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.

Tuesday, 9 January 2018

Giant asparagus makes up for lack of mezcal

In late October, a couple of huge asparagus-like stalks erupted from Agave parryi rosettes in Melbourne Gardens. A month later (below) the stalks transformed into what look like small pine trees, flaunting brushes of golden flowers. The species is scattered through the Californian Garden (above) and atop Guilfoyle's Volcano (below, along with Echium and barrel cacti vying for attention).

The Mescal Agave, as commonly called, is one of 160 species of Agave, all of which come from North and South America, mostly from Central America and particularly from Mexico. Conveniently, given the structure of the young flowering stalk, Agave is these days considered to be a member of the Asparagaceae, a rather large family now of more than 100 genera and nearly 3000 species.

So what's with the common name Mescal. Firstly the spelling. That's the way many non-Mexicans spell the name of the distilled agave spirit, considered to be a 'kind of' Tequila. 

In fact, the legal and Mexican spelling of mezcal/mescal, the spirit distilled from Agave, is mezcal. Mezcal, according to Amy Stewart, author of the entertaining and informative The Drunken Botanist, can today only be made in five Mexican states, from species of Agave species growing in those areas. 

Tequila needs to come from somewhere near the city of Tequila and from Agave tequilana 'Weber Blue' (although most tequila drunk outside Mexico, again according to Amy Stewart, is fermented from sugars from various agave as well as other sources). There are other agave-based spirits with their own fancy names.

What I can't find is Agave parryi listed specifically as the source of any agave-based spirit: mezcal, tequila or otherwise. Native Americans used the species for 'food, fibre, soap and medicine' and although linked to pulque (an inferior kind of alchoholic beverage) and mezcal on some sites the reference seems to be more a general one and could relate to a range of agave species.

Mescal Agave comes from high altitude grasslands, scrub and woodlands in Arizona, New Mexico and northern Mexico, and according to the Missouri Botanical Gardens site it flowers 'infrequently', 'rarely' and more helpfully, after 10-15 years (although sometimes taking 20-30 years, which is far closer to rarely).

Mostly it is grown for its attractive leaves, glaucous grey with a sharp terminal point and neat imprints of the leaf from either side, a ghost memory from the time they shared a common bud.

Like most agaves, each rosette will flower once, then die. Pups or offsets at the base will then take over until they too flower and die. And so on. Here you can see a well known species, Agave americana (the Century Plant), going through its paces on a roadside in South Yarra.

We have plenty of Mescal Agave pups - and even more semi-mature canines - so expect to enjoy a procession of summer blooms over coming years. I know our rainbow lorikeets will.

Images: the asparagus-like shoot next to Neville Walsh was taken on 23 October 2017, the rest are from 28 November 2017. The species is sometimes split into varieties. Ours would be variety truncata.

Tuesday, 2 January 2018

Stealing the soul of the coral flower

We've acquired a rather planned and, so far, very neat back garden. This is somewhat of a novelty for us but an enjoyable one. Part of that orderliness are strategically placed heucheras from North America. There is a bronze-leaved one and a silver-green leaved one. The former has whitish flowers, the latter deep-pinkish. All very nice and neat.

(My wife) Lynda is keen to do a painting of its flowers, and maybe it more generally, so I was asked to take some photographs with my android-less camera. The enlarged images make it easier to see, and draw, the attachment of various floral parts and detail of important things like surface hairs.

Lynda was also trying to work out what was a petal and what was a sepal, to gain a deep understanding of the flower before she steals (or is it elevates?) its soul. First I needed to do much the same by giving it a name. The bronze-leaved forms were purchased as 'Marmalade', 'Peach Flambe', or perhaps a mix of both, but we had no name for the silver-green-leaved, deep-pink-flowered form.

I'm thinking it is one of the so-called Bressingham Hybrids, Heuchera x brizoides, crosses between Heuchera sanguinea and Heuchera micrantha. There is certainly some Heuchera sanguinea in there, such as having the male parts (the stamens) shorter than the petals, and presumably some Heuchera micrantha in the very long sprays of flowers.  

