Manaaki Whenua – Landcare Research plant ecologist Dr Bev Clarkson explains how some wetland plants have adapted to life in nutrient or oxygen-poor conditions.
Note: In this video, there is footage of a sundew feeding on a fruit fly. The Cape sundew (Drosera capensis) is an exotic sundew found in New Zealand.
Questions for discussion:
- What are adaptations?
- Why do plants like sundews and bladderworts need to capture insects for extra nutrients?
- What makes plants like kuta or raupō useful for insulation within the walls or thatching on a building?
Transcript
Dr Beverley Clarkson
The repo have special plants, because many plants in repo don’t grow in any other ecosystem, so they’re just confined to repo. Some examples are the carnivorous plants, for example, the sundews. They get their nutrients from insects that they trap in their hairs that are on their leaves. And other wetland plants are what we call bladderworts, so they have bladders under the water that trap aquatic insects within their bladders and digest those and get their nutrients from those. So like most wetland plants, they are adapted to the wetland conditions.
Generally, plants that grow in uplands, in non-wetlands, have air spaces down by their roots so they can get the oxygen in through the root system, but wetlands cannot do that. For example, the swamp maire and other species have breathing roots above the surface that get the oxygen straight into the roots. Some wetland species are almost always in permanent water. There’s very little oxygen within water, so many plants have air spaces within their stems or their leaves. For example, this wīwī or Juncus has got aerenchyma. These are just cells with big air spaces in them, and oxygen can come in, down through the air spaces and down to the roots, and that survives very nicely in permanent wet water. Raupō is another good example – it has large aerenchyma. Kuta is another plant that you typically find on the edge of lakes, and that also has aerenchyma.
Iwi use a lot of these plants for thatching because they’re soft and they hold the moisture or the warmth within the walls. They’re also used for mattresses, for packing, for lying on, and other things like pōtae.
Acknowledgements
Forked sundew Drosera binate photo, John Tann, CC BY 2.0
Photo, forked sundew Drosera binata in hand, Harry Rose CC BY 2.0
Footage Drosera capensis eating a fruit fly, Scott Schiller, CC BY 3.0
Fairy apron bladderwort photo, harrylurling, CC BY-NC 4.0, sourced from iNaturalistNZ
Fairy apron bladderwort, close-up photo of ‘bladders’, Jean Jack, CC BY-NC 4.0, sourced from iNaturalistNZ
Yellow bladderwort photos, Tangatawhenua, CC BY-NC 4.0, sourced from iNaturalistNZ
Photo, swamp maire, chauncy, CC BY-NC 4.0. Sourced from iNaturalistNZ.
Photo, swamp maire roots, Jacqui_NZ, CC BY-NC 4.0. Sourced from iNaturalistNZ.
Photo of kuta, Mieke Kapa; Illustration, sourced from Te Reo o Te Repo – The Voice of the Wetland
Historical photo, raupō hut, by Hubert Earle Vaile, 16–23 Nov 1905, Auckland Libraries Heritage Collections 2-V612
Hats woven from kuta, Dr Priscilla Wehi
The Voice of the Wetlands
The handbook Te Reo o Te Repo – The Voice of the Wetland forms the basis of the collection of resources funded by Manaaki Whenua – Landcare Research and MBIE’s Unlocking Curious Minds initiative.
