Tag Archives: dispersal

NZ fern colonises Australia, twice

4 February 2011 – 10.38am
Asplenium hookerianum

Hooker's spleenwort fern. Near Levin, New Zealand. (c) Leon Perrie.

It is not just people crossing the ditch – a little New Zealand fern has also emigrated to Australia, and not just once but twice.

This is the first known case amongst ferns or seed plants of the same species dispersing twice across the Tasman Sea.

Hooker’s spleenwort fern, or Asplenium hookerianum, is a close relative of the hen & chickens ferns. Hooker’s spleenwort is widespread and common in New Zealand, but rare in Australia, with only a few, small populations in each of Victoria and Tasmania.

DNA analyses of the populations of Hooker’s spleenwort were carried out by researchers from Te Papa, Massey University, and the University of Melbourne.

26 genetic variants were found in New Zealand, but only one each in Victoria and Tasmania. Not only are the Australian variants at the tips of the genetic family tree, they are more closely related to variants in New Zealand than to each other.

This research was recently published in the journal Australian Systematic Botany.  Email me if you would like a copy of the paper: leonp@tepapa.govt.nz

Many plant species are known to have dispersed across the Tasman Sea, in either direction. Numerous New Zealand species also occur in Australia (about 50% in ferns), and more have close relatives there. But, it remains an open question how common multiple dispersals within a species are.

By Leon Perrie | Posted in Ferns, Plants | Also tagged , , , , , , , | Comments (3)

Big travels for little ferns

22 July 2010 – 11.46am

Lindsaea are small dainty ferns that are easily overlooked. Three species are indigenous to New Zealand.

Recent DNA-based research (Lehtonen et al. 2010) implies that each got here independently; i.e., there were three separate dispersal events. This is because the three species in New Zealand are each more closely related to an overseas species than to each other.

The three indigenous New Zealand species are:

Lindsaea trichomanoides (also in Australia) is related to L. rufa of New Caledonia.

Lindsaea trichomanoides. (c) Leon Perrie.

Lindsaea viridis (only found in New Zealand) is related to a group of species occurring from Madagascar through Malesia to western Polynesia.

Lindsaea viridis. (c) Leon Perrie.

Lindsaea linearis (also in Australia and New Caledonia) is related to L. microphylla of Australia.

Lindsaea linearis. (c) Leon Perrie

This is a common pattern. Many New Zealand ferns are also indigenous elsewhere. Of the species only found in New Zealand, many are more closely related to overseas species than to other New Zealanders. This indicates a comparatively high level of immigration and emigration.

Lehtonen S, Tuomisto H, Rouhan G, Christenhusz MJM (2010) Phylogenetics and classification of the pantropical fern family Lindsaeaceae. Botanical Journal of the Linnean Society 163: 305-359.

More on the origins of New Zealand’s ferns.

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

Baby ferns

8 March 2010 – 12.43pm

A spot in my garden is being colonised by baby ferns.

The toppling of a gum tree last year created bare ground. After a few months, this has now been smothered by little ferns, the biggest only a few cm long.

Baby ferns. Photo by Leon Perrie. © Leon Perrie, Wellington.

Baby ferns are difficult to identify, but I suspect these are water fern (Histiopteris incisa) and ring fern (Paesia scaberula).

Each baby fern has arisen from a different spore, so many spores have fallen on this spot.  Yet, there are no adults of these species within at least 100m, and perhaps even a kilometre or so. Clearly there are a lot of fern spores blowing in the wind!

Ferns, like all terrestrial plants, have a two part life-cycle. This is more obvious in ferns because both parts are free-living.

The typical fern plant produces spores, and releases them into the wind. If the spores happen to land in a suitable spot, they germinate to produce a gametophyte.

Fern gametophyte, smaller than a fingernail. Photo by Leon Perrie. © Leon Perrie, Wellington.

The gametophyte produces eggs, which are held internally, and sperm, which disperse through any free water. Fertilisation produces a sporophyte – the typical fern plant.

Young fern sporophyte growing from the fertilised egg of a gametophyte. Photo by Leon Perrie. © Leon Perrie, Wellington.

More detail on the fern life-cycle.

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

About hooks, hairy legs and sedges!!

30 October 2009 – 11.03am

Tramping in New Zealand forests can be an enjoyable and very relaxing activity. However, if your legs are hairy, it could be a painful and very annoying experience. Camouflaged among ferns and ground orchids, hook grasses are waiting, ready to clasp to the hairs or clothing of any unwary tramper.

Hook grasses get their name from a hook-like structure which arises from the base of the ovary of each female flower.

hook&stigma

Detail of a receptive female flower of Uncinia zotovii indicating hook and stigmas. Photo by C.A. Lehnebach (c) Museum of New Zealand Te Papa Tongarewa.

 

This structure allows dispersal of the achene, a single seed produced by each female flower, to other sites by clasping to the hairs, or feathers, of any animal (or hairy tramper) passing by.

achene

Seed (achene) of a native hook sedge. Photo by C.A. Lehnebach (c) Museum of New Zealand Te Papa Tongarewa.

 

Flowers in Uncinia are unisexual, that is male and female reproductive structures are on separate flowers. In Uncinia, female flowers are at the base of the spike while male flowers are at the top.

spike-details-blog

Mature spike of Uncinia caespitosa indicating female and male sections. Photo by C.A. Lehnebach (c) Museum of New Zealand Te Papa Tongarewa.

 

Only female flowers have a hook. Male flowers are small and have three stamens, which quickly fall off after the pollen is released.

anther&filament

Male flowers of Uncinia and detail of stamens. Photo by C.A. Lehnebach (c) Museum of New Zealand Te Papa Tongarewa.

 

New Zealand is the diversity hotspot for Uncinia, however, little is known about their ecology and the actual number of species is still uncertain. Some species are so variable that it is possible they may consist of two or more species.

As part of my work in Te Papa I have investigated a group of morphologically variable Uncinia. The main goals of my study were to understand the cause(s) of this variability and to produce revised descriptions for these species to make their identification easier.

By Carlos A. Lehnebach | Posted in Plants, Sedges | Also tagged , , , | Comments (2)
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