The flower is tricky to decipher but I think the two pictures above show the structure pretty well. The floral bits are mostly in groups of five. The sepals (the outer layer, sometimes called the calyx) and petals alternate along the top of a puffy pink cup, all covered in hairs tipped with glistening, deep red, spheres. The petals in the pictures above are thinner and attached behind the neat V of where the sepals join. In this next picture you can see the slightly weaker petals between the three sepals on the bottom half of the light pink flower.

In older flowers, like the couple behind the light pink one, the sepals redden up and the softer petals shrivel. You can see that clearly in this next picture, with not trace of the petals.

The common name for Heuchera is Coral Bell, or Alum Root. Coral Bell refers to the pink flowers of some species, particularly Heuchera sanguinea, and works well for what we have in our garden. Alum Root is apparently something to do with the roots being used in pickling, like alum (aluminium sulfate). The astringent properties of the roots also make it useful in folk remedies to 'shrink tissues' - blood noses, sore throats and piles are mentioned in dispatches.

All 55 or so species of Heuchera come from North America, where they grow mostly in woodlands, favouring crevices and hillsides. Like other members of the family Saxifragaceae you find them more often in cooler regions: I posted a story a few months ago about an alpine member of this family's namesake, Saxifraga.

It's now up to Lynda to represent the beauty and the structure of this tiny flower in a water colour painting, no matter what name I give the cultivar and no matter what each of those floral bits does. All that is the devil's work!

Tuesday, 26 December 2017

Floral rain and flames brighten Chinese urban forest

I'll finish the year with another story from Chongqing, in central China. While visiting in October I noticed smudges of orange and red in the plentiful urban forests around the city. Firstly from my hotel room, then from the pagoda viewing platform at Eling Park, and to be fair, pretty much from every vantage point in the city...

They are part of the remnant or regenerated forest that carpets the hillsides in Chongqing, but also planted in formal garden beds and as a street tree.

You might call them golden rain, flames or bougainvillea-like-sprays. These words combine to provide some of the names for the local Koelreuteria bipinnata with its orange-shaded, puffy, three-winged, papery fruit.

The Bougainvillea Golden Rain Tree as one common name has it, has small, yellow flowers, with a fleck or red at the base of the petals. But the flowers are produced in large clusters, presumably the golden rain. Or maybe that's the flush of yellow leaves in autumn? The Chinese Flame Tree common name hints strongly to its origins, and to the colour of the fruits. 

There are three species, two in China and Japan and one split between Taiwan and (apparently) Fiji. All seem to be tolerant of tough urban conditions, tolerating pollution and 'challenging' soils.

Koelreuteria paniculata typically has once divided leaves (or barely twice 'pinnate') and grows naturally in China, Korea and Japan. In China it occurs in Anhui, Gansu, Hebei, Henan, Liaoning, Shaanxi, Shandong, Sichuan and Yunnan, but is widely planted elsewhere, including Australia. 

Koelreuteria elegans subspecies formosana only grows naturally in Taiwan and has 'leaflets' (the ultimate leafy bits in the divided leaf) with a strongly oblique base. It is planted and weedy in northern Australia.

I'm thinking the species I saw and photographed in Chongqing is the third species, Koelreuteria bipinnata, with twice pinnate leaves (see above). It comes from natural forested slopes in Guangdong, Guangxi, Guizhou, Hubei, Hunan, Sichuan and Yunnan, as well as Japan. Until the 1990s, Chongqing was part of Sichuan so I'm presuming the species is more or less native to the area.

According to John Grimshaw and Ross Bayton's New Trees: Recent Introductions to Cultivation, Koelreuteria bipinnata was introduced into France in 1887 and California in 1911. It didn't become popular in Europe but is now widespread in warmer parts of North America. Although not considered 'hardy' in Lonon and Paris, Grimshaw and Bayton suggest that with the changing climate it is worth planting now in southern England. In Australia this species is rarely planted but there are three specimens in Melbourne Gardens, two near the Plant Craft Cottage.

