Tag Archives: weed

Restoring our surrounds

16 June 2009 – 12.41pm

I went to a very interesting Wellington Botanical Society talk last night, by Paul Blaschke of Friends of Owhiro Stream. Paul was talking about their work revegetating the catchment of the Owhiro Stream in southern Wellington.

It stimulated an intriguing discussion about how and what we should be restoring, which in turn relates to what our goals for conserving biodiversity are.

Ecological restoration is a vexed issue, with many controversial aspects, so it was good to discuss, learn, debate, and think.

For instance, some people believe that only plants present in an area before humans arrived should be used in restoration.

Collections of plant specimens, like that held by Te Papa, can play an important role in establishing where plants are/were distributed.

Houpara, coastal five-finger, Pseudopanax lessonii, is native to the northern North Island, but not to Wellington. However, after being introduced by people, it now grows wild in Wellington (and many other parts of New Zealand outside its native range [http://blog.tepapa.govt.nz/2009/06/10/our-promiscuous-pseudopanax-plants/]). There are now a reasonable number of New Zealand plants occurring wild outside their indigenous distributions, entirely as a result of human activities. Photo by Leon Perrie. (c) Leon Perrie, Wellington.

Houpara, coastal five-finger, Pseudopanax lessonii, is native to the northern North Island, but not to Wellington. However, after being introduced by people, it now grows wild in Wellington (and many other parts of New Zealand outside its native range). There are now a significant number of New Zealand plants occurring wild outside their indigenous distributions, entirely as a result of human activities. Photo by Leon Perrie. (c) Leon Perrie, Wellington.

Other people go even further when considering restoration, saying that only locally-derived material should be used.

Photo by Leon Perrie. (c) Leon Perrie, Wellington.

Mahoe, Melicytus ramiflorus, occurs indigenously throughout most of New Zealand. For restorations in, say, Wellington, should only material derived from local-Wellington sources be used? Or, is it okay to use mahoe plants from anywhere? Photo by Leon Perrie. (c) Leon Perrie, Wellington.

But, is it practically possible to ensure such ‘eco-sourcing’? Do the costs outweigh the benefits?

And, what geographic scale is appropriate for eco-sourcing? Should plants be from the same province, river-catchment, …, or hillside?

Is it already too late, at least for some species/communities/regions, to even attempt to ensure that pre-human patterns are preserved? Has the colloquial horse already bolted? Are the ‘genes’ out of the bottle?

And, on a temporal scale, what are the implications from past and future climate-change? Many lowland New Zealand plants were more widespread during past warmer periods (and, similarly, much restricted when it was colder). Indeed, many warmth-loving plants were eliminated completely from New Zealand during the Ice-Age. Given the dynamism of biodiversity, what are appropriate parameters for restoration targets?

Managing ‘nature’ is often a tricky business…

By Leon Perrie | Posted in Plants | Also tagged , , , | Comments (0)

Our promiscuous Pseudopanax plants

10 June 2009 – 1.43pm

New Zealand’s plants have a bit of a reputation for pronounced promiscuity. There is supposedly a high rate of hybridisation, or individuals of one species breeding with individuals of a different species.

I’m not entirely sure that this reputation is nationally deserved. Nevertheless, a striking example of hybridisation occurs in Pseudopanax, which is one of the groups I am researching; indeed, their hybridisation is what attracted me to them!

Two of the species – Pseudopanax crassifolius, horoeka, lancewood, and Pseudopanax lessonii, houpara, coastal five-finger – hybridise wherever they occur together, be this in the wild or in cultivation. 

The leaf on the left is of coastal five-finger, that on the right is from a juvenile lancewood, and the three in between are from different hybrid individuals. Photos by Leon Perrie. Montage (c) Museum of New Zealand Te Papa Tongarewa.

The leaf on the left is of coastal five-finger, that on the right is from a juvenile lancewood, and the three in between are from different hybrid individuals. Photos by Leon Perrie. Montage (c) Museum of New Zealand Te Papa Tongarewa.

More images of leaves from hybrids are here.

There are several other five-finger and lancewood Pseudopanax species in New Zealand. However, despite their very different appearance, most of the hybridisation I have seen appears to be between lancewood and coastal five-finger, and we are using genetic analyses to determine just how much gene-flow occurs between them.

 

Juvenile lancewood, horoeka, Pseudopanax crassifolius. Photo by Leon Perrie. (c) Leon Perrie, Wellington.

Juvenile lancewood, horoeka, Pseudopanax crassifolius. Photo by Leon Perrie. (c) Leon Perrie, Wellington.

Adult lancewood, horoeka, Pseudopanax crassifolius. Photo by Leon Perrie, Curator. (c) Museum of New Zealand Te Papa Tongarewa.

