Tuesday, 24 April 2018

South African Pelargonium in healthy shades of pink


This attractive plant in the South African collection at Melbourne Gardens sports a label identifying it as Pelargonium sidoides. When I looked for more information about the species I wondered if it was a misidentified, or mislabeled, Pelargonium reniforme.

The two species are closely related. Indeed Pelargonium reniforme was originally, back in 1860, considered to be but a variety of Pelargonium sidoides. Pelargonium sidoides is said to have smaller, darker flower, almost black in colour. In my photos these flowers don't look black - although they have a darker sheen in real life.


Luckily, as it turns out, our census says we have both species growing in the Melbourne Gardens, so I checked out presumed localities for Pelargonium reniforme and could confirm that we do have both species. This is the flower of what I'm taking to be Pelargonium reniforme on the left, with the darker, smaller flower of Pelargonium sidoides on the right. (Notice by comparing the flowers in the picture above with the right-hand flower below, how even this different setting 'changes' the colour.)


There are also reputed differences in leaf shape with those of Pelargonium sidoides heart-shaped and those of Pelargonium reniforme, consistent with the species name, kidney shaped. There is not much in it though, assuming I/we have the taxonomy and nomenclature correct! The first image here is reniforme (kidney-shaped), the second sidoides (heart-shaped).



'Heart-shaped' compared to 'kidney-shaped' usually means a bit pointier at the far end, but that's not obviously the case here. The leaves of what we are calling sidoides do tend to be a little more folded or creased half way along and near the stalk, as you can see in this next photo I took of leaves from both species, with Pelargonium sidoides on the right. But maybe we have cultivars, crosses and intermediate varieties...


The two species are from southern Africa and reasonably drought tolerant. Pelargonium sidoides is widely distributed across South Africa, from the Eastern Cape through to Johannesburg, and extending into Lesotho and Swaziland, while Pelargonium reniforme is restricted to the Eastern Cape region only. The latter species is under some threat from unsustainable collecting, even though it is widely available in horticulture - not so much threat of extinction but with the potential to disrupt local ecosystems.

Both have medicinal uses, to varying degrees, which is why Pelargonium reniforme is over harvested. Pelargonium sidoides is better known in contemporary medicine but each of them has a long history of use in traditional treatment of stomach and liver ailments, as well as respiratory complaints.

Extracts from the bitter roots of Pelargonium sidoides, traded as Umckaloabo (German) or Rabassam (Afrikaans), have been shown in clinical trials to reduce the severity of symptoms and the duration of acute bronchitis. The efficacy of Pelargonium reniforme, however, is disputed and a 2012 study confirmed it lacks a key active chemical called umckalin.


So while it may not matter too much in our garden which species is which, as with all taxonomy there can be important implications. For us, both species are attractive when in flower at the tail end of summer and in early autumn. I quite like the velvety textured leaves too, wishing I'd found them before talking textures recently with Jonathan Green on the Last Half Hour of Blueprint for Living (ABC RN). I could have told him these leaves are described as 'densely pubescent', which they are, and that with a hand lens I could show him some additional differences between the species in the kinds of hairs that create this pubescence. But possibly that wouldn't have been great radio.

Tuesday, 17 April 2018

Deadly breakfast spread from Medusa's head


In Greek mythology, Medusa has a pair of fetching wings and a hairdo of snakes. That is until she looses her head. Unlike most Greek monsters this kills her but the severed head leads to various consequences such as children arising from spurted blood and viewers of the head turning to stone. And so on.

So when a plant is called Medusa's Head you are on the look out for something gruesome, or perhaps reptilian. This is what the female flowers of Euphorbia caput-medusae looks like.


I could read into these flowers a hairdo of some kind but Plantz Africa has a far better (and correct interpretation). This plant from the Cape region of South Africa has 'multiple serpent-like stems arising from a short ... woody stem'. So it this habit that gives this plant both its species epithet and common name.

