Cyperaceae of tropical West Africa

With more than 5,500 species worldwide the Cyperaceae family is one of the most speciose families of the
monocots, in number only preceded by Orchidaceae and Poaceae. The species are very widely distributed
across the globe and occur on all continents except Antarctica. They can be found in cool, wet Alpine habitats
as well as in hot, tropical and desert-like situations, ranging from sea level to high altitudes. Species
are morphologically very diverse, varying from diminutive annuals to dracaenoid shrubs or even lianas. The
family is well studied, and modern techniques have been applied to this, but many species and genera are
still relatively poorly understood, doubtlessly at least in part due to the fact that floral structures are often
complex and not easily interpreted.
The African continent is an important diversity center for the family; over 1,000 species are present there,
many of them endemic. Species in the East and South are very well studied and the current knowledge is
reflected in contemporary floras covering these areas. On the contrary, species present in tropical West Africa
(although also a hotspot for the Cyperaceae family) are much less well known and the knowledge is rather
fragmented. The most recent account that refers to the entire region dates back to the early 1970’s when the
family was treated in the Flora of West Tropical Africa (Hutchinson & Dalziel 1972), i.e. about half a century
ago. In the intervening years useful local flora accounts were published (e.g. Lowe & Stanfield 1974, Berhaut
1988, Lisowski 2009), numerous new taxa have been described from the area and the known distribution of
others was updated. Knowledge on several genera or complex species groups has considerably increased.
In recent years, one of us (Attila Mesterházy), was able to conduct field studies in many countries in tropical
West Africa. On these occasions he discovered species that turned out to be new to science. In addition, he
was also able to extensively document poorly known taxa on the basis of herbarium collections and field
photographs. Gradually the idea matured to gather together this newly acquired knowledge and make it
available to other researchers studying the West African flora. The results of years of study by the authors
are presented here.
This book aims at improving the knowledge of tropical West African Cyperaceae. This means that all information
at hand is included in it. As a rule, a full-page color plate illustrates each of 321 taxa comprising the
study (exceptionally two taxa are depicted in a single plate). Illustrations include a representative herbarium
specimen and all details useful for an accurate identification (inflorescences, spikelets, glumes, nutlets etc.).
If available, photographs are also included, either of an inflorescence or of the species in its habitat. Each
taxon is briefly described, mostly based on the authors’ personal observations and measurements. Further
details on its distribution (in the study area as well as beyond) and ecology are also presented. For each taxon,
synonyms are provided if deemed useful. Information on type material is of the utmost importance for
taxonomic studies and much time was therefore spent on searching for types; protologues of all taxa were
checked and online herbaria inspected. However, for many taxa lecto- or neotypes still need to be designated.
Information useful for a future type designation is presented but the designation of types was beyond
the scope of this book.
Identification keys for all genera and infrageneric taxa are included, as well as some novel Quick Guides.
Based on experience in the field as well as in the herbarium, additional notes on species are provided. These
include information on the identification (useful characters, separation from morphologically similar taxa
etc.) and/or refer to taxonomic or nomenclatural issues.

The area covered by this book is defined as tropical West Africa but this requires some clarification. Following
Brummitt’s World Geographical Scheme for Recording Plant Distributions (Brummitt 2001), only that part of
tropical West Africa south of the 18° N latitude is taken into account. The entirety of the following countries
is covered: Benin, Burkina Faso, Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Nigeria, Senegal,
Sierra Leone and Togo. Mali, Mauritania and Niger are located in part north of the 18° N latitude and thus
only partly treated. Species from these three countries that exclusively occur in the northern part are not
treated in this book. For example, Carex enokii occurs in Mauritania but only north of the 18° N latitude; it is
thus not included.
As a result of molecular phylogenetic studies, knowledge on Cyperaceae has markedly increased. These studies
have re-circumscribed the boundaries of certain genera. As far as Cyperus is concerned, it was demonstrated
that morphologically similar genera like Kyllinga, Mariscus and Pycreus are better included in it. This
also applies to some other genera that are less obviously related to Cyperus e.g. Ascolepis, Lipocarpha or
Oxycaryum. Analogously, Nemum was shown to be part of a broadly circumscribed genus Bulbostylis etc.
Although the authors endorse these new insights, a more conservative approach was used for this book,
not only because most of the taxa involved are better known under their older, ‘traditional’ names, but also
because in most herbaria (and a fortiori in the African ones) taxa are still arranged the traditional way. However,
for each of the taxa concerned, the alternative name in the ‘new’ genera is also displayed above the
illustrations, immediately following the name applied by the authors. For convenience, a table of comparison
between ‘old’ and ‘new’ names is presented, as an addendum, at the end of this book.
A new variety of Bulbostylis coleotricha is here described (var. hirsuta) whereas an undescribed species of
Mapania from Liberia awaits additional research. The new combination Cyperus tenax subsp. monroviensis is
proposed and several species were synonymized with existing ones, e.g. Pycreus felicis, Fimbristylis nigritana
and Eleocharis deightonii (syn. nov.).
It is hoped that this book will encourage researchers in tropical West Africa to renew their attention to this
extremely interesting family. In addition, since many of the taxa included also occur in other tropical and
subtropical areas across the world, it will doubtlessly be useful to anyone interested in Cyperaceae.