Not an ordinary passion fruit
You would think that spending years of almost weekly visits to the local Hang Dong fruit and vegetable market in Chiang Mai would eventually give you the confidence of naming almost any plant for sale there. Recently I went there with visiting Japanese guests and to my surprise there was a peculiar plant for sale I could not identify:
It was a glabrous vine with tendrils. The fleshy flowers had only male organs situated deep inside. In the market the flowering clusters were wrapped in Dipterocarpus tuberculatus leaves, indicating somebody had picked them in the wild rather than inside a garden. For its identification I had to contact members of my botanical network within Southeast Asia and most of us were puzzled until Dr Santi Watthana at the Queen Sirikit Botanic Garden suggested the genus Adenia of the passionfruit family (Passifloraceae). Indeed, a quick check with Flora of China and Flora of Thailand (10:2) confirmed his amazing field experience and it turns out to be a male specimen of Adenia heterophylla.
This species has separate male and female flowers (dioecious), and is characterized by glabrous leaves with concave auricles (the funny structures on the leaf stalk), tendrils and balloon-like flowers. There is no latex nor any conspicuous fragrance. This climber can reach 30 meters in length.
The genus Adenia was coined by the Swedish botanist Peter Forsskål in Flora Aegyptiaco-Arabica (page 77) published in 1775. It is named after the city Aden, an important trading port situated in today’s Yemen where Forsskål died in 1763. Most of the ca 100 Adenia species are found in Africa and Arabia, and many have succulent stems or tubers like those in the desert rose Adenium (Apocynaceae). The species name ‘heterophylla’ alludes to the fact the leaf shape vary significantly, sometimes lobed, but is always equipped with the funny auricles which is a common feature of the passionfruit family.
There are four species of native bisexual or ‘normal’ passionfruits (Passiflora) in Thailand. There are six species of the unisexual and less known genus Adenia in Thailand. This species A. heterophylla is different from the similar A. viridiflora based on e.g. the length of the flowering stipe. It is found in the lowlands from southern China to most of Southeast Asia and western Australia.
Interestingly, the plant is reportedly poisonous, only used for hunting, so I am very curious about the intentions of the vendor at the Hang Dong market. We urge our readers in Southeast Asia to ask for it in markets and to ask about its use.
According to Tem Smitinand local names in northern Thailand might be ‘nang nun’, ‘nun’ or ‘phak sap’.
Text & Photo: Eric Danell & Ketsanee Seehamongkol, Dokmai Garden