As with many of the world's garden plants, this species was described from Europe (in 1753) by the famous Swedish biologist Carl Linnaeus. It had reached the Netherlands in 1700 and was grown by Linnaeus's friend and previous employer George Clifford, a director of the Dutch East India Company. Hence the reference to a very European mythical figure rather than one from Africa.


The specimens photographed here are in our South African collection at Melbourne Gardens (in January 2018) and only a few years old. A mature plant near Cape Town, where they are common, can reach a metre across.

This is a good garden plant for a warming, drying climate. It's succulent, so it can hold water in its stem, and the leaves are rather small, so they won't loose much water. The whole plant is photosynthetic (green) so it will take maximum advantage of sunlight to produce sugars (probably taking up carbon dioxide at night, but that's another story).

Let's take another look at that flower. Like most Euphorbia, or spurges, the 'flower' is peculiar rather than pretty.


The whole thing is called a cyathium. There are five fan-shaped bracts radiating like hands from the outside of the flower. Each of these bracts has a fringe of glands. In the middle of the cyathium is a single female flower surrounded by six small male flowers - if you look carefully you'll see the yellow pollen at the tips of a pair of anthers on top of a single stamen rising out of each male flower. 

Bees visit the cyathia, but there is a twist to this. Apparently, the honey produced by bees visiting Euphorbia species is poisonous to humans but not bees. The sap of Euphorbia contains some nasty chemicals and it is these, it seems, that end up in this unwanted form of honey called Noors. 

In South African mythology there may not be a medusa, but there is a 'deity' called Gao!na who turned himself into honey 'to poison a man who had displeased him'. The honey he became, Noors, had its origins in flowers such as those of this exotically named head of snakes.

Tuesday, 10 April 2018

Lorikeets find their manna in Cranbourne gums


Back in February - in its first week - I joined a group of staff and volunteers at our Cranbourne Gardens to count birds. Actually not so much birds as bird calls (mostly), each representing an individual bird of a particular species.

After twenty minutes we had tallied 12 species (I say 'we' but let's be honest, 'they'), quite a few less than the previous survey where more than 20 had been heard or seen. One species that was more common on this occasion was the Musk Lorikeet, possibly displacing other birds with its raucous behaviour.

I'm more familiar with the Rainbow Lorikeet, which is in a different genus and more common. The Musk Lorikeet has more green with a lovely pale blue cap on its head. It's widespread in south-eastern Australia, just not as common as the Rainbow. At Cranbourne it is attracted by the flowers of the local Manna Gum, Eucalyptus viminalis subspecies pryoriana, and this year the gums were particularly floriferous.

The perfume of the Manna Gum was described to me as smoky honey. There was none of that early in the morning in early February but there were plenty of flowers, like this, attracting the noisy lorikeets. The flowers contain a rich nectar reward.


As to the real manna of the Manna Gum, that's a sweet, white material exuded from some leaves and stems in response to insect nibbling (the manna of the bible is thought to have been from a Tamarix, again bug induced). It is also eaten by birds, and mammals, providing a year-round food source when trees are not in flower. Flower time, though, is when there is more food and more feeding birds.

Our variant of the Manna Gum, subspecies pryoriana, sometimes called the Gippsland Manna Gum, is distinguished from others in the species by its bark - rough bark on trunk and main branches - and its buds and fruits - mostly in groups of three. These characters are a little blurry at the edges, and if you are keen on sorting out your local Manna Gum species you should consult VicFlora and perhaps Kevin Rule's key in the 2011 issue of the Royal Botanic Garden Victoria's scientific journal Muelleria.

The Gippsland Manna Gum is not uncommon in Victorian woodlands near the coast from Geelong to Lakes Entrance, reaching 15 metres tall at most. The tallest Eucalyptus viminalis (subspecies viminalis), in more fertile soils on mountain ranges, can be in excess of 80 metres.

Most of us know the Manna Gum as 'the koala tree' because the leaves are one of their favourite foods. We get koalas in our trees at Cranbourne Gardens, although fewer of them than Musk Lorikeets.


You can see in this picture the willow-like appearance of the leaves, although perhaps shared with many other eucalypt species, which inspired this species botanical name 'viminalis'. The subspecies, is after Canberra-based eucalypt botanist, Lindsay Pryor (1915-1998).

In case you are wondering, I didn't see, let alone photograph, a single Musk Lorikeet. But I heard plenty of them. As to koalas, not even a grunt.

Tuesday, 3 April 2018

Bowkeria and its sticky shell flower no good for oil-prospecting bees


The Natal Shell-flower Bush grows naturally in the scrub beside creeks in eastern South Africa and Lesotho (the latter a country I have visited, briefly, from South Africa). In Melbourne Gardens it grows in what we call the Southern Africa Collection, beside the pedestrian entrance to Gardens House.


As PlantZAfrica puts it, Bowkeria verticillata is a 'decorative shrub ... with soft quilted leaves and pure white, scented flowers'. But the flowers are not only white and scented, they are also a little icky to touch. According to PlantZAfrica they are 'sticky and glint in the sunshine'. Which they are, and they do.

Natal Shell-flower Bush is one of only three species of Bowkeria, all native to the same part of Africa. Siblings Henry and Elizabeth Bowker were local naturalists of renown in 1859, when the genus was named.


In Melbourne Gardens, Bowkeria verticillata is a messy shrub about 4 metres tall. The flowers, in January, are easily missed. Walking by I noticed what looked like small blobs like bubble gum among the viburnum-like leaves.


On closer inspection the flowers looked like a closed mollusc of some kind. And then I noticed the plant label with its helpful common name, Natal Shell-flower Bush. So these oyster-shaped flowers I was looking at were not abnormal and the plant came from South Africa.


The family on the label was Scrophulariaceae but there have been lots of changes recently in this branch of the Tree of Life, with what used to be a large family now split and redistributed. These days we include Bowkeria in the oddly named family Stilbaceae with 11 other genera, including Stilbe.

Contrary to reports, when I rip open a flower it does not exhibit a 'pattern of red marks' on the inside of the scalloped petals, apparently there to guide oil-collecting bees to 'oil hairs' at the centre of the flower. These bees (again according to PlantZAfrica) move the oil from the their front to hind legs and carry it there to feed larvae in the nest.

Along the way I take it they accumulate a little pollen as well, which they distribute between flowers. There doesn't seem to be any pollination advantage to the sticky flowers although I image the surface deters a few unwanted visitors.


In our flowers you can see the four anthers, neatly tucked into the pocket at the base of the flower, and the tubular female receptor (style) in the middle. But no guiding colour bands on the bit pealed away (on some flowers there are faint hints of colour...), and no oil hairs anywhere that I can see. Perhaps they are very small.

The fruit, if it sets without oil hairs and oil-collecting bees, is a 1.5 centimetre long capsule said to look like 'polished cardboard', and remaining on the plant long after it splits to release the tiny seeds. In early February, at the tail end of the flowering, I could find only these woody (cardboardy?) remains of flowers, still quite sticky.


A few of the ovaries looked like they were fertilised, so I tracked the plant through March hoping to find some mature fruit. Sadly, as we arrive at April, nothing to post about.

Tuesday, 27 March 2018

Bum-shaped leaves but rose-scented wood


What's rosewood when it's at home? By home I mean not French-polished in a sideboard but in, for example, Argentina, Bolivia, Brazil or Uruguay. That's where Tipuana tipu, just one of the world's rosewoods, lives and breathes.

And what a melodious botanical name. I gather both the genus and species name come from the local Peruvian name for the tree, tipa. A tipu is also a small bird or chicken.

So what is this tree, whether in its home in South America or planted in Melbourne Gardens (as photographed here in late December 2017)? Well it's a pea. Or if you like, a pea plant, or pea tree.


Look at these flowers and apart from a little frilliness they look like any other pea or bean flower. Also the leaves made up of small 'leaflets', typical of the rather large (with some 19,000 species) family Fabaceae.

There is only one species of Tipuana, commonly planted as a street tree in the tropics but doing very nicely in our temperate botanic garden here in Melbourne, Australia. It does even more nicely further north, where it has become an invasive weed in northern New South Wales and Queensland.


As noted in a fact sheet about its potential weediness, the tip of each leaflet the leaves in 'buttock-shaped'. In more polite circles we might describe this as emarginate (with a notch). Elsewhere, shaped like a bum.

There are quite a few trees and timbers with the common name Rosewood, most or all belonging to the pea family. The Convention of International Trade of Endangered Species of Flora and Fauna - better known as CITES - restricts trade in (rose)wood from all 300 species of the genus Dalbergia as well as what is called African Rosewood, Pterocarpus erinaceus. Unlisted is the New Guinea Rosewood, Pterocarpus indicus, found naturally from northern Australia through to Asia.

Then there are so-called Scentless Rosewoods, species of Synoum, in a different plant family, Meliaceae. That family is also where you'll find Dysoxylum fraserianum, the (Australian) Rosewood or Australian Rose Mahogany.  In fact Rosewood is a term used for a wide variety of tropical species, all of which share 'a dark red hue and high quality timber'.


Our Melbourne Gardens' Rosewood has one extra feature, a winged fruit. This is very unusual in the pea family and looks more like what you'd expect on a maple (Acer), although split in half.

So our rosewood, also called Pride of Bolivia, is variously masquerading as a Dalbergia, an Acer and, if you must, lots of tiny bums.


The images were taken in the Melbourne Gardens, late December and early January 2017, and the red flowered 'subshrub' in the last pictures is of course a Brachychiton

Tuesday, 20 March 2018

Chain of hearts attracts (aptly) blood-sucking midge


There are more than 200 species of Ceropegia, one of them much loved as an indoor and sometime outdoor plant called Chain of Hearts, or some other variation on the theme of hearts, unavoidable given the shape of the leaves. The word rosary gets into some common names, playing off the chain metaphor.


Ceropegia is in the nowadays very large family Apocynaceae, with lots of other milky-sapped genera, such as oleander and frangipani. It sits though with the vast majority of the genera, and more than half of the 5000 or so species, in a subfamily called Asclepiadoideae, along with the closely related fellow succulent Stapelia, with its soft, unpleasant-smelling flowers.

Most species of Ceropegia grow naturally in Africa but they extend through into Asia. My illustrated species is Ceropegia woodii (sometimes called Ceropegia linearis subspecies woodii), from southern Africa and my specimen is a pink-tinged, variegated cultivar. Although some side shoots produced almost entirely pure white leaves.


The flowers are like hemorrhoiding vases. They capture insects, temporarily. While the insect is rummaging around inside the floral tube it gathers or delivers pollen. About 60% of species have an exclusive relationship a single genus of pollinator, the rest we would describe as generalists. A blood-sucking midge favours this small-flowered Ceropedia woodii.

Most visiting midges are female, and it's thought the flower is mistaken as a suitable egg-laying place. Typically the larvae of midges such as those that pollinate Ceropedia woodii feed on rotting plants and fungi. The pollen is almost always attached to the mouths of the midge.


Apart from looking like a rotting flower or fungus, I guess, the flowers have a perfume attractive to broody midges. Sometimes we can smell it. In the single flower I found, there was no attractive or unattractive perfume that I could detect.

In fact the role of the colours and various attachments on Ceropedia flowers are still not fully understood. They may add to the appeal of the flower once the midge has been guided into the general vicinity by the perfume.


This particular species of Ceropegia, but not all of them, produces potato-like tubers at the leaf junctions (below) and these can be used to propagate a new plant. The easiest way is to layer the intact stem onto moist soil, before you separate it from the mother plant.
  

More chains of hearts. More funny-looking flowers. More confused midges.

Thanks to Kate Cregan for her gift of the plant photographed, as a moving-in present a few years back.

Tuesday, 13 March 2018

The Top 10 ‘first’ botanic gardens (Plant Portrait XVIII*)



WARNING! LONG READ...


Roger Spencer and Rob Cross, in a recent article in the scientific journal Muelleria, document the origins of botanic gardens (and more). They confirm that the ‘oldest existing [my emphasis] botanic gardens date back to the early modern period, to the educational physic gardens associated with the medical faculties of universities in 16th-century Renaissance Italy’. This is generally accepted, although there is some debate – alluded to in Spencer and Cross’s article – around the ‘first botanic garden’. Some of this is a minor quibble about continuity: the first botanic garden built in Italy was in Pisa, in 1544, but in 1591 the entire garden was moved a few blocks away from the river, making the botanic garden of Padua (apparently early in 1545; closely followed by Florence in December 1545) the oldest botanic gardens continuing in the same location.

More interesting but ultimately unresolvable (except through precision of definition) is whether there were botanic gardens, or things like them, in antiquity. The closest match, as Spencer and Cross document, is the 4th-century BCE garden at the Lyceum in Athens. It certainly contained a collection of plants used at least in part for scientific observation. To my knowledge the plants were not labelled in any way, a characteristic inevitably included as any definition of a botanic garden, and the landscape and horticulture were probably not particularly ‘ornamental’. Spence and Cross quite rightly argue that contemporary botanic gardens generally include ornamental horticulture as part of their ‘mix of science and education, art and utility’. There are further nuances in this debate. The botanic garden in Leiden (1587) may have been the first garden with ornamental and scientific values, and not just growing plants for their medicinal use. And if medicinal gardens are allowed into the club, there were some established outside of Europe in the 16th-century, such as the one established by the Portuguese in Goa (now India).


In the next century, the University of Oxford Botanic Gardens (1621) and the Chelsea Physic Garden (1673) were established, well before Royal Botanic Gardens Kew in London (1759). Somewhere in between, in 1718, Jardin de Plantes in Paris changed its emphasis, and name, from medicinal plants to plants more generally. In the US, The Missouri Botanical Garden in St Louis, established in 1859, describes itself as ‘the nation’s oldest botanical garden in continuous operation’. So too does the U.S. Botanic Garden, in Washington DC, which opened in 1850: ‘the oldest continuously operated botanical garden’. And I‘ve seen Bartam’s Garden in Philadelphia, which started in 1728, called ‘the oldest surviving botanic garden in North America’.

What about in the Southern Hemisphere? I’ve often said, for reasons I can longer remember, that the Jardim Bot├ónico do Rio de Janeiro in Brazil, established in 1808, is the oldest south of the equator, followed by Sydney in Australia (1816) and Bogor in Indonesia (1817). I may have been a little parochial, having visited all three and being Director of the middle one for a while. In any case, Spencer and Cross designate the Sir Seewoosagur Ramgoolam Botanical Garden in Mauritius, established in 1736, or more formally as a botanic garden in 1767. Then there is the Company Garden in Cape Town, begun in 1652 and already, according to Spencer and Cross, ‘an exceptional botanic garden’ by 1680. I visited the Company Garden in 2005, and while now outside the botanic garden network in South Africa, it could still be technically considered a botanic garden.


It’s a complicated business tracking down when a garden begins and even harder, perhaps, to determine when it begins to be a botanic garden. All botanic gardens will be a little less ‘botanic’ in their early years even if established as such right from the start. The mobility of some makes it even more difficult to nail down when and where they start to function as a botanic garden. Then there is the fundamental question of what makes a garden botanic. There are have many attempts, with these four (including one of my own) representing a progression over the last 50 or so years:

1.        ‘...open to the public and in which the plants are labelled’ (International Association of Botanic Gardens 1963)
2.       ‘A garden with (noting that this list does not constitute a comprehensive summary of the activities undertaken by botanic gardens):
          adequate labelling of the plants
          an underlying scientific basis for the collections
          communication of information to other gardens, institutions, organisations and the public
          exchange of seeds or other materials with other botanic gardens, arboreta or research stations (within the guidelines of international conventions and national laws and customs regulations)
          long term commitment to, and responsibility for, the maintenance of plant collections
          maintenance of research programmes in plant taxonomy in associated herbaria
          monitoring of the plants in the collection
          open to the public
          promoting conservation through extension and environmental education activities
          proper documentation of the collections, including wild origin
          undertaking scientific or technical research on plants in the collections’
(IUCN-Botanic Gardens Conservation Strategy 1989)
3.       ‘…institutions holding documented collections of living plants for the purposes of scientific research, conservation, display and education.’ (International Agenda for Botanic Gardens in Conservation 2000)
And most recently, a definition I proposed at the 6th Global Botanic Gardens Congress in Geneva in 2017 for what I called 4th generation botanic gardens (the standard we should be seeking in the modern era):

4.       ‘…a scientifically managed and inspiring landscape of documented plant collections, where every plant and setting has a purpose’ (Entwisle 2017)

So do any of these definitions help to create our chronological listicle? The commonality of them all is the need for documented, or slightly more limited labelled, collections. Apart from the first definition, the plants planted have some purpose. Being open (and welcoming?) to the public is important implied rather than explicit in the latter two definitions but a given. The role of ornamental horticulture comes through in the last two as display in number 3, and in number 4 a reference to inspiring landscape plus the addition of the word setting as well as plants when it comes to purpose.

While I like my aspirational definition for a modern botanic garden (number 4) I don’t see it an exclusive one. More helpfully for our listicle I would suggest:
  • A documented collection of plants to some purpose
  • An ornamental and purposeful landscape
  • Open and welcoming to the ‘public’
  • A scientific (or if you prefer, evidence-based) approach to their management and use
These points will not please everyone (and I’m sure they could be improved) but using them, albeit subjectively, one can create a list of firsts, or nearly firsts. Being first says nothing, of course, about the quality of the botanic garden, then or now. I’ve decided to adopt the need for the botanic garden to stay in the same place, more or less (that is, with at least some common ground throughout its history). Otherwise we need to examine the current scope and concept of the organisation running a garden, and in some cases trace back cobwebby threads to botanic-like garden in history. As to botanic gardens that existed once but not now, they are simply too hard to document and review (although such a list I would admit has equal validity as mine). The nomenclature for the organisation, the city and the country are as used today, with the geographic location in English. Those in italics I don’t think meet all the criteria above but have some claim to being botanical-like gardens.

So, here then is my list of the Top 10 first botanic gardens, with apologies to all the countries and regions left out.

First on Earth
1545       Orto Botanico di Padova; Padua, Italy
1545       Orto Botanico di Firenze (Giardino dei Semplici); Florence, Italy
First on Earth with strong scientific and ornamental values
1587       Hortus Botanicus; Leiden, The Netherlands
First in the United Kingdom
1621       University of Oxford Botanic Garden; Oxford, UK
First in the Southern Hemisphere
1652       The Company Garden; Cape Town, South Africa
1736       Sir Seewoosagur Ramgoolam Botanical Garden; Pamplemousses Mauritius
First in the Americas
1850       U.S. Botanic Garden; Washington, USA
1859       Missouri Botanical Garden; St Louis, USA
First in China
1860       Hong Kong Zoological and Botanical Park; Hong Kong, China
1929       Nanjing Botanical Garden Memorial Sun Yat-sen; Nanjing, China

Oh, and the Royal Botanic Garden Sydney was began life in 1816, making it the first in Australia. We don’t talk about this much at the Royal Botanic Gardens Victoria (1846).


Images: Padua, Oxford, Florence, Leiden (a little faded, from a 1997 slide) and Melbourne.

