Bone-chilling botany

We sample the spookiest sights and smells at Cambridge University's Botanic Garden...
04 November 2022

Interview with 

Sally Petitt, Cambridge University Botanic Garden


African crawler plant


For a belated Halloween treat, the Naked Scientists were invited to take a tour of Cambridge University’s Botanic Garden, but with a terrifying twist. An opportunity Will Tingle and James Tytko thought too good to miss…

James - Will, another day, another expedition you've led us on. Where are we and what are we doing this time?

Will - Well, James, I've come to scare you senseless. We've been very kindly invited to Cambridge's Botanic Garden to sample some of their spookiest, most Halloween appropriate plant life.

James - Is the anticipation here that, the plants themselves, they look scary, or they do something scary?

Will - Maybe even a bit of both.

James - Well, yeah, Good luck scaring me with plants.

Sally - Hello, I'm Sally Pettit. I'm head of horticulture here at Cambridge University Botanic Garden.

James - And we're here on our whistle stop tour of all things spooky and horrible here at the Botanic garden - not that anything's that horrible here - what have we got in front of us ? It's like a purplely coloured plant. It's covered in little hairs they look like, and it's got a sign next to it which says, "Smell me."

Sally - Well, this is a very rare orchid. It's called Bulbophyllum phalaenopsis. So it's quite a mouthful. And it's flowered on cue for Halloween. It sort of has a sinister coloring, that deep purple-y, red-y colouring with those little yellow hairs on each of those little flower hoods. But it's most intriguing aspect or facet is really the smell that makes it very Halloween-y

James - Shall I get stuck in?

Sally - Oh yeah, get stuck in.

James - Oh, it's pretty nasty <laugh>. It's mouldy.

Sally - It's the plant giving off a scent, which some people think is a bit like drainage. Some people think it's rotting flesh, but it's actually there to attract pollinators. So it'll be pollinated by something obscure - beetle or a fly - that really is drawn to that rotting flesh smell.

Will - Well, we are stood here in front of what you've dubbed the eyeball plant.

Sally - We are looking at the seed cluster of this extraordinary climber that scrambles up through host plants in Africa. And it's basically the seeds in a head. So this would've been the flower head and it's developed the seeds and you've got this kind of white outer, the fleshy part of the fruit. And popping out from the center of those are these black beady seeds, and together it looks like somebody's bursting eyeball.

Sally - So this is a small houseleek. Latin name is Sempervivum - which means always living - and arachnoideum from spider. And it's something that grows through the Alps, a European species. So they make these fantastic rosettes and you can see neighbouring plants have these very succulent large leaves, but no cobwebbing. This one's particularly adapted to grow this cobweb, which will help protect it.

Will - Very apt. What is it protecting it from?

Sally - It would just be protecting it from predation by something that may otherwise go along and just gnaw at those leaves. I can't imagine that there's a lot high up in the Alps that's going to go along and graze on that. Story goes that they were grown on the roofs of houses to ward off evil spirits.

Will - Well, do you see any old spirits around here?

Sally - Get a few passing through.

Will - Fair enough.

James - Well, no exploration of Halloween themed vegetation would be complete without referencing pumpkins. Now these are a bit different from the pumpkins you might pick up in the supermarket. I don't think they're pumpkins at all actually. They just look like them. They're about the size of an eyeball as it happens.

Sally - So this is a member of the potato family, but it more closely resembles tomatoes, which are in the same family. And it's called commonly 'cannibals tomato.'

James - What's the story behind that name?

Sally - It comes from the South Pacific and story goes that cannibals of that region did use this as accompaniment when they were eating human flesh. What a great story.

James - A nice pairing, I'm sure.

Will - I wonder what it would taste like. Probably better than human flesh.

Will - You've got me in front of this maggot riddled eyeball here. What are you playing out?

Sally - This is a member of the Mulberry family. It's a plant called Broussonetia kazinoki. It's the Kozo paper Mulberry, so you can make paper from it. But I think the most interesting thing about this are the amazing fruits.

Will - They almost look like fingers coming out of the centre fruit in a way.

Sally - Oh, they do, don't they? They look as if they're like little fingers with tiny nails on them. But this is how this plant distributes its seeds. So these little orange, like almost pustules are actually the seeds.

Will - It's getting worse.

Sally - Birds come along and eat these. They're quite sweet. They're quite juicy and succulent, but they are just bonkers to look at.

Will - This is intense closure for me here. I've seen this fruit plant, whatever it is, around in the wild for about 10 years. I'd never known how to identify it. Could you please put me out of my misery?

Sally - This is a tree from North America called the Osage Orange or Maclura pomifera. So it is named after a William McClure who is a geologist. Pomifera describes the fruit because it in theory looks a bit like an apple, but it doesn't altogether look like an apple really. We refer to these as gardeners' brains, sort of a limey green, nearly yellowy green, and they have all these fantastic fissures across the surface. So it's quite rough and it does resemble a brain.

James - We've entered the spooky forest. This tree here, the colour palette especially reminds me of a zombie. The green flesh and then the haggard bark and then that tree over there is looking pretty ghosty. What part of the botanic garden are we in here?

Sally - We're in the Gilbert Carter Woodland. It's quite a naturalistic area of the garden. In spring we let all the cow parsley grow up, so it's all soft and lovely and quite daydreamy and yeah, this time of year, you lose all the grass. It highlights the trees, particularly when they lose their leaves as well. And you get these fantastic bark colorings and things.

James - A very distinct look to the trunk.

Sally - It's a slightly peeling bark. It is a dogwood. This is Wilson's Dogwood Cornus wilsoniana. And many of the dogwoods are renowned for their coloured stem. So they have brilliant reds and oranges as in our winter garden. But here, this is much more subtle. Yeah, just quite an unusual tree, but it just has that moodiness about it. .

Will - So James, are you suitably spooked after that chilling experience?

James - Well, yeah, just a big thanks to you actually, Will. I've very much enjoyed my time looking at all things scary and smelly in the plant world. I don't think Sally will mind me saying too much that she's got quite the imagination, doesn't she?


Add a comment