The Identity of Jatropha pungens (Euphorbiaceae) and Its Consequences

Abstract

There does not appear to be any direct indication of the exact identity of Jatropha pungens Forssk. as no possible type material can be located and no locality is given in the protologue. The description given, by mentioning spikes of male flowers, stinging hairs like Urtica and female 'corolla' of 5-6 pinnatifid hirsute 'petals', confirms beyond all reasonable doubt that the plant is a Tragia but it is not detailed enough to be sure of the specific identity within what is a difficult genus. Vahl added some information to the original description, mentioning that the plant was a climber and that the leaves were acuminate so it does seem that there was material available which was subsequently mislaid. However, study of herbarium material from the Yemen coupled with field observations suggests that there is only a single common rather variable species of Tragia within the area covered by Forsskaal, and thus there seems to be very little doubt that Forsskaal's plant must have been what is now mostly called Tragia arabica (Muell. Arg.) Prain. A second species has been described from the same general area-T. moammarensis Baill., mostly differentiated by its erect habit but there seems to be a continual transition between virgately erect plants of open habitats and twining plants from denser vegetation. Other features of foliage or of the female sepals seem equally variable and of little taxonomic significance. It seems to us that the most satisfactory way of clarifying the situation is to neotypify T. pungens with the type of T. arabica as follows: