Broomrapes of the world

Broomrapes (family Orobanchaceae) are among the most curiously beautiful and least understood plants. These plants are parasitic on, and attach to the roots of, other plants to extract their nutrients. The family has a wide global distribution, and broomrapes occur in diverse habitats on a wide range of host plants. Many broomrapes are entirely devoid of functional leaves, roots and chlorophyll (holoparasitic) and possess a remarkable, rather ghostly appearance – rising out of the ground, seemingly from nowhere. In this book we adopt a broad definition of a broomrape (a name traditionally used for the Old- World genus Orobanche) and cover all holoparasitic genera in the family. The name broomrape derives from broom and the Latin rapum for ‘turnip’ – in other words, a turnip of broom. This refers to the swollen stem base of O. rapum-genistae attached to the roots of its host (typically broom) – and now used to describe all species in the Orobanche genus and in its broadest sense, other genera in the family, for example the Indian broomrapes (genus Aeginetia), and clustered broomrapes and desert broomrapes (genus Aphyllon). In recent years, broomrapes have sparked interest among plant enthusiasts in a similar way to orchids. Like orchids, broomrapes are renowned for being taxonomically challenging. Plants that appear distinct in the field are prone to becoming blackish-brown and featureless when pressed, which has led to the incorrect determination of herbarium specimens in many of the genera. Confusion has been compounded by intra-specific variation in some species (for example in the genera Orobanche and Cistanche), confusing synonymies, incorrectly cited nomenclature, and species with poor type specimens and descriptions. Nevertheless, identification of broomrapes in the field can be straightforward with careful examination. This book seeks to give clear and detailed accounts of a range of species from all the main genera around the world, so that they may be identified reliably. Photographs and illustrations have been selected to capture as much of the diversity across genera as possible in this book. Many of the photographs were kindly provided by other botanists and enthusiasts so that the family could be well represented geographically. Ultimately this book seeks to promote awareness and dispel confusion about the broomrapes – a family of striking and fascinating botanical enigmas.