Tuesday, 13 March 2018

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


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 Botânico 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.

Tuesday, 20 February 2018

A common topic, vulgarity in the garden

Our Curator of Horticulture at Melbourne Gardens, Peter Symes, considers Disoma (Coleonema pulchrum) to be one of the most boring and common plants in gardens. I'm included to agree with him, adding Viburnum, various kinds of box hedge and Mondo Grass... But then I think, I've got some Mondo Grass in my backyard and I quite like it!

As they say, familiarity breeds contempt, unless it's in your own back (or front) yard. Conversely, I've come to love plants I once thought common, such as geraniums, Oleander and hydrangeas. Of course I'm deliberately confounding plants that are encountered frequently (common) with those that I consider a little vulgar (common).

Vulgarity is more interesting. On the weekend you may have heard me scour the Melbourne Gardens in search of vulgarity for ABC RN's Blueprint for Living. I interpreted the term broadly, starting with the vulgarity of plants in general, allowing their reproductive bits to flap around in the wind only scantily wrapped in petals. You could describe a garden - or a garden show in spring (as at top of post) - as a gathering of vulgar creatures with their sex organs (flowers) hanging out. And we humans admire and dissect those organs.

Then there are the plants that are vulgar in a common sense. In fact we name some 'vulgaris' or 'vulgare' because they are all over the place, at least when and where described. There are plenty of these in our Herb Garden, e.g. Origanum vulgare. (This garden also includes a lot of plants called 'officinalis', after their beneficial use to humans, often medicinal.)

A few of the vulgarly named plants you might encounter outside the herb garden are Echium vulgaris (Patterson’s Curse) in farm paddocks, Acetosella vulgaris (Common Sheep Sorrell) on roadsides and in farmland, and Cirsium vulgare (Spear Thistle), a vulgar and noxious weed (although I quite like thistles...).

You might also think some flowers are vulgar due to their overly exuberant displays. Perhaps the big and blowsy begonias or tulips? Or those with cheap perfumes, such as some daffodils, jasmine and lilies?

At the other end of the vulgarity spectrum are plants that are offensive or confronting to our senses (which I suppose some of the cheap perfumes are as well). There is a whole gaggle of plants with blooms or fruits exuding bad smells. Think duran fruit and its vomit-like odor, through to the various corpse flowers smelling like dead animals to attract pollinating flies - e.g. species of Rafflesia and Amorphophallus.

Look beyond the green plant world, to the fungal kingdom, and there many more vulgar attractions, such as the aptly named Phallus or the stinkhorns (Aseroe). There is a lovely story (thanks for reminder Teresa Label!) about Beatrix Potter’s aunt walking ahead of a group of young girls (including Beatrix, not only a writer and illustrator but a scientist with an interest in fungi) covering with a lace cloth any vulgar-looking fungi.

Then there are orchids, and a few other plants, that rely on (pseudo)copulation by male wasps and other insects for their pollination. Unrequited sex, in the garden and in our forests. How vulgar.

To finish, and if you want juvenile vulgarity, you can snigger as you try to pronounce Silybum marianum (a thistle) and Dendrobium biggibum (an orchid). There are also common and scientific names I’m much too polite to mention here, such as one of the names for Dionaea muscipula, politely known as the Venus Fly Trap. I'll leave that with you.

Images: The RHS Orchid and Art Show in London (2012), a trio of botanists (Peter Weston, Barbara Briggs and Adam Marchant) gathered around the sexual apparatus of a Lotus flower, the giant Titan Arum in flower in Royal Botanic Garden Sydney (with its keeper, Stephen Barlett), an illustration of a fungus by Beatrix Potter, a frustrated wasp on a Chiloglottis (photographed by Ray and Elma Kerarney, via Peter Weston, a few years back), and a clump of Venus Fly Traps.

Tuesday, 13 February 2018

Chestnut a surprising product of aquatic sedge

While on the subject of pseudo-cereals (but not superfoods), as I was last week, what about Water Chestnut? You will have guessed already that it's not a true chestnut (a species of Castanea), or even a horse chestnut (Aesculus hippocastanum), but something that might just grow in water.

