ARTICLE : Asplenium lyallii in Wellington

 Asplenium lyallii in Wellington

We recently saw the fern Asplenium lyallii (Figures 1 & 2) on Wright Hill, Karori, which led us to wonder how common this species is in the immediate Wellington area?   Not very, it would seem.   There are only three collections in WELT, Te Papa’s herbarium, and all are from the nineteenth century: “Evans Bay” in 1861, “Horokiwi Valley” in 1878, and “Wellington” in 1878.

As far as we can determine, the living populations of Asplenium lyallii closest to Wright Hill are at Titahi Bay (with a c.1986 specimen in WAIK, the herbarium at the University of Waikato), and Ruakokoputuna in the Wairarapa (with a 1998 specimen in WELT).   Asplenium lyallii is also recorded in a Tony Druce list for somewhere between Paekakariki and Te Kaukau Point.

We have not surveyed the Wright Hill site extensively, but observed about 20 plants of Asplenium lyallii in only a localised area.   It was with A. hookerianum, A. oblongifolium, and Polystichum neozelandicum, in hillside forest of macrocarpa over Melicytus ramiflorus, Coprosma grandifolia, and Macropiper excelsum.

Asplenium lyallii exhibits quite a range of morphological variation, especially in frond dissection.   It looks a bit like a hybrid might between Asplenium hookerianum and A. oblongifolium (or A. obtusatum), and it could be that A. lyallii is an allopolyploid species derived from such a combination.   Asplenium lyallii is endemic to New Zealand, and abundant in some parts of the country (Figure 3).   It is usually found on limestone, but not always as at Wright Hill.   It also usually has many scales on the upper surfaces of its fronds, but these are lacking in some populations, such as Wright Hill.

We would be grateful to anyone who can alert us to additional populations of Asplenium lyallii in the Wellington region.   We would like to thank John Sawyer, Colin Ogle, Chris Horne, Pat Enright, David Glenny, Peter de Lange, and Pat Brownsey for discussions and information.

Leon Perrie & Lara Shepherd Te Papa, P.O. Box 467, Wellington leonp@tepapa.govt.nz 04 381 7261

Figure 1.   A frond of Asplenium lyallii from Wright Hill, Karori, Wellington.   The frond measures c.28 cm long.	Figure 2.   Asplenium lyallii from Wright Hill, Karori, Wellington	Figure 3.   Distribution of specimens of Asplenium lyallii held by WELT.   There are also collections from the Chatham Islands.