Linear sequences for seed plants

Why classify?

Classification systems are needed to organise our knowledge of the natural world and aid communication. Biologists use classifications that reflect the evolutionary relationships between organisms, and base them on phylogenetic trees that are often branched. Specimen collections need to be arranged in a linear order (e.g. along shelves or in cupboards) so the branching nature of phylogenetic trees creates a problem for curators who wish to arrange collections in a manner that reflects the patterns of evolution rather than, for example, alphabetical order. Curators need an agreed ‘linear sequence’ to order their collections in a way that represents the phylogenetic classification.

Various linear sequences of plant families have been proposed, and a range of systems are in use. However, our understanding of the relationships between families has changed in recent years and many systems no longer represent this in the best way. Botanists at Kew have been collaborating with colleagues from Cornell University, the Finnish Museum of Natural History and the Royal Botanic Garden Edinburgh to construct new linear sequences for seed plants based on the current understanding of relationships gained through molecular phylogenetics.

Published recommendations

Recommended linear sequences have been published in a special, open-access issue of the journal Phytotaxa, edited by Maarten Christenhusz (Finnish Museum of Natural History), Mark Chase and Mike Fay (Kew). One paper updates the linear sequence for flowering plants originally constructed by Haston et al. to accompany the Angiosperm Phylogeny Group III (APG III) classification in 2009. The paper also provides synonyms of the orders and families recognised by the APG III classification. A second paper gives a new classification and linear sequence for gymnosperms. In a third paper, other scientific colleagues provide a linear sequence to lycophytes and ferns.

The Herbarium at Kew will be re-organised to reflect the APG III classification. With an estimated 7 million specimens to move, this will be a gargantuan logistical operation that is expected to take two to three years!.

Article references:

Christenhusz, M. J. M., Chase, M. W. & Fay, M. F. (eds) (2011). Linear sequence, classification, synonymy, and bibliography of vascular plants: Lycophytes, ferns, gymnosperms and angiosperms. Phytotaxa 19: 1–134.

Haston, E., Richardson, J. E., Stevens, P. F., Chase, M. W. & Harris, D. J. (2009). The Linear Angiosperm Phylogeny Group (LAPG) III: a linear sequence of the families in APG III. Botanical Journal of the Linnean Society 161: 128–131.

More on this story

Phytotaxa 19 (open access)

Linear Angiosperm Phylogeny Group III (Haston et al., 2009)

Background

Angiosperm Phylogeny Group website

Kew Science Project – Angiosperm Phylogeny Group III

Related stories

Kew News – Establishing a common classification with APG III

Kew News - As easy as APG III - Scientists revise the system of classifying flowering plants

Kew Scientist 36 – APG III

Help Kew break new ground and inspire new generations

By making a donation to Kew today you can help our scientists to find out more about the fascinating world of plants, break new ground and inspire generations of young people to get to know plants better.

Our scientific programmes are focused on understanding plants and conserving the world's plant life and habitats at risk. Plants are essential to life on earth. In a world where the sustainability of the planet’s rich biodiversity is becoming less certain, Kew’s science work is ever more critical. Find out how your donation can make a difference.

Give now and support Kew’s vital plant science work

Browse Kew news

• In the Gardens
• Science and conservation
• How you are helping
• Specialist science
• Kew blogs
• All Kew news