In fact there are two edible plant products sold under this name. 'Chinese' Water Chestnut (above) is the corm ('bulb') of a sedge called Eleocharis dulcis, while what is sometimes also known as Water Caltrop (below) is the seed of a Lythrium (Loosestrife) relative called Trapa natans. Both grow in wet places.

The Water Caltrop is considered by Bohuslav Brouk, in his Plants Consumed by Man, to be a pseudo-cereal. According to Brouk, although the seed has been used since Neolithic times, today the fruits holding the seeds have more currency, as 'curios and souvenirs'. (I should add that this 1975 book was savaged at the time in many reviews, including this summary in the journal Economic Botany: '...[a] non-book, such a pretty package of misinformation, such inadequate coverage under such a grand title and pretentious jacket "blurb"...)

In Australia I've only seen the Chinese Water Chestnut for sale. In China the corm of Eleocharis dulcis is used in many dishes, often raw, although it has the attraction of remaining crunchy even when cooked. Yet despite its common name, Eleocharis dulcis grows naturally in many countries, including Australia. It has a tropical to subtropical distribution through much of Asia, across to Madagascar.

As Kathy Stewart and Bob Percival record in Bush Foods of New South Wales, the Chinese Water Chestnut is used by Aboriginal people in Australia, with old corms roasted and younger ones eaten raw. The stems are also used, to help in heal and seal open wounds. Magpie geese, also part of the diet of Northern Australian Aboriginal communities, graze heavily on this plant.

For more information on the Chinese Water Chestnut I eschewed Bohuslav Brouk in favour of Circular No. 956 put out by the USA Department of Agriculture in 1955... There I learn that the sedge is grown like 'paddy rice' in the south and east of China, where it is (or was) mostly called Matai, meaning 'horse's hoof'. The common name in English, Water Chestnut, is presumably a reference to the similarity of the corms to tree chestnuts.

To the USA palette, in the 1950s, the prepared Chinese Water Chestnut had a 'crisp, white, applelike flesh ... both sweet and starchy'. Uncooked it tasted to some like fresh coconut. Cooked it became a textural addition to omelets, macaroni and cheese, stews and the like. Small corms could be pickled, or fed to chooks.

And then there are the medicinal claims. For these I had to search beyond the USA Agricultural circular. There are claims that Chinese Water Chestnut has health benefits such as 'antimicrobial effects on bacteria, antioxidant activity, inhibition of inflammation and treatment for pharyngitis and laryngitis'. Indeed a recent study found that extracts from the peels of Chinese Water Chestnut, usually discarded during preparation, could be 'potentially used as a ... food supplement [for the] ... control or elimination of food borne pathogenic bacteria'.

Not bad for a plant of rather simple structure, essentially a collection of long green tubes. There are some 200 species of Eleocharis, with quite a few yet to be documented from South America (where most known species occur naturally). I can't think of any other Eleocharis species cultivated or appreciated in a similar way to Elecharis dulcis, although other sedges are of course used for thatching, basket-making and paper (e.g. Cyperus papyrus).

Images: habit shot of Eleocharis dulcis by Christian Fischer (CC BY-SA 3.0) and hosted by Wikipedia; images of corm by me; image of Water Caltrop fruit from Speciality Produce website.

Tuesday, 6 February 2018

Chias! It's a salvia

Who would have thought? Chia comes from Salvia columbariae, Salvia hispanica or Salvia polystachya, better known as sages and belonging to the mint family (Lamiaceae). Although unlike our amenity or culinary sages, these species are annuals.

Let's call them Chia Sage, as many do. Native to western North America, Chia Sage has been long harvested as a source of 'pseudo-cereal'. While Mediterraneans plucked the aromatic leaves from their sage, the Aztecs and Mayans gathered its seed.

Hernán Cortés - 'the killer' as portrayed by Neil Young - sent chia back to Spain but its use in the Americas was severely curtailed after the arrival of the Spanish. According to one source, Agua de chia (chia water) was, until the recent revival, the only remaining use of chia in the local diet.