Adult lancewood, horoeka, Pseudopanax crassifolius. Photo by Leon Perrie, Curator. (c) Museum of New Zealand Te Papa Tongarewa.

 

Coastal five-finger, houpara, Pseudopanax lessonii. Photo by Leon Perrie. (c) Leon Perrie, Wellington.

Coastal five-finger, houpara, Pseudopanax lessonii. Photo by Leon Perrie. (c) Leon Perrie, Wellington.

Some of the hybrids are easy to identify, but others closely resemble one or other of the parental species. Any individual with leaves that look like those of lancewood but with two or more leaflets is actually a hybrid. Coastal five-finger always has broad leaflets.

Wellington’s Otari-Wilton’s Bush has a garden display of lancewood, coastal five-finger, and their hybrids, for 2009.

Lancewood occurs naturally throughout New Zealand. Coastal five-finger and the hybrids are native only to the coasts of the northern North Island (about Raglan and Gisborne northwards), but are frequently cultivated elsewhere. Coastal five-finger and the hybrids have escaped from cultivation, effectively becoming weeds, in many places outside their native distribution.  They can be very invasive.

Distribution maps for (A) lancewood, (B) coastal five-finger, and (C) their hybrids. Circles indicate natural distributions, and were compiled using data from the AK (Auckland Museum), CHR (Landcare Research), NZFRI (Scion), and WELT (Te Papa) herbaria. Squares for coastal five-finger and the hybrids indicate their ‘weedy’ distribution, this being a preliminary assessment based on my observations.

Distribution maps for (A) lancewood, (B) coastal five-finger, and (C) their hybrids. Circles indicate natural distributions, and were compiled using data from the AK (Auckland Museum), CHR (Landcare Research), and WELT (Te Papa) herbaria. Squares for coastal five-finger and the hybrids indicate their ‘weedy’ distribution, this being a preliminary assessment based on my observations.

By Leon Perrie | Posted in Plants, Pseudopanax | Also tagged , , , , | Comments (10)

WEED ALERT – watch for horsetails!

26 May 2009 – 6.15pm

An infestation of a giant horsetail, Equisetum hyemale, has been found near Levin. It was spotted by eagle-eyed Department of Conservation staff. They gave us a specimen for Te Papa’s herbarium collection of dried plants.

An unimpressed Jon Terry (DOC) with the Levin infestation of Equisetum hyemale. Photo by Clayson Howell, DOC. Copyright Clayson Howell, Wellington.

An unimpressed Jon Terry (DOC) with the Levin infestation of Equisetum hyemale. Photo by Clayson Howell, DOC. Copyright Clayson Howell, Wellington.

 

Stems of Equisetum hyemale, with the terminal ‘cones’ that produce spores. Photo by Clayson Howell, DOC. Copyright Clayson Howell, Wellington.

Stems of Equisetum hyemale, with the terminal ‘cones’ that produce spores. Photo by Clayson Howell, DOC. Copyright Clayson Howell, Wellington.

No horsetail species occur naturally in New Zealand, but several have been purposefully or accidentally introduced. Because they are invasive weeds, smothering and displacing other plants, all Equisetum species are ‘Unwanted organisms’ in New Zealand. They are also listed in the National Pest Plant Accord which seeks to “prevent the sale, distribution, or propagation” of specified pest plants in New Zealand.

Regional Councils should be notified if horsetails are found in the wild, especially if they are suspected of being new populations. Environment Southland and Weedbusters have useful information available on the web.

Equisetum hyemale is native to temperate areas of the northern hemisphere. In New Zealand, we knew it had gone wild in Christchurch but it has apparently also become weedy in Whangarei, Auckland, New Plymouth, Levin, Motueka, Greymouth, Fox River, and multiple sites in Southland (Clayson Howell pers. com.). Most of these occurrences are fortunately relatively local.

Two other horsetail species are adventive in New Zealand. Equisetum fluviatile has been found once in the wild near Hamilton. The other, Equisetum arvense (field horsetail) is, unfortunately, much more widespread. In the Rangitikei and Manawatu areas, for instance, it has well and truly escaped and gone wild. It is usually found around streams and other damp places.

Equisetum arvense is much smaller (up to 80 cm tall, but often much shorter) and is branched, whereas Equisetum hyemale is unbranched. Photo by Jean-Claude Stahl, Natural Environment Imager. Copyright Museum of New Zealand Te Papa Tongarewa.

Equisetum arvense is much smaller (up to 80 cm tall, but often much shorter) and is branched, whereas Equisetum hyemale is unbranched. Photo by Jean-Claude Stahl, Natural Environment Imager. Copyright Museum of New Zealand Te Papa Tongarewa.

