Very big books about very small plants

This week sees the publication by Missouri Botanical Garden Press of the second and third volumes of a landmark collection of books known as a flora, representing all we know about a small but very significant aspect of New Zealand’s plant biodiversity – liverworts and hornworts.

For Dr David Glenny, an expert in plant research and identification at Manaaki Whenua Landcare Research, the liverwort flora is the result of around 30 years’ work, co-researched and written with John Engel of the Field Museum in Chicago, who is the world authority on this group of plants in the southern hemisphere.

During his work on the flora, David collected more than 14 000 specimens and made microscope observations to confirm their identities. Currently, 653 species of liverworts and hornworts are known from New Zealand, and their national and international importance is only recently beginning to be understood.

In New Zealand we have the richest liverwort flora in the world for the size of our country, and it’s quite different from other places. As David explains: “People often think that the larger the plant the more important it is, but our small, unassuming liverworts are essential parts of our natural ecosystems. For instance, they help to intercept rainfall in native forests, decreasing rainfall run-off and helping to stabilise our soils. The chemical make-up of some liverworts may have important biological activities, for example anti-bacterial or anti-microbial properties, which merit further research. Liverworts are also believed to be the earliest plants to have colonised land from the sea, and there’s currently a lot of international scientific interest in finding out how that happened.”

Writing a flora is not like writing any other book. It’s an incredibly painstaking and thorough process of scientific observation and measurement, which takes dedication, patience, and vast knowledge.

When complete, a flora is equivalent to a dictionary for a language, in which the definitions are replaced by descriptions and illustrations. The flora has identification keys for each species, and gives detailed distribution and habitat notes.

The liverwort flora is not intended to sit on shelves or coffee tables. It will be a valuable and much-used tool for biodiversity and biosecurity managers, biochemists and horticulturists – “everyone who works with plants, reads about plants or thinks about plants,” says David. “It will help us to manage threatened plants and will underpin important conservation decisions.”

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