Now of course the whole world is mad for chia. At least for now. It joins quinoa, kale and blueberries as so-called superfads - sorry, superfoods. To support its status I can report it is packed full of omega fatty acids, soluble dietary fibre and various proteins and minerals. All of which are probably good for you but as yet with no conclusive scientific support.

For me the most exciting thing about chia is the gel formed when you soak the seeds in water. Soluble fibres in the seed coat combine with the water to produce a goo of sago-like texture. That goo (along with the rest of suspended seed) contains plenty of fat and dietary fibre.

So yet another fascinating side story about Salvia to join the Brown Salvia, the Andean Silver-leaf Sage and Meadow Clary in the Talking Plants pantheon, only one of which is illustrated among the salvias below.

And while I'm here, I've been advised on the best authority (a friend of a friend) that the next superfood from the mint family will be the Shiso or Beefsteak Plant, Perilla frustecens. I remember seeing, and photographing, this plant a few years ago in the Milson Community Garden, Kirribilli, where I interviewed Yumi Sakauchi for Talking Plants on RN.

Just in case you are wondering, Quinoa is a chenopod (in the salt-bush family) from South America, an entirely different and unrelated pseudo-cereal, and, sigh, superfood.

PS: Paul Ward, via Facebook (6 February 2018) adds: Basil seeds are popularly used in SE Asia for drinks in a similar way that chia is used. Soaked basil seeds form a mucilage around their seeds. The mucilage formed on the seeds of clary sage ( S. sclaria) has been used in Europe for removing foreign objects from the eyes. A seed is put into ones eye, and the mucilage attaches to the grit or whatever is caught in the eye. And is then easily removed.

Images: At the top is a picture of Salvia columbariae taken by Gary A. Monroe, hosted by the USDA-NRCS PLANTS Database. The other images are from my own photograph collection: the Shiso from Milson Community Garden; a close up of Salvia canariensis from Gran Canaria (Spain); Salvia pratensis in the seed orchard at Wakehurst Place (Royal Botanic Gardens Kew, UK); and the salvia border at Kew Gardens (Royal Botanic Gardens Kew, UK).

Tuesday, 30 January 2018

Floral clocks and flowering thyme

While preparing for last weekend's chat about 'time' on ABC RN's Blueprint for Living, I got diverted on Carl Linnaeus's horologium florae, his floral clock. An eccentric and impossible folly, but what fun!

Here in Melbourne we are proud of our floral clock, a nineteenth-century sensation reaching Australia in the 1960s. It consists of a buried clock, Swiss made, with giant hands sweeping across a carefully manicured garden bed. At times long-lived box hedges have added structure, but mostly annuals such as begonias and marigolds contribute bling to the timepiece. Beautiful – at least to some eyes – and reasonably functional.

The original concept of a Floral Clock was quite different, and even barmier. By the mid eighteenth century we were starting to get a grip on the variety and apparent vagaries of plant reproduction. Different plants not only flower at different times of the year, but at different times of the day. Some species are quite specific as to when they open and shut their flowers, to take advantage for example of obligate morning or evening pollinators. This led Swedish biologist Carl Linnaeus*, creator of what we call our binomial system of naming (e.g. Homo sapiens, for us, humans), to postulate a horologium florae.

With judicious planting, one can imagine a garden where the open flowers tell you the time day. In the Swedish city of Uppsala, where this idea first took root**, you might bounce out of bed when the Dandelion (Taraxacum officinale) flower-head unfurls at 6 am, rush to work when it shuts between 8 and 10 am, grab a sandwich at noon when the Field Marigold (Calendula arvensis) flower-heads close, leave work at 6 pm when the Sad Geranium (Pelargonium triste) finally opens its dull yellow flowers and, if you like, party until the Queen of the Night cactus (Selenicereus grandiflorus) blooms at midnight.

