Gearum (Araceae) Rediscovered

Abstract

Gearum brasiliense N. E. Brown, has hitherto been known only from a single inflorescence, collected in October 1828 by W. J. Burchell. Knowledge of the genus has thus been incomplete, particularly due to lack of leaf material. Burchell's specimen is substantially damaged by insect attack and very fragile. Despite this handicap, the present study has shown that Brown's original description was remarkably accurate. The precise location of Burchell's collection remained unclear until now. Burchell's field notebook in the Kew Archive (K) gives the following details:"between Sap6 and Santa Brizida (Serra Sta. Brizida) on the plains in low lying places that are often inundated (River from the ferry)". The locality names Sape and Santa Brizida, given by Burchell, could not be traced for this region in the gazeteers examined. However, the adjacent localities given in Burchell's notebook suggest that the plant must have been collected somewhere in the valley of the Rio da Palma, between Conceig-io do Norte (also called Conceigao do Tocantins) and Arraias, in the modern state of Tocantins (previously the northern part of Goias). There is today a village called Sapo in this area which could be the same as Burchell's "Sap'" and Burchell himself mentions the Rio da Palma, a tributary of the Rio Parani, which is in turn a tributary of the Rio Tocantins. The coordinates given by Smith & Smith (1967) are approximately 75 km (air distance) too far east. Not long after collecting the type of G. brasiliense, Burchell made another Araceae collection further north along the Rio Tocantins, this time of leaves only (Burchell 8598 (K!)). In the absence of a second collection of Gearum, there has always been doubt as to whether these pedatisect leaves are of the same species. Their identity remains unsolved, but they must be of a species of Xanthosoma sect. Acontias. The only other possibility, suggested by Brown himself, is that they are of a species of Chlorospatha. This genus, however, has never been recorded from Brazil. A second, more complete collection of Gearum brasiliense has been made after 150 years by Alfeu de Araujo Dias, a botanist who worked for the Brazilian national resources survey, Projeto RADAMBRASIL. Specimens seen at the