Very big books about very small plants

Wednesday 19 Jun 2019

Haplomitrium ovalifolium

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.”

FAQ:

What are liverworts?

Liverworts, together with mosses and hornworts, are commonly referred to as bryophytes, the second largest group of land plants after flowering plants.

Why are they important?

Liverworts, along with mosses, have a significant role in contributing to nutrient cycles, providing seed-beds for larger plants, and forming microhabitats for insects and an entire array of microorganisms.

Liverworts and mosses are very effective rainfall interceptors, and help to reduce the impact of heavy rainfall, including adding to hill stability and helping to prevent soil erosion.

Chemicals produced by liverworts are of interest to medical science for their important biological activities, including anti-bacterial and anti-microbial properties. These chemical compounds are found in the oilbodies, a specialised cellular organelle unique to liverworts.

Why are liverworts particularly valuable for New Zealand?

Unlike forests elsewhere in the world, New Zealand’s evergreen forests don’t have much herbaceous ground flora. Instead we have a very rich bryophyte ground flora. In the north and in the tropics, ground bryophytes are often smothered by leaf litter. Our bryophyte flora specialises in growing through the litter layer, so we have more large dendroid mosses and liverworts than any other flora in the world.

How long has the work on this flora taken?

New Zealand has been waiting for a flora of liverworts and hornworts for a long time. Prof Schuster from the University of Massachusetts started work on the flora half a century ago, and John Engel, who used to be curator of bryophytes at the Field Museum, Chicago, joined him in this endeavour. John and Manaaki Whenua’s David Glenny have together completed the first three of four volumes of the flora.

Volume 1 was launched in 2008, and volumes 2 and 3 will launch on 19 June 2019, with the fourth volume underway. When completed, this will be the first flora for these groups of plants since Joseph Hooker’s 1864-1867 Handbook of the New Zealand flora.