Gardeners' Chronicle (3rd series) 31: 375 (June 7, 1902)


In a recent issue of the Journal de l'Agriculture Tropicale, attention is called to a paper of M. LEMARIÉ on the tubers of Plectranthus as a vegetable. These plants are Labiates, closely allied to the already known Stachys affinis; they produce tubers that can be used similarly. MM. PAILLIEUX and BOIS, who introduced this plant (and also the Stachys), have failed to acclimatise it in France, owing to insufficient heat; but M. MAXIME CORNU introduced it successfully into Madagascar, the Congo, Gaboon, the Soudan, and Indo-China, whence excellent reports of it have been obtained, testifying to its value in countries where Potatos do not thrive. The tubers of Plectranthus even exceed in amount of starch and farinaceous properties those usually cultivated in the colonies, and those of Stachys tuberifera (affinis). There are several species of Plectranthus, and they are not easily identified; most of them are natives of tropical Africa, India, and Malaya. At Hanoi in 1898 four small tubers the size of a nut were planted in the botanic garden, and from these M. LEMARIÉ raised gradually increasing crops of tubers, that in January, 1900, were as large each as a hen's egg, and in their entire weight attained to 208 kilos., or about twice that number of English pounds. At the same time, very similar tubers were distributed which, when cultivated, showed such differences that they were determined to be distinct species. In the flowers the tint of blue and the position of the stamens with regard to the pistil varied. M. CORNU gave the first plant here mentioned the name of Plectranthus Coppini. Dr. HECKEL prefers the name Coleus Coppini. MM. PAILLEUX and BOIS received from Réunion tubers of yet another species, known in the Transvaal; these on trial proved to be those of P. tuberosus (Coleus tuberosus). Now it is identified with P. ternatus. In 1887 the late M. PIERRE, Director of the Libreville Botanical Garden, introduced the new vegetable into the Congo, where it was highly valued. The Potager d'un Curieux mentions yet a fourth species, Coleus tuberosus, cultivated in Ethiopia; this has since been identified with C. edulis. Various other species have also been reported from tropical districts, but some of these are doubtless identical with those already mentioned, and when the vegetable receives further attention, the list of distinct species will be diminished. The properties of the varieties are practically alike. In parts of Tonkin the Plectranthus tubers will fill an otherwise unfertile period between May and October, leaving the ground free for other crops the rest of the year. This remark applies to other countries also. M. LEMARIÉ judiciously remarks that before drawing hasty conclusions or planting the new tubers on too large a scale, attention should be paid to developing those that are largest of size, and in hastening on also the period of growth as much as possible. The species mentioned as producing edible tubers are Coleus tuberosus (Malaya), Coleus barbatus (East tropical Africa, India), Plectranthus esculentus (Natal), Plectranthus floribundus (tropical Africa).