Tim EntwisleChiranthodendron pentadactylon

Chiranthodendron pentadactylon (so good I’m posting it twice). I mentioned this fantastic (in all senses of the word) plant in my late October blog post about Dunedin Botanic Garden. When I returned to Melbourne I found it in flower in my very own Royal Botanic Gardens, and when I bragged about it on Facebook I was told I would have seen it also in Sydney’s Royal Botanic Gardens when that was my home territory.

Chiranthodendron pentadactylon

Chiranthodendron pentadactylon

So it’s not uncommon. But it remains fantastic. Just take a look at the flower and try and work out what is going on. The velvety outer surface of the flower is typical of its family Sterculiaceae, or a broadly circumscribed Malvaceae if that’s your preference. The structure of the flower, though, isn’t like any Brachychiton or Lasiopetalum, typical members of this family (which also includes chocolate, Theobroma).

Chiranthodendron pentadactylon

Chiranthodendron pentadactylon showing flowers and foliage

This is a picture of the Kurrajong (Brachychiton populneus), also in flower in the Royal Botanic Gardens. Not one of the hairiest members of the genus, or family, but you can see the cup-like flower which is a theme I’ll return to.

Brachychiton populneus

Brachychiton populneus

The common names for Chiranthodendron pentadactylon are evocative – Monkey’s Hand Tree, Devil’s Hand Tree or simply Mexican Hand Tree (according to Wikipedia it is known locally as árbol de las manitas, the tree of little hands, or mācpalxōchitl, the palm flower) – but its botanical name is equally beguiling: Chiranthodendron means ‘hand-flowering tree’ and pentadactylon means ‘five-fingered’.

So clearly something looks like a hand! That something is actually the male part of the flower, a group of five stamens fused together at the base. In this picture each stamen is bearing a line of yellow pollen.

Chiranthodendron pentadactylon showing the line of yellow pollen

Chiranthodendron pentadactylon showing the line of yellow pollen

Chiranthodendron pentadactylon, showing the curved style

Chiranthodendron pentadactylon, showing the curved style

 

 

Between two of the fingers of this 5 cm long ‘hand’ you can see the curved stalk of the female part of the flower, the style. There is only one hand per flower. If you remove the ‘hand’, you are left with a cup of velvety petal-like structures called sepals, the outer layer of most flowers. The petals themselves are missing, as they are in most Sterculiaceae.

 

 

 

Chiranthodendron pentadactylon, showing the velvety sepals

Chiranthodendron pentadactylon, showing the velvety sepals

This tree is native to wetter areas of Guatemala and southern Mexico, but grows and flowers happily in Melbourne, Sydney and Dunedin! As you’d expect in a flower of this size and robustness, the pollinators are bats and birds, attracted by nectar in the base of the sepal cup. For them the hand is just something to brush against, getting in the way of their feasting. For the flower, it is presumably an attractive bit of advertising as well as good way to dump pollen onto animal visitors.

Now isn’t that just fantastic.

Like this post? Why not share it with a friend?


Tim Entwisle

About Tim Entwisle

Dr Tim Entwisle is a scientist and scientific communicator with a broad interest in plants, science and gardens, and Director & Chief Executive of Royal Botanic Gardens Victoria. Previously he was Director of Conservation, Living Collections & Estates at Royal Botanic Gardens Kew and prior to that, Director of Sydney’s Royal Botanic Gardens for eight years. Read Tim's full blog at Talking Plants

6 thoughts on “Chiranthodendron pentadactylon

  1. I agree Tim, what a wonderfully mellifluous name! And such an interesting flower. But is it actually quite small? Or are those leaves gigantic?

  2. Somewhere in between Catherine! The leaves are big and the flowers are moderately sized…. The hand-like part of the flower is about 6-10 cm long, like a small baby (or primate) hand.
    Tim

  3. So much movie potential in this plant Peta.

  4. Stuart Read on said:

    Tim I’d hardly call it ‘not uncommon’- it IS uncommon. I’ve only seen it in Wellington BG; Sydney & Melb. and Dunedin BGs – hardly ‘suburban’ as yet. Agree wonderful tree and intriguing – leaves as well as floral structures – and golden Brachychiton-esque down on everything, esp. when young. Mexico seems full of wonders! cheers

  5. Not uncommon in botanic gardens, as my recent experience showed. But true, Stuart, it could hardly be called common! Surprising though – pretty tolerant if it can grow in Sydney, Melbourne and Dunedin (and Wellington..) Must get to Mexico soon to see more of its flora…

Leave a Reply (no need to register)