In terms of which species to try, there is not much in it. All three are relatively minor variations on a theme, even with the additional flourishes such as pink new growth and pinker fruits available in cultivars of paniculata. And they should all do well in the warming, drying climate predicted for southern Australia. Possibly too well of course and I'd prefer to not see golden rain and fruity flames from every vantage point in Melbourne.

Tuesday, 19 December 2017

Another parasite for Christmas, Cistanche

This being my last post before Christmas Day it's time to talk about parasites. Not those that visit you around this time of year in search of gifts and hospitality, but plants that survive off the 'generosity' of others. I've blogged about a few of them already.

The kiss-inducing mistletoe (Viscum album) is a parasite, or partly so. We call it a hemiparasite in recognition of it producing its own sugars through photosynthesis, but drawing most of its water and nutrients from the host plant.

The Western Australian Christmas Tree, Nuytsia floribunda, does the same. These hemiparasites can be attached to roots or stems. Other mistletoes are fully parasitic, such as the leafless Tristerix aphyllus growing on cactus stems.

The tiny Christmas Lantern, Thismia, is parasitic on fungi and grows entirely under the leaf litter - flower and all. Due to its obscure habit, it is unlikely to adorn a festive table, although its flower is a Christmassy red colour.

This next one isn't so beautiful in form or colour. It's the Lesser Broomrape, Orobanche minor, photographed here in the Melbourne Gardens, in early November.

The Orobanchaceae is a relatively large family (around 2000 species) of root parasites, many - such as this one - having no chlorophyll (so no photosynthesis and entirely dependent on their hosts). The Ivy Broomrape, Orobanche hederae, was one I saw commonly in the UK, and this Lesser Broomrape pops up here and there around Melbourne and much of southern Australia.

There are 140 species of Orobanche with only a variety, of Orobanche cernua, native to Australia. The Lesser Broomrape (above) was introduced into Australia from Europe, presumably inadvertently as cargo on one of its many hosts. In this case it seems to be attached to the roots of a Plectranthus.

But today I want to make special mention of a weird desert plant called Cistanche. This genus came to my attention most recently in a talk at the Chinese Association of Botanic Gardens meeting in Chongqing, China, in October. Unfortunately the presentation was in Mandarin but I could at least marvel at the photographs (the image above shows a warty underground stem, the picture at the top of the post, Cistanche deserticola in flower).

The genus extends from Europe into Asia (or vice versa...), with five species native to China. Medicines are extracted from a few of the Chinese species but Cistanche deserticola ('desert loving') is the mostly commonly used: the Flora of China states that "the stems are used medicinally for enriching the blood, invigorating the kidney and strengthening yang sexuality, and relaxing the bowels". It has become increasingly popular in recent years as an aphrodisiac, and more recently, shown to have potential as an anti-colon cancer therapy. 

I gathered from the visuals in the talk that Cistanche deserticola, or Desert Broomrape, is grown extensively in dry parts of China. It was planted in long rows, near to and perhaps parasitic on a plant that looked like Tamarisk (Tamarix) but was more likely to be Saxaul (Haloxylon ammodendron).

Huge quantities - there were lots of massive numbers and illustrations of harvest bounty - of the root are used for medicines. An annual conference is held each year in China to discuss the genus and its cultivation. 

A newspaper article from China in 2009 argued that cultivating and harvesting Desert Broomrape made the planting of Saxaul economic. Saxaul is a drought-resistant shrub used to stabilise sandy deserts in western China. However without the money brought in through the Broomrape, there is no financial incentive, or ability, to plant Saxaul.

Due to my linguistic limitations I don't know the full environmental and economic consequences of this kind of farming but Broomrape is clearly big business in China and the rows upon rows of pine-apple-like flowering stems are impressive. I just wished I'd taken more pictures during the talk.

Anyway, Merry Christmas or happy festive season, and may your bowels be relaxed and all other desires satisfied.

Images: the top image is from Urbol, the picture of the harvested root from Rainbow, and the Christmas mistletoe, from The Sun.

