbiaceae, which means that it can look just about like anything and have flower arrangements that are as weird as you want. At least this one has petals and leaves. The leaves are like a pine-needle, hence the species name 'pinifolius'. The flowers look like a daisy, from a distance at least.

Close up you can see the flowers have five, crisp, white flaps - the petals - hiding five triangular green bits that are the sepals, or calyx. Inside, these flowers at least, is a small fountain of male parts, the stamens.

The flowers are either all male or all female, with each cluster typically containing one female flower and three to six male flowers. I didn't see any obviously female flowers in my photos so I'm assuming they have already faded for the season - they usually open in advance of the males, although occasionally there is a second wave of female flowers.

In a study published in 1989, a population of 54 plants were measure for their gender mix. On a scale of 0 (all male flowers) to 1 (all female flowers) the Wedding Bushes were 0 to 0.68, with a mean of 0.16. That is, plants tend to have far more male flowers than female flowers, and sometimes no female flowers at all.

In case you are struggling with the maths, or more likely my clumsy explication, it seems that while a typical cluster of flowers includes one female and 3-6 males, some (to all) clusters may have no females (no plants or clusters are entirely female flowered). Consequently the mean (or middle) ratio of female to male flowers in a plant is not 1:4.5 but 1:6.3... Of course this was one study, on one population, and the authors caution against too much generalisation.
To bring it back to specifics, was my plant a very blokey plant or just past its female prime? Dunno. In any case, apparently this variable mix of genders on a plant works, with most flowers setting seed and even all-male plants contributing their genes to the final outcome.

Tuesday, 6 December 2016

Do fungi get the winter blues in D?

The modern study of genetics and DNA has shown that mushrooms (and other fungi) are more closely related to us humans than they are to plants. Here you see a mushroom and a mycologist (a fungal expert, in this case Dr Tom May) getting to know each other in the Melbourne Gardens of Royal Botanic Gardens Victoria.

This relationship makes some sense because fungi don't produce sugars using sunlight (i.e. they don't photosynthesise), their cell walls contain chiton rather than the cellulose found in plants (and chiton is found in the hard outer layer of insects), they contain proteins similar to those found in animals, and ... they can produce vitamin D.

Unlike humans, fungi don't seem to suffer from vitamin D deficiency but perhaps that's because the mushroom medical service is less interventionist. You can find reference to up to 80% of the humans in the USA being deficient in vitamin D. Whatever the real human deficit, vitamin D is certainly needed to allow calcium to be absorbed and turned into bone. Vitamin D is also implicated in keeping your brain healthy and its absence has been linked to various diseases and ailments.

I'll put my cynicism aside, although I'm tempted to put out a call for anyone who has had their vitamin D levels tested and been told they are sufficient. Let's start with the premise that humans need vitamin D for a healthy and worthwhile life, and that they can produce it from the action of sunlight on their skin.

So if you need more vitamin D you can risk skin cancer by exposing your surface to the sun, harvest the livers of cod (allowing them to ferment for a year if you are a traditionalist) or encourage some (edible) mushrooms in your lawn and then (if really edible) eat them. OK, there are few other sources of this vitamin but they are not as interesting.

Back in 2013 that ever reliable source of information, the UK Daily Mail, suggested we place our store-bought mushrooms out in the sun for half an hour to give us a dose equivalent to a tablet or two. Or if you prefer the view of a 'respected Australian scientist', Professor Rebecca Mason, head of physiology at Sydney Medical School, said (also in 2013) three or four small mushrooms left unwrapped on a plate in the 'midday summer sun' for two hours (longer in winter) will produce enough vitamin D for your average humans daily needs.

Another way to create food rich in vitamin D is to allow fungi to 'contaminate' plants. That contamination could through mutually beneficial relationships such as mycorrhizae on plant roots - although presumably the fungi would have to fruit in the open air so that they produced some vitamin D for the sharing. There is some research needed in this area.

Although mushrooms and other fungi produce only one kind of vitamin D - called D2 - medical studies have (apparently) shown that the fungal dose can be as effective for humans as tablets with both D2 and D3. (Vitamin D1 is apparently less common and/or less important, as are D4 and D5.) Cooking doesn't damage the chemicals and may even help in their uptake.

All very interesting and another part of the evolutionary history shared by fungi and humans. What we need now is research into the well-being of those poor mushrooms produced in musty dark cellars.

Images: The plate of edible fungi is from a restaurant in Edinburgh, visited in September 2006. Here is the owner proudly showing me what would end up in my (very nice) pasta dish. I don't know that the mushrooms and other fungal fruiting bodies produced in this region would get much sunlight even when grown above ground.

Tuesday, 29 November 2016

Stachyurus a veil of dubiously sexed flowers

Using my misleading 'from a distance' identification skills I thought I could see a close ally of Garrya elliptica - the Silk Tassal - ahead as I walked through Burnley Gardens in late September. As I got closer it clearly wasn't but I struggled to remember what this plant was called, even its plant family (which can be a good way to narrow down the options, sometimes).

It's a species I do know but as Stephen Harris, from University of Oxford, tells us, this is one odd plant. So odd that its genus, Stachyurus, requires its own family, the Stachyraceae. In his Horticultural Flora of South-eastern Australia, Roger Spencer describes the dangling flowers of the Spiketail as 'looking like ears of wheat'.

Four of the eight species are found only in China (+/- Taiwan I should add), including this one, which I'm pretty sure is Stachyurus chinensis. In nature this species is widespread at the edge of forests, and like that other Stachyurus species found sometimes in Australian gardens, Stachyurus praecox from Japan, it begins flowering before the leaves appear.

Compared to Stachyurus praecox (and other) species, Stachyurus chinensis has rounder leaves, a longer chains of flowers, and the male and female bits held within the petals. Although Christopher Grey-Wilson and Phillip Cribb in their Guide to the Flowers of Western China note that sometimes these two species are considered one and the same.

The species name 'praecox' refers to its early flowering, making it a good indicator of sprinter. This species, from China, flowers later and was powering through to sprummer (mid-spring) when I saw it in late September.

Originally Stachyurus was included with Camellia in the Theaceae, and later considered to be close to the Hamamelidaceae (with things like Witch Hazel, but also the Winter Hazel, Corylopsis, which has a drooping chain of flowers) but it turns out to be more like the succulent with rotten-meat-smelling flowers, Staphylea, and an odd little family from middle Americas called the Crossosomataceae.

Anyway, a very 'special' group of plants, and the genus name 'stachyurus' refers - in ancient tongues - to the most distinctive feature of the flowers, their arrangement into a dangling tail. 

In nature, apparently, flowers can be female-only or have fully functioning male and female bits. However even the ones that look like both bits are working and active, produce mostly pollen and behave like males. So out in the wild bees and flies are essential for cross fertilisation and seed production.

The plants I observed in Burnley Garden seemed to have flowers with juicy male and female bits, and then further back up the flowering tail, fruits that seemed to be setting.

All that hidden within a veil of flowers caught in the morning sun.