Postscript: There is plenty here to debate and question, and I'm sure many 'firsts' I've missed. I'll list here feedback that comes in on that score...
Peter Teese (via Facebook, 13 March 2018): Penang Botanical Garden about 133 years old & Perdana 1880s in K L might be of some interest. 1876 Sri Lanka Gampaha Botanical Garden, first rubber from South America.
Ann Harding (via comment on this Blog, 14 march 2018):Saint Vincene, West Indies, has a very old botanic garden but I don't see any mention. Very nice collection including spice trees.
*Occasional posts are called Plant Portraits (in brackets after the blog title and marked with an asterisk). These are usually about things other than, but including at least passing reference to, plants. Often they will be inspired by a book or something else in my cultural life. The idea is borrowed (very loosely and with due deference) from Milan Kundera's 'Novels, Existential Soundings', in his Encounters. These essays were as much, or more, about things other than the book being reviewed. In my case, it could be that every story has a plant to tell... 


Tuesday, 6 March 2018

Dasylirion again, with fibre and indent


The last time I posted on a Dasylirion - an agave relative with a no-frills columnar flowering stalk - I placed it in the family Dracaenaceae, the Dragon Tree family. Before that it used to be nestled in with agaves in the Agavaceae. Nowadays, it is with asparagus, in the Asparagaceae, albeit in its own little subfamily Nolinoideae along with the Dragon Tree, but also aspidistras and mondo grass!

Today's examples are from the Melbourne Gardens, and likely to be Dasylirion wheeleri and Dasylirion acrotrichum. Our Identifications Botanist, Val Stajsic, says this genus (and related Beaucarnea) are tricky to identify and all five named species in our collection need checking.

For this post I'm assuming the ones with leaves twisted about half way up and with a necrotic but mostly undivided tip are Dasylirion wheeleri, from Texas up to Nevada and North Carolina. One of them on Guilfoyle's Volcano sports a nice label supporting this identification. The other, below, has less of the twist but more going on at the tip of the leaf - a wonderfully eccentric fraying. These fibres, and those embedded within the rest of the leaf, are used by native American to weave baskets and mats. It's (I believe) Dasylirion acrotrichum.


But let's return to Dasylirion wheelerioften called Common Sotol, from west Texas, New Mexico and Arizona. You also see the name Desert Spoon, but that is applied to various species of Dasylirion, including the Texan Sotol, Dasylirion texanum, I featured last time.

Sotol is the name of an alcoholic drink, similar to Tequila and Mezcal but made from Dasylirion growing in the vicinity of Chihuahua. (The spirits distilled from succulents in Mexico have a nomenclature as complex as the genus Dasylirion, based on the species used, its origins and then aspects of the production process.)

Unlike their agave relatives, the Desert Spoons don't die after flowering but then they won't necessarily bloom every year either. The inflorescences are packed full of flowers, either male or female, but usually not both on the same plant (but see below). This is Dasylirion wheeleri with a (broken) male plant on the left and a(n unbroken) female plant on the right.


Katherine Darrow, in her blog on a desert park in Phoenix, says you can easily pick the male plants by their 'long curly bunches of pollen-producing flowers'. She says they look like Cheetos 'but without the orange dye'. I was thinking maybe Twisties but you know the kind of thing.


Although ... in our specimens of Dasylirion acrotrichum (with the frayed leaf tips), like others in the genus I gather also meant to be either male or female, the ostensibly male flowering stems do include a few male+female flowers. As this next picture shows.


Darrow also makes the interesting observation that you'll find bees and other insects swarming around the male flowers harvesting pollen, but none around the female flowers. Sure enough, plenty of bees and crawly ants on the male flower stems. Here's a bee, half way up, but the ants are too small to see. (Below that a flowering stem on its side so you can see more bees...)



But none on the females.


That's because neither sex produces nectar, the other thing bees are after. So the bees (and ants) presumably have no, or little, pollination role. Instead these plants rely on wind for pollination - hence the large amount of pollen produced and the tall, wavering flowering stalk.

