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In Book Takes, authors share three things that readers will gain from their books as well as giving an insight into what they learnt during the researching and writing. This weekend, Leon Perrie talks about the Identification Guide to the Ferns and Lycophytes of Aotearoa New Zealand.
Ferns are one of New Zealand’s natural icons, with the silver fern emblem recognisable around the world. Te Papa botanists Patrick Brownsey and Leon Perrie have some six decades of combined experience studying the diversity and classification of New Zealand’s ferns.
Between 2012 and 2022, they completed the Ferns and Lycophytes series for the Flora of New Zealand.
“We wanted to complement that definitive but technical account with a guide accessible to beginners,” says Perrie. “When I’m learning a new group of plants, I like to have lots of pictures alongside a few, easily understood words to guide me as to what features I should be looking at – that’s the book we’ve made for ferns in Aotearoa.”
Unfortunately, Brownsey died during the preparation of the book, but it rests on the legacy he left. Here’s what Perrie thinks readers will learn from the Identification Guide.
The numbers of ferns in New Zealand may be a surprise
New Zealand is home to 204 indigenous species of ferns and lycophytes (an allied group of plants). That’s about 8% of the indigenous vascular flora, and it makes ferns a good group of plants to learn – small enough to be manageable, but big enough to be challenging and rewarding. The book covers 201 of the ferns and lycophytes most encountered in New Zealand, both native and exotic.
That might seem a lot of ferns, but smaller landmasses like Fiji and Solomon Islands have even more indigenous species. New Zealand’s cultural connection with ferns comes much more from their prominence in our environments.
Recognising ferns relies on a few key characteristics
Probably most useful is the shape and position of the reproductive structures. Ferns have no flowers or seeds, but reproduce via spores. They make their spores in structures on the underside or at the margin of their fronds. Whether the spore-making capsules are arranged in lines or circles and at the frond margin or away from the margin provides a big clue as to which family or genus group a particular fern belongs to.
Other characteristics emphasised in the book are the extent of division or branching of a frond; whether a frond is scaly, hairy, or naked; whether the frond margins are toothed or smooth; and whether the fronds are spread along a creeping stem or more or less tufted from the same point.
Not all ferns in New Zealand are indigenous
Some 60 species of exotic ferns have been introduced to New Zealand and become weedy here. Some are ecologically problematic. So-called Male fern invades indigenous forest; Polypody outcompetes smaller plants on the Port Hills and is spreading northward. Horsetail clogs streamsides and other damp ground. The introduced Azolla fern has pushed out the native species from most of Northland and Auckland.
Being able to distinguish weedy species from their indigenous kin is critical for their management and caring for our environment.
An insight I gained while writing the book
Underpinning the book are the photos I had accumulated through some 20 years of study. But I still had to make special trips to get particular photos for some species, and for pillwort, I had no photos at all. Pillwort is a tiny, aquatic fern with thread-like fronds that lives on the bottom of lakes. I went snorkelling in a couple of South Island lakes to find it. It was very cold, but I got the photos, and had my eyes opened to the underwater delights of New Zealand’s freshwater plants.
Guide to the Ferns and Lycophytes of Aotearoa New Zealand by Leon Perrie and Patrick Brownsey (Te Papa Press, $50) is out now.
