Adenia is a genus of flowering plants in the passionflower family Passifloraceae. It is distributed in the Old World tropics and subtropics. The centers of diversity are in Madagascar, eastern and western tropical Africa, and Southeast Asia. The genus name Adenia comes from "aden", reported as the Arabic name for the plant by Peter Forsskål,  the author of the genus.

Description 
All Adenia are perennial plants, but there are many different forms, including herbs, vines, shrubs, and trees. Many are succulents and some are pachycauls. Some have fibrous root systems and some have tubers. Adenia can be found in a wide variety of habitat types, from dry African deserts to wet Southeast Asian rainforests. There are about 100 species in the genus.

Adenia have alternately arranged leaves borne on petioles. There are two glands located near the attachment of the leaf blade to the petiole. Most species are dioecious. Inflorescences of a few to many flowers occur in the leaf axils. There is a stipe below the flower. The calyx has five lobes and the five petals are usually smaller than the sepals and may be whitish or greenish. The male flower has five stamens. In the female flower these are reduced to staminodes. There are three styles tipped with stigmas that may be long-hairy to very woolly. The fruit is a red capsule. Each black seed has a fleshy aril.

Adenia species can be difficult to identify and distinguish as individuals of a species can be variable. One plant can have leaves of varying shapes and sizes, and young and old specimens can have different leaf types. Some taxa are poorly represented in herbarium collections, leaving few examples to compare with new specimens. Records of some taxa lack descriptions of both (i.e. male and female) flower types. Many species only flower for a few weeks, and during this time they may also lose their leaves. Succulent plants can be difficult to properly collect and preserve.

Uses 
Several species are used in traditional African medicine. Various parts of A. cissampeloides are used to treat many conditions, including gastrointestinal problems, inflammation, pain, fever, malaria, leprosy, scabies, cholera, anemia, bronchitis, sexually transmitted diseases, menorrhagia, and mental illness. It is used both as an abortifacient and to prevent miscarriage. A. dinklagei leaves are ingested to treat palpitations. The leaves of A. tricostata are used to treat fever. The leaves or leaf sap of A. bequaertii are taken to treat headache, mental illness, and possession. A. lobata stems are applied to sites of Guinea worm infection during extraction of the worm. It is also used as an enema and an aphrodisiac.

A. cissampeloides is used as a fish poison and arrow poison. The red-colored sap is used as a cosmetic. The stems can be made into rope. The crushed twigs or smoke from burning roots can be used to calm honeybees during honey harvest.

The leaves of A. cissampeloides are eaten as a vegetable in parts of Africa.

A. digitata is cultivated as an ornamental plant for its very large, distinctive aboveground tuber.

Toxicity 
Many Adenia are poisonous. They contain lectins such as lanceolin, stenodactylin, and volkensin, which are toxic to cells. They cause apoptosis, hemagglutination, inhibition of protein synthesis, and depurination of ribosomes and DNA. Mouse experiments with small doses of lanceolin and stenodactylin, from A. lanceolata and A. stenodactyla, respectively, revealed that they are "amongst the most potent toxins of plant origin".

The fruit of A. digitata has been used in Africa to commit homicide and suicide.

Species 

The following is a list of all 106 species in this genus that are accepted by Plants of the World Online 

 Adenia aculeata 
 Adenia acuta 
 Adenia adenifera 
 Adenia angulosa 
 Adenia antongilliana 
 Adenia ballyi 
 Adenia banaensis 
 Adenia barthelatii 
 Adenia bequaertii 
 Adenia boivinii 
 Adenia cardiophylla 
 Adenia cissampeloides 
 Adenia cladosepala 
 Adenia cordifolia 
 Adenia crassa 
 Adenia cynanchifolia 
 Adenia densiflora 
 Adenia digitata 
 Adenia dinklagei 
 Adenia dolichosiphon 
 Adenia ecirrosa 
 Adenia elegans 
 Adenia ellenbeckii 
 Adenia epigea 
 Adenia erecta 
 Adenia fasciculata 
 Adenia fernandesiana 
 Adenia firingalavensis 
 Adenia fruticosa 
 Adenia gedoensis 
 Adenia glauca 
 Adenia globosa 
 Adenia goetzei 
 Adenia gracilis 
 Adenia guineensis 
 Adenia gummifera 
 Adenia hastata 
 Adenia heterophylla 
 Adenia hondala 
 Adenia huillensis 
 Adenia inermis 
 Adenia isaloensis 
 Adenia karibaensis 
 Adenia keramanthus 
 Adenia kigogoensis 
 Adenia kinabaluensis 
 Adenia kirkii 
 Adenia lanceolata 
 Adenia lapiazicola 
 Adenia latipetala 
 Adenia letouzeyi 
 Adenia lewallei 
 Adenia lindiensis 
 Adenia litoralis 
 Adenia lobata 
 Adenia longistipulata 
 Adenia macrophylla 
 Adenia malangeana 
 Adenia mannii 
 Adenia mcdadiana 
 Adenia metamorpha 
 Adenia metriosiphon 
 Adenia monadelpha 
 Adenia mossambicensis 
 Adenia natalensis 
 Adenia olaboensis 
 Adenia ovata 
 Adenia pachyphylla 
 Adenia panduriformis 
 Adenia pechuelii 
 Adenia peltata 
 Adenia penangiana 
 Adenia perrieri 
 Adenia pierrei 
 Adenia pinnatisecta 
 Adenia poggei 
 Adenia poilanei 
 Adenia pulchra 
 Adenia pyromorpha 
 Adenia racemosa 
 Adenia refracta 
 Adenia repanda 
 Adenia reticulata 
 Adenia rumicifolia 
 Adenia schliebenii 
 Adenia schweinfurthii 
 Adenia sphaerocarpa 
 Adenia spinosa 
 Adenia staudtii 
 Adenia stenodactyla 
 Adenia stolzii 
 Adenia stricta 
 Adenia stylosa 
 Adenia subsessilifolia 
 Adenia tisserantii 
 Adenia tricostata 
 Adenia trilobata 
 Adenia trisecta 
 Adenia tuberifera 
 Adenia venenata 
 Adenia viridiflora 
 Adenia volkensii 
 Adenia welwitschii 
 Adenia wightiana 
 Adenia wilmsii 
 Adenia zambesiensis

References

Further reading 

 
 

 
Malpighiales genera
Dioecious plants