Tuesday, 14 March 2017

Maple Twist is no Monkey's Hand

Apart from the absence of red simian-like floral parts, Maple Twist makes me think of Monkey's Hand Tree. There's the big downy leaves (as above!), the chunky flowers with an ornate centrepiece and the soft fragility of the trunk and stems.

As it turns out, Pterospermum acerifolium is indeed closely related to Chiranthodendron pentadactylon (the scientific names being informative if a little cumbersome).  They both belong to what was once Sterculiaceae (think Brachychiton) and is now Malvaceae (think Hibiscus plus now Brachychiton). The flower turns out to be more different than I thought, but we'll get to that later, like I did when I discovered this plant in Melbourne Gardens.

Maple Twist is also called Dinner Plate Tree on account of the big leaves, which are in fact used to hold or to wrap less savoury things like tobacco. Where it grows naturally - India and southern China, southwards to the Malaysian Penninsular - it gets called Bayur Tree, Machukunda, Bayog, Kanakchampa and more.

Most parts of the plant, including the flowers, are used in India for traditional medicine, to treat ailments from cancer to small pox. In recent years there has been a steady stream of scientific papers (e.g.) demonstrating antibacterial, antioxidant and other medicinal activity in, particularly, leaves and bark. The flowers are mostly used in a tonic, for treatment of various internal and external wounds, while the downy hairs on the undersurface of the leaves are said to prevent bleeding (as well as provide a handy tinder for starting fires).

The leaves are, as the species name suggests, shaped like (large) maple leaves. In dryer climates the tree is deciduous for a short time. When I photographed our Melbourne Gardens specimen, growing among a fine collection of araucarias from New Caledonia, there were plenty of dry leaves on the ground below.

The white flowers, like the red flowers of the Monkey's Hand Tree, attract bats as pollinators. But close up, they are not remarkably similar (see my post from November 2013) . What I had thought - at a distance of a few metres (the flowers are high in the tree) - to be something like the monkey hand of Chiranthodendron turned out to be the main part of the flower, with petals. The sepals (the layer outside the petals) are pealed back in the mature plant, like a banana skin.

In Monkey's Hand Tree, the petals and sepals seem glued together (I called them, naively perhaps, simply 'sepals' in my 2013 post) around the centre-piece which often drops from the flower. In Maple Twist, the petals and inner parts are more likely to fall together to the ground. You can see some of the detail here, but remember I've had to photograph this from a distance. I'm assuming the inside bits of the flower somehow conjures up the 'twist' part of Maple Twist. Maybe.

What you can't see, or detect, is the flowers producing a soft perfume. Mostly at night as an extra attractant for those bats but it also appeals to humans - the spent flowers are used as a fragrance and deodoriser for stored clothes and linen.

The fruits are large and 'cucumber-shaped', but given they persist on the tree for up to a year and I could see none on ours, it seems our trees don't set seed. If they did, the seed would be winged, living up to the genus name which means exactly that (winged seed).

This is a tropical to subtropical tree, but from sometimes higher elevations where temperatures can be lower and rainfall higher. They tolerate a dry season of up to seven months so perhaps they'll survive conditions in Melbourne in 2090.

It's grown widely around the world but mostly in Asia and nearby, and seldom, I think, in Australia. At least in the south. Although they can grow in areas with low rainfall, they tend to do best near a water body of some kind. Our tree is next to the Nymphaea Lily Lake and its roots no doubt take advantage of that situation.

Note: I must thank Stuart Williams (@stuartwilliams_) for alerting me to this species. Stuart posted a picture of the flower on Twitter, 23 December 2016, later remarking that it was taken in Melbourne Gardens. Thanks to these tweets I tracked it down on our census, and to this specimen!

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