Tim EntwisleMouse eating plant in unspectacular flower

I have little interest in rodents eating plants with unattractive flowers, but I’m intrigued by plants that eat mice, whether or not they have showy blooms.

Flowers on Nepenthes truncata, one of the world's bigger pitcher plants

Flowers on Nepenthes truncata, one of the world’s bigger pitcher plants

 

In this case the plant is Nepenthes truncata, one of the world’s bigger pitcher plants. The mouse is a house mouse but that’s not the point of this post. Let’s just say the pitchers on this pitcher plant are large enough to – and have been proven to – catch a mouse. Whether the plant really wants such a large mammal in its digestive system is unclear.

We grow a single specimen of Nepenthes truncata in our dinky Tropical Glasshouse at Melbourne Gardens. It’s a large plant, many years old, and in early September it was in full flower.

Nepenthes truncata in the Tropical Glasshouse at Melbourne Gardens

Nepenthes truncata in the Tropical Glasshouse at Melbourne Gardens

 

Not a flower to brighten a room perhaps but you might think at least we will soon have fruits, and seeds, and possibly a nursery fully of baby pitcher plants. Well, that isn’t going to happen. Take a close look at these flowers and you’ll notice they seems to consist mostly of a brain-like yellow sphere on a short stalk. Those yellow bits are the anthers, containing pollen.

Nepenthes truncata flower

Nepenthes truncata flower

Close-up of male flowers on Nepenthes truncata

Close-up of male flowers on Nepenthes truncata

 

What’s missing from these flowers are the female parts. To find those you need another specimen, and the right kind of other specimen, of Nepenthes truncata. This species, like all Nepenthes, has either male or female plants, and not both. Great for cross-pollination and encouraging genetic mixing and diversity, but rubbish for horticulture.

That said, you’ll find this species relatively commonly in a carnivorous plant enthusiast’s collection. That’s presumably because seed is readily available, even though hard to move between countries due to the constraints of CITES – the Convention on the International Trade in Endangered Species of Wild Flora and Fauna.

The reason for the CITES ban is (as Carlo Ballistrieri from New York reminded me when this story was first posted) because trade in an organism could lead to the species becoming rare and threatened, or more so, in its natural habitat.

This species is already rare in nature, growing naturally only in lowland (230-600 metres above sea level) forests of north-eastern Mindanao, in the Philippines, where it scrambles through jungle vegetation. It was named from two fragmentary collections and is still poorly known in the wild, supporting its listing as Endangered in the Red List of flowering plants.

Young leaf on Nepenthes truncata

Young leaf on Nepenthes truncata

 

Our plants are flowering well, if not attractively or successfully (in terms of the reproduction), but the mature pitchers are now fading. Once the plant has got over its unfulfilled flowering, it can reinvest in the new pitchers just starting to form on the tendrils at the end of its younger leaves.

 

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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

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