Let’s get something clear up front though. This is like picking your dream sports team of all time or forming the world’s best super band. It’s a paper or mental exercise. A true Floral Clock can’t be created in the real world. These plants won’t grow together in the same place, they won’t all flower on the same day of the year (each flower of the Queen of the Night cactus, for example, opens for one night only), you would have to re-calibrate for every degree of latitude or altitude, and depending on the weather some might not open at all.

While a full functioning Floral Clock is a folly, you could conceivably create a coarse local variant that might work in spring or thereabouts. You could start with two Victorian species of flax lily (Dianella), one of which (Dianella amoena) opens early to mid-morning, the other (Dianella tarda) early to mid-afternoon. But then you know when it’s mid-morning or mid-afternoon don’t you? Perhaps it is better to spend your time wondering how it is that plants spend their own.

Now, plants set their own clocks from the amount and quality of the daylight they receive. They have a system for tracking seasonal changes in day length, triggering when they flower or renew growth. The variations within a single day are controlled by light, temperature and even humidity, plus an inbuilt circadian rhythm like animals. Such precision is the result of evolution, with successful plants protecting their assets (flowers) until a suitable pollinator is active. For the night-flowering cactus it’s a moth. For the two flax lilies, it may be the same or different species of native bees.

Some plants will open and close their flowers on a daily cycle, by growing new cells every day in the inside (to open) or outside (to close), or by expanding and contracting existing cells in the petals. It’s worth the effort to protect delicate parts from wind, rain and dew, and to keep pollen dry and ready for action. Plants growing in tough environments are more likely to have these diurnal cycles. A good example is Pigface (Carpobrotus glaucescens), a succulent adapted to dry sand dunes, which has daisy-like flowers that close up every night. The Sensitive Plant (Mimosa pudica) folds up its leaves each night to protect that equally important, and in this case sensitive, part of the plant.

The flowering head of a Sunflower (Helianthus annuus) takes it all a step further, arcing during the day in response to its own internal clock. Young sunflower plants (with their flower-heads unopened) track the sun from it rising in the east to its setting in the west, then get themselves sorted overnight so they can do the same the next day. Once the giant yellow flower-head opens, it stops moving about and faces east.

The sunflower has a circadian mechanism behind its solar tracking, and then some internal signalling to position its mature flower-heads eastward. The solar tracking is caused by different growth rates on the sunny and shady side of the stem. During the day the cells on the east side grow a little faster than those on the west, and then vice versa at night. This all stops when the elongation of the stem stops and the best orientation for an open flower is facing the morning sun - warm flowers attract more bees.

Plants do keep time in other ways. Flowers can last a few hours (our night-flowering cactus) or a few months (moth orchids), and the entire life cycle can be a matter of a few months (desert annuals) to thousands of years (the Bristlecone Pine, Pinus longaeva). Annuals typically flower once and die, all within 12 months, but other plants, such as the Century Plant (Agave americana) and several palms, will live for a few decades then flower once and die. For most woody plants and trees, though, they flower each year and continue growing until like us they senesce.

There are plenty of seasonal cycles of course, allowing plants to survive and thrive in their particular nook and cranny of the world. We can manipulate these cycles, as we do with the Christmas Poinsettia. In mid-winter in Australia, a garden Poinsettia produces red or pink leaf-like bracts around its tiny flowers. The amount of colour change in these bracts depends on their exposure to sunlight, or rather lack of exposure. They need long 'dark periods' for about three months before they flower. Northern Hemisphere gardeners report that interrupting the ‘long night’ by even flashing with a torch during October through to December may stop the leaves changing colour.

To get our Poinsettias flowering, and ‘bracting’, in nurseries around Christmas we manipulate their environment. Glasshouses are set up to provide artificially long nights and the Poinsettia thinks its winter. Although a plant growing in my office building (hello Frank Udovicic!) persists in flowering close to Christmas without any overt manipulation, perhaps due to day length variations on its windowsill. Plant life is seldom simple and it seems you can’t really set your watch, or your Christmas shopping schedule, from a flower.