 

Distribution of Equisetum arvense in New Zealand as indicated by verifiable specimens in Te Papa’s herbarium. Te Papa’s collection is an under-representation of this species’ full extent, having been recorded by others from Auckland, Napier, New Plymouth, Christchurch, and Dunedin.

Distribution of Equisetum arvense in New Zealand as indicated by verifiable specimens in Te Papa’s herbarium. Te Papa’s collection is an under-representation of this species’ full extent, having been recorded by others from Auckland, Napier, New Plymouth, Christchurch, and Dunedin.

To help with understanding the distribution of these weeds in New Zealand, we would appreciate specimens of horsetails from localities not already represented in our collection. Any wild Equisetum hyemale or Equisetum fluviatile is of interest, although Equisetum arvense is most likely to be encountered (see map for our present holdings). However, if collecting (or attempting to destroy) horsetails, please take care not to inadvertently spread them, as they can propagate from even fragments of their underground stems.

Horsetails are an ancient and now evolutionary isolated group; they are more closely related to ferns than to any other living plant groups. They once were significant components of the world’s forests, but now only about 15 species survive. They occur naturally in all parts of the world except Australasia (and Antarctica!).

By Leon Perrie | Posted in Ferns, Plants | Also tagged , , | Comments (2)

Weedy ferns

23 March 2009 – 12.02pm

Chris Horne of the Wellington Botanical Society recently sent me a fern frond they collected on one of their trips. Although the frond is small and lacking the diagnostic reproductive characters, I think it is the introduced holly fern (Cyrtomium falcatum). It looks like the shining spleenwort (Asplenium oblongifolium), but the flanges, or ‘teeth’, of the frond segments are distinctive (amongst ferns in New Zealand).

Holly fern, Cyrtomium falcatum, in cultivation.

Holly fern, Cyrtomium falcatum, in cultivation.

Holly fern and shining spleenwort can be readily distinguished when mature. The reproductive structures of the holly fern resemble those of the shield ferns (Polystichum), to which it is related, while the shining spleenwort has typical spleenwort reproductive structures.

The sori, or reproductive structures, on the underside of fronds of holly fern, Cyrtomium falcatum, on the left and shining spleenwort, Asplenium oblongifolium, on the right.

The sori, or reproductive structures, on the underside of fronds of holly fern, Cyrtomium falcatum, on the left and shining spleenwort, Asplenium oblongifolium, on the right.

Holly fern is native to Asia, but it is sporadically cultivated in New Zealand, and it has become weedy in several parts of the country. Steve Benham wrote an article for the Auckland Botanical Society Journal (v.63 (1), pp.25-27) suggesting gardeners should be dissuaded from cultivating holly fern in the Northland and Auckland regions, because of its invasiveness in that part of the country.

It is certainly a fern that should be monitored, so it would be good to get reports of holly fern growing wild.

Two other weedy ferns to keep an eye out for are common polypody, Polypodium vulgare, and the male fern, Dryopteris filix-mas.

The common polypody, from Europe and Asia, is a common weed on Banks Peninsula, and it has recently been found in Wellington (near Plimmerton) and Marlborough (near Kaikoura and near Hanmer Springs).

It looks like the native hound’s tongue, Microsorum pustulatum, but can be distinguished by its frond being dissected right to the stem of the frond. Polypodium vulgare can be a terrible, smothering weed, so it is important that it is stopped from spreading further. Regional Councils should be notified of any additional localities.

caption

Fronds of common polypody, Polypodium vulgare, on the left and hound's tongue, Microsorum pustulatum, on the right. The blue arrows indicate the difference in frond dissection.

The male fern, Dryopteris filix-mas, is also from Europe, and has established in many parts of New Zealand. I have been amazed at how widespread it is in the South Island, but I haven’t collected it as often as I should have, and Te Papa’s collections don’t do its invasiveness justice. Male fern is unusual in that it can invade relatively intact native forest, making it a formidable weed.  A very similar species, Dryopteris affinis, is also weedy in New Zealand.

Male fern

Male fern, Dryopteris filix-mas.

Distribution of male fern, Dryopteris filix-mas, in New Zealand, based on specimens in Te Papa's WELT herbarium. Note that this is a significant under-representation.

Distribution of male fern, Dryopteris filix-mas, in New Zealand, based on specimens in Te Papa's WELT herbarium. Note that this is a significant under-representation.

I would be interested in reports of these species and other introduced ferns growing wild in New Zealand. This will help us better understand their invasiveness. Please contact me at leonp@tepapa.govt.nz, or 04 381 7261, or Leon Perrie, Te Papa, PO Box 467, Wellington.

By Leon Perrie | Posted in Ferns, Plants | Also tagged , , , , , , , , , | Comments (7)
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