Sedge Research at Kew
Cyperaceae
Newsletter
What are sedges?
The sedges - Cyperaceae - form one of the larger and more diverse
plant families being actively researched at Kew, comprising c.4000-5000
species in 102-123 genera.
Sedges have a superficial resemblance to grasses. However they are not
closely related and differ in many characteristics, particularly in the
structure of the inflorescence.
Sedges have considerable economic and ecological importance. They are,
however, well-known for being difficult plants to identify and specialist
advice is often required.
Kew has a long-standing tradition of expertise in sedges and, with the
richness of its collections, is uniquely placed at the forefront of research
on and identification of this family.
Importance of sedges
- Agriculture A number of sedges are serious and persistent weeds
of agriculture, particularly in the tropics, where they are often associated
with rice cultivation. One species, Cyperus rotundus, has the dubious
reputation of being termed 'the world's worst weed'.
- Food Several species are used as human food plants, the most
notable of these being the edible tubers of Eleocharis dulcis (the
chinese water chestnut, an important crop in Asia) and Cyperus esculentus
(tiger nut or chufa). In many parts of the tropics, particularly Africa,
sedges also provide fodder for domestic animals.
- Fuel Some species, particularly papyrus (Cyperus papyrus),
are becoming increasingly important for providing fuel in the tropics.
- Horticulture Sedges are being increasingly valued as horticultural
subjects. Many species in cultivation show striking variegation of their
leaves while others are highly regarded for their unusual floral structure.
Many other species have potential horticultural uses.
- Other uses The economic importance of sedges stretches back
into antiquity with papyrus (Cyperus papyrus) being used for papermaking
and boat building in ancient Egypt. Today, sedges are used throughout the
tropics for basketry and mat weaving, and in parts of Africa and Asia they
are cultivated for such purposes. They are also used for thatching, fencing,
rope making, pot pourri and perfumery. Several species are recorded as
having medicinal properties while others have the potential for use in
erosion control and sand stabilization.
- Conservation Sedges occur within a wide spectrum of vegetation
types, ranging from the ground layer of tropical rainforest to temperate
blanket bog and arctic tundra. They are important, often dominant elements
of many wetland ecosystems, which today are severely threatened by the
human activity. Indeed, some species may be in danger of extinction. Sedges
are often highly sensitive to changes in nutrient status and their appearance
or disappearance from a given area may act an indicator of damage to an
ecosystem. They also provide food and shelter for wildlife. Therefore are
of prime importance in conservation.
Research programmes
Kew has maintained a long line of research on sedges going back over
100 years, and during this time an almost continuous succession of botanists
have worked on the family.
As a result the Kew Herbarium has a collection of c.100,000 Cyperaceae
specimens which is unrivalled elsewhere and continues to grow at some 2000
to 3000 specimens per year. The collection at Kew is particularly rich
in type material and many sedge species were first described by Kew botanists.
Historically, the collection is particularly strong in specimens from
Africa, India and Brazil, but there is a wide range of material from all
parts of the worldsedges are present. It is fair to say that nearly all
the sedge species known to science are represented by specimens in the
Herbarium. About two-thirds of the specimens sent to Kew require naming
and it is from this material that new species may be discovered.
In all sedge research at Kew, particular importance is being attached
to the structure of the fruits (variously termed nuts, nutlets or achenes).
Surveys of these using scanning electron microscopy are yielding many useful
characters. New techniques and sources of data, including DNA sequencing,
are continually being looked at in order to improve the classification
of sedges. Special emphasis is placed on cladistic and phenetic techniques
to analyse data.
Research activities are divided into three main areas:
- Monographic work is currently centred on the tribe Hypolytreae,
a group of eight genera which occur mainly in the herb layer of tropical
rainforest. Their inflorescence structure is unique in Cyperaceae but difficult
to interpret due to its reduced nature. A better understanding of the tribe
may hold important clues on the evolution of Cyperaceae. The genus Mapania
has been revised and work is proceeding on Hypolytrum. Attention
is also being given to Scirpus s.l. and Cyperus. These occur
worldwide and have considerable economic importance, but are rather poorly
known. The work aims to clarify the limits and relationships of several
sections within each genus and from this it is hoped to get a better understanding
of the genera as a whole.
- Floristic work currently covers East and Southern Africa, parts
of Brazil, Thailand and Indo-China and Malaysia, with Flora accounts or
checklists currently being prepared for these regions/countries.
- Economic Botany research includes the compilation of a database
of Cyperaceae with economic and ethnobotanical importance. Nearly 400 taxa
are now included, and a Checklist is being prepared.
Help and information on Sedges
- Herbarium Bona fide researchers may examine the herbarium collections
in person by prior arrangement. Specialist advice can be given on sedge
classification.
- Living collections A wide range of material covering a number
of genera is in cultivation. Plants of both horticultural and scientific
interest are represented and many are on display to the public.
- Economic botany The economic botany collections house a range
of products and artefacts derived from sedges. The Survey of Economic Plants
for Arid and Semi-Arid Lands (SEPASAL) details a number of sedges with
actual and potential economic uses.
- Seed Bank collections The seed bank has range of material in
cold storage, and new accessions are continually being added. Material
is available to research institutions on request.
- Library The Library has the most comprehensive collection of
books, papers and illustrations on sedges anywhere in the world, including
some of the earliest literature published on the family.
- Cyperaceae
Newsletter published by Kew and Gent University (Belgium) contains
news of current research and short papers on sedges together with comprehensive
lists of new names and bibliographies of newly published literature.
For further information please contact
The Curator
of Cyperaceae
Herbarium, Royal Botanic Gardens, Kew, Richmond, Surrey, TW9 3AE UK
Tel: +44 181 332 5000
Fax: +44 181 332 5278