*Carl’s father devised their surname, Linnaeus, so he could register at university (before then he, like many others of the time, had no need of a surname). The Swedish word ‘linn’ is used for what we call the Linden or Lime Tree (Tilia) and the freshly minted name honoured an impressive specimen of Linden growing beside their family home. So it is no wonder Carl had such a passion for plants. Perhaps too much. His classification system for plants was based largely on their sexual organs, the flowers, and considered by some to be a little too explicit – loathsome harlotry according to one contemporary commentator.

**My source for the plants Linnaeus proposed for his horologium florae was a copy of The Natural History of Plants by Anton Kerner von Marilaun, published in 1896, and part of the State Botanical Collection library at Royal Botanic Gardens Victoria.

Images: Flowering Thyme, of course. In the Royal Botanic Gardens Victoria, Melbourne Gardens, a few months ago. And just above. a much reproduced image of Carl Linnaeus, this one from a sign in the Jardin Botanico Atlantico, Gijon, Spain

Tuesday, 23 January 2018

Isolated euphorb survives and thrives despite tragic plane crash

Eighty years ago, an Australian National Airways passenger plane, a DC-2, crashed here, on the slopes of Mount Dandenong, in the outskirts of Melbourne. All 18 people on board died when the pilot of the flight overshot Essendon Airport by 32 kilometres on a cloudy afternoon in late October, 1938, a year before the start of World War Two.

The inquiry following the crash led to various air safety improvements including an air traffic control system in Australia that became the model for airports around the world. A memorial was erected at the crash site in 1978.

Near to the memorial is an isolated population of an odd little plant called Beyeria lanceolata. Beyeria is an Australian endemic - all 24 species occur naturally only in Australia - and sometimes (like a few unrelated genera) called Turpentine Bush.

The genus belongs to the plant family Euphorbiaceae, notorious for its single-sex flowers with rather odd and diverse floral apparati, as well as in Africa mostly for the cactus-like Euphorbia species. In recent years a few smaller families have been hived off but Euphorbiaceae remains large (c. 230 genera and 5700 species) and florally odd.

Like other species of Beyeria, the male flowers have obscure petals and consist mostly of a cluster of anthers, in this case poking out of kicked back sepals (the layer outside the petals). The female flowers are a single ovary clasped by green sepals. The leaves are long and narrow.

Beyeria lanceolata grows mostly in East Gippsland, where is is rare but scattered widely, and drifts ever so briefly across the border into southern NSW (where, perversely, the 'type' specimen of the species was collected). West of the township of Sale, though, its only extant population is near this crash site (excluding a likely misidentification from Point Nepean).

The plant was collected from Mount Dandenong in 1949, 11 years after the crash and a few years after the end of the Second World War. At the time of that gathering, Government Botanist Jim Willis noted that this species was 're-located in the Dandenongs' and there were 'many shrubs covering about quarter of an acre'.

Late last year botanist Neville Walsh re-re-located the species in Mount Dandenong - although to be fair it had not really gone missing between 1949 and 2017- estimating its extent at 'about a house block'. Even allowing for house blocks having become generally smaller over the intervening 68 years you'd have to say, as Neville did, that this population has remained remarkably stable.

Still, Neville was there to collect seed, from fruits like this, just in case.

There are other plants with the bulk of their distribution in East Gippsland, and sometimes further northward, but with an isolated occurrence somewhere in the west or centre of Victoria. Examples in the fern and fern ally world include Psilotum nudum, the Fork Fern, in the Grampians; Lindsaea mirophylla the Lacy Wedge-fern in the Dandenongs and nearby; and Tmesipteris ovatum, the Oval Fork-fern from Wilson's Promontory up to the Dandenongs. 

In some cases the clearing of habitat will have caused the disjunction although you'd expect a few older records in between. None of these examples have any historical records connecting the present outliers to their eastern stronghold.

In the case of our Beyeria you might be thinking I introduced the plane crash as a possible vector. Perhaps a seed had become attached to the fuselage? Well I did, but it seems not. The plane was travelling from Adelaide rather than from the east, and there is a pesky August 1914 record - at the start of the World War One - from the same locality.