Tuesday, 12 December 2017

Tough vine with tenuous grip on Madeira

The Madeira Vine, Anredera cordifolia, grows happily in Clifton Hill (Australia), Christchurch (New Zealand) and, in these images, in Chongqing (China). It also thrives in places not starting with 'c', particularly if there is a fence or shed to clamber over. But does it grow in Madeira, the group of four islands to the west of Morocco and part of Portugal?

If you don't know this vine, its a vigorous climber with shovel-shaped leaves and in spring dangling clusters of small white to purple flowers. In Chongqing, where I took these photos, it was a common covering of street-side retaining walls and buildings. Often weedy and neglected, but also celebrated and an occasional selfy background in places such as this (highly recommended) coffee joint called  Lazyfish, in the Chongqing suburb of Eling.

At first I couldn't remember its name so my Chinese friends whipped out their plant identification app (I couldn't find or load this app due to language incompatibilities on my phone). Which worked, confirming for us that this was the notorious Madeira Vine.

So what about Madeira? Well, as explained by Arthur Lee Jacobson, despite the connection with Madeira in its English (and Spanish and French) common name, it is native to the central parts of South America (including Bolivia, Paraguay, Uruguay and parts of Brazil and Argentina).

It was introduced into the UK in 1835 and in southern Europe even earlier, soon becoming 'naturalised' through much of Europe. Jacobson doesn't know why it gathered up the descriptor Madeira but one account he cites does suggest the plant was first established in Madeira before it made its way back to the Americas.

So perhaps, and I don't know, it just happened to have been noticed in Madeira by those who ended up coining and promulgating the common name in the rest of Europe. That's the way these things can happen.

In Australia, and I gather many other places, it doesn't set viable seed, instead relying on subterranean and aerial tubers - the latter, best described as knobbly, are produced where the leaves join the main stem. That form of reproduction and dispersal serves it well. It is an aggressive and damaging weed throughout much of Australia and New Zealand, and elsewhere in the world.

Madeira Vine can smother and kill native vegetation and in fact the knobbly tubers may be part of the problem. It has been suggested the weight of these may be responsible for the collapse and ultimate death of the host plant.

Anredera belongs to a rather obscure and small (four genera and about 20 species) family called Basellaceae. Nothing to do with the culinary Basil, but another member of the family, Basella alba, is eaten as Malabar Spinach, and even our Madeira Vine is edible, as Okawakame or Land Spinach in Japan. Kirsten Bradley, on her Milkwood site, makes a spirited case for eating and partly tolerating (if not cultivating) this weedy species.

So the leaves are useful, as a spinach substitute. The flowers don't serve much purpose for the plant but they are not unattractive when white, and more so when they mature to that brownish purple colour not uncommon in mosquito and midge orchids in Australia.

Notes: Map of actual (red dots) and potential (blue shading) of Madeira Vine in Australia is from a Queensland Department of Agriculture and Fisheries Fact Sheet. The spelling of 'distribuiton' is theirs.

Tuesday, 5 December 2017

Toxic plant suit cool in the tropics

I've posted before on the poisonous properties of this tree but not on its contribution to farming apparel. Here is a suit fashioned from the bark of Antiaris toxicaria, an outfit I gather worn (traditionally) by field workers in the tropical Xishuangbanna Prefecture, in the far south-west of China.

This display was part of a touring exhibition at Nanshan Botanical Garden in Chongqing, curated and supplied by Xishuangbanna Tropical Botanical Garden. The Director of Xishuangbanna, Professor Chen Jin, told me that pants and shirts made from the bark of Antiaris toxicaria are both cooling and comfortable.

It set me wondering what other clothes are made from plants. Cotton of course, the fluff from a Gossypium fruit. Us hipsters probably have a bambooflax (linen) or hemp shirt - or pair of socks - in the (distressed) wardrobe. Pretty much anything with fibres can and has been used, from pineapples (piƱa) to a mallow called Corchorus (jute).

Then there is rayon, which is a factory product but made from cellulose primarily sourced from the wood of trees.