Both species have imprints in their leaves from the spiky edges of their neighbours and the picture below of Dasylirion acrotrichum shows them clearly. This is an attractive feature of many agave relatives, and something I mentioned a few weeks ago.  It's also a reminder that these are spiky plants and you should take care when planting any species at the edge of a garden bed.


Tuesday, 27 February 2018

It's a girl, he says stereotyping a febrifugeous hydrangea


We had been waiting patiently for the flowers of the Blue Lacecap to help balance out the preponderance of pink and pale flowers in our back garden. Through December the buds stayed closed and mostly white, albeit with just a tinge of colour. Then, in the first week of January, the unfurling.

To reveal ... pinkish-purple flowers...


What I hadn't realised, and what isn't expressed in the usually reliable descriptions from Missouri Botanical Garden or the Flora of China, is that the flowers of this Dichroa species aren't always blue (or white). Like the related and commonly grown Hydrangea macrophylla, the flower colour depends on the amount of aluminium available in the soil (often using acidity as surrogate measure - acid for blue, akaline for pink).

The genus name, meaning 'twice colour', may be a hint; or it may refer to something entirely different! Jane Edmanson, to her credit, describes the colour alternatives in her brief write up of this species for Gardening Australia in 2015, and nurseries such as Brenlissa are on to it, using an ambivalent common name, the Blue/Pink Cap.

Which also raises the matter of the common name I was given (when the plants were purchased). Lace Cap or Lacecap is a grouping term usually applied to those hydrangeas with smaller fertile flowers surrounded by a ring of showy sterile flowers. In the case of Dichroa, all flowers in the cluster are fertile. Such are the vagaries of horticultural taxonomy it may be that Blue Lace Cap or Blue Cap is a selected cultivar rather than a general common name, explaining perhaps why my blooms at home are more showy than those (from a true species) in the botanic garden.

In any case, I think our backyard blooms are best described as lilac in colour, that is, pale violet, purple or even mauve. Photographs don't quite capture what I saw in sunlight. In any case, more at the pink end of the spectrum than the blue. Which means we have presumably alkaline soils with less available aluminium.


In the Melbourne Gardens, however, we have a plant growing in a heavily shaded part of the South China Collection, and its flowers are, and you can see (a little past their peak), pale blue. Plenty of acid in the soil here, providing aluminium for those all important blue colour chemicals.


Although not mentioned, even as 'rarely cultivated', in Roger Spencer's Horticultural Flora of South-eastern Australia, the Blue Lacecap (Dichroa febrifuga) is destined to sit alongside the Oak-leaf Hydrangea (Hydrangea quercifolia) as one of the harder, less water-guzzling 'hydrageas' for the home garden (albeit not quite as dry tolerant as that one). That's not to say it doesn't like a drink or doesn't droop a little at the end of a summer's day, but it seems to be a little more dry tolerant than the deciduous Hydrangea species.

There are 12 species of Dichroa, all from the Asian region. Jane Edmanson says Dichroa febrifuga, the name generally applied to the plants photographed here, comes from the Himalaya region of Nepal, which it does, but also from India, China and through to Papua New Guinea. It grows at altitudes from 200 to 2000 metres above sea level.

In China, the Blue (or pink) Lacecap is a widely used medicinal plant, particularly to control fevers - the species name is a Latin compound of febris (fever) and fugare (expel). As Missouri Botanical Garden remind us, the English word febrifuge is used for things that reduce fever. Dichroa febrifuga is sometimes even called Chinese Quinine, from its use in treating fever associated with malaria.


A pretty and interesting plant, whether flowering blue, pink or lilac. I was waiting with some anticipation for the berries to appear which, although sometimes hidden among the foliage, were said to be very 'ornamental', and, apparently, gentian blue... What I can report instead is that our cultivar, our climate and/or our garden are not conducive to fruit formation. All we have in late-February are brown and drooping flower heads.