Images: all from VicFlora, taken by Jeff Jeanes, Neville Walsh and Andre Messina (credits on source page).

Tuesday, 16 January 2018

Streaky Box Elder a mixed up and unwanted plant

This is one confusing plant. Not just the striking - or shocking if you view variegation the way I do - albino streaks through every part of the normally green bits of the tree. But its identity and its name.

These fruits are the typical winged fruit of a maple, or Acer. But we all know maples have those lovely hand-like (palmate) leaves. Well, most of them (particularly in North America) do but this one doesn't.

The leaves are divided into 'leaflets', very like an ash tree or perhaps an elder. Sure enough, the common names include Box Elder, which references its odd leaves (and, I gather, to the wood being reminiscent of a Boxwood, Buxus), and Ash-leaved Maple, which references ... well, the ash, Fraxinus.

Acer negundo, as we botanists call it, is tough old species. We have this giant old one near the Terrace Tea Rooms in Melbourne Gardens, most of it living up the cultivar name of 'Variegatum', and the modified common name, Variegated Box Elder.

The species name, negundo, is another nod to look-alike plant, Vitex negundo. That plant also has leaves divided into leaflets, five in its case, and was named after a local Sanskrit/Bengali word for the plant, nirgudi.

The Box Elders have three to seven, or rarely nine, leaflets. A handful of varieties have been described based on the number of leaflets, how hairy they are, and the colour of the stems (some are a beautiful glaucous grey). Ours seems to match the variant found throughout most of the USA called variety negundo.

So much for its name. Those white streaks and blotches bother me in the leaves but on the early summer day when I took these pictures, I have to say I was quite taken by the veils of white fruits. That's cool. And no doubt responsible for another of this cultivar's common names, Ghost Maple.

No sooner do I find myself attracted to a variegated plant though and it shows me its flaws. This one is reverting to green foliage and fruits in various places. Which begs the obvious question: will the entire plant eventually become green-washed? 

Variegation you'll recall is mostly likely the result of a genetic mutation. It seems that in this specimen the 'defect' holds true mostly but ever now and then reverts back to normal at a growing tip - so one branch becomes green again. What you can't tell from a single observation like this is whether the tree is transitioning - if I can use that term - to no variegation, or simply expressing a similar proportion of reversion to what it's done all its life.

They say this cultivar is one of the most commonly grown in Australia and you do see planted as a street tree not far from the Melbourne Gardens. So I could soon make my own assessment as to whether there more all-green leaves on older trees or whether they are in roughly the same proportion no matter what the age of the tree.That all assumes of course there is no manipulation of the system, which it turns out there is.

In VicFlora, where the species is listed as a 'naturalised' species for the State (i.e. a weed that has become established among natural vegetation) we read that 'variegated forms soon revert to wholly green-leaved plants in the wild'. But, 'in cultivation, green-leaved sucker stems are usually removed to retain the variegated foliage of the central stem'. These statements are borrowed from the Horticultural Flora of South-eastern Australia.

The sucker stems in Melbourne Gardens are all over the tree, as they are in the street trees nearby, and it seems their days are numbered. Otherwise our Variegated Box Elder would simply be a Box Elder.

Given the rather disparaging remarks made about the potential of this species as a weed of forests and woodlands, particularly near rivers, perhaps instead of removing green shoots we should remove the whole tree. In Victoria Box Elder is already 'a problem at Wilsons Reserve in Ivanhoe and in Knox City Council'. 'In fact' says the Queensland-based Weeds of Australia site, 'some environmentalists believe it to be among the worst environmental weeds growing along waterways in Melbourne'.

This is where our carefully manicured Variegated Box Elder saves the day. According to the Horticultural Flora it produces sterile seed. Lots of it, but none perpetuating the parent. I'm assuming this refers to the variegated-leaf branches only, providing another incentive to trim the green growth. The choice seems to be between a weedy green tree and a barren but benign ghost-like mutant.