I'm sure there are lots of other plants worn as clothing. I know leaves and bark form part of the ceremonial dress for various cultures around the world. The shoes, and all the other stuff in this next picture, are made from fungal threads (while fungi are more closely related to animals than to plants, we like to consider them honorary parts of a botanic garden). This display is in the foyer of the excellent Micropia museum in Amsterdam. 

There is seaweed of course. There is always a seaweed or another alga ready to solve the world's problems and kelp is as good a source of fibre as any land 'plant'. And to fit in with this post, let me point you to a 2010 article about seaweed clothes made in China.

Or if you prefer to knit your own, here is a wool-seaweed fibre blend. I do not in any way endorse the health or otherwise giving properties of this product, but you can find out all about 'seacell' here (and thanks to Vicki Kate Makes for the photograph below).

Are there any other plant(or algae)-sourced clothes as toxic as the suit from Xishuangbanna? Well you can make cloth from the fibres of nettle plants. It's called ramie. But then you can also eat nettles, if you cook them first (and in any case, the hairs on the nettle used - various species of Boehmeria - are not of the stinging kind).

I wouldn't eat anything made from the Antiaris toicaria tree but you might feel and look cool if your shirt is made from its bark.

Tuesday, 28 November 2017

Powerful perfume attracts city flower status

An 'extremely powerful apricot fragrance', according to Missouri Botanical Garden's Plant Finder website. 'Exceptionally fragrant flowers' writes Roger Spencer in his Horticultural Flora of South-eastern Australia. And an 'incredible smell of ripe apricots' says Sophie Thomson on Gardening Australia.

Apart from the apricot connection this is exactly what you would expect from a tree whose botanical name translates roughly as the 'fragrant perfume-flower'. We are talking about Osmanthus fragrans, the Sweet or Fragrant Olive, and related species.

Back in 2010, when I reported on my first experiences eating the flowers (and algae) of China, I mentioned Osmanthus as a flavouring for 'soups, desserts or what is called Osmanthus wine'. On my most recent trip to country, in October this year, I didn't detect any Osmanthus-flavoured foods but it was hard to miss the perfume and colour of their flowers in the streets of Chongqing.

While the Missouri Botanical Garden write-up says the flowers are 'not particularly showy', they are not unattractive and they are clearly visible. Apart from the Chinese Flame-tree (Koelreuteria bipinnata), which I'll return to in a later post, it was one of the few street trees expressing a splash of colour in October.

I expect the Osmanthus was at the end of its flowering season, and the pollinating insects had mostly done their work because while I was there the temperature dropped dramatically. They say there is no autumn in Chongqing and when I was there at the start of October we had a switch overnight (9-10 October) from hot and sunny low-30s, to rain and a maximum of 15 degrees.

In Melbourne (Australia) the weather would oscillate between these two extremes for a few weeks, or even months, and sometimes within a day. In Chongqing, I gather that was it. 'Winter' had arrived. 

So I saw the white and orange coloured forms of Osmanthus in sunshine and rain, summer and winter, streets and parks. You'll also find them near temples and in plenty of gardens from Chongqing to Chadstone (in Australia).

As the common  names imply, this is a relative of the Olive (Olea). The family Oleaceae has 29 genera, mostly from Asia but with some from Australia (e.g. Notelaea) and quite a few grown in our gardens, such as Ligustrum and Syringa.

We have five of the 35 species of Osmanthus growing in Melbourne Gardens, plus Osmanthus x fortunei, a hybrid bred in Japan between the commonly grown Osmanthus fragrans and Osmanthus heterophyllus

The trees I photographed in the Chongqing streets are most likely - he says consulting his trusty Horticultural Flora of South-eastern Australia (soon to be available on-line!) - Osmanthus fragrans. The orange flowered ones are I think the same species, but a form called aurtantiacus, which means 'orange coloured'. 

Those who know the genus better may correct me but with relatively large leaves, mostly entire edges but when toothed, very finely so, this seems a reasonable fit.

I understand Osmanthus fragrans is the 'city flower' - a concept I wish we could adopt (uniformly) in Australia - of Guilin (south of Chongqing) and a couple of cities near to Shanghai. Chongqing has the camellia I think. What would we chose for Melbourne?