Olmeca, a new genus of Mexican bamboos with fleshy fruits

Olmeca, a new bamboo genus of two species is described from southern Mexico. It is unique among New World bamboos in its production of fruits that are large and fleshy, in contrast to the smaller, dry type-caryopsis or achene-that characterizes the other genera. The fleshy fruit is found in few other bamboos, among them Dinochloa, Melocanna, and Ochlandra. These Asiatic genera are not all closely related to each other nor to the new American genus, but do share a similar type of habitat: the tropical lowland rain forest, where ample water is available throughout the year. Besides the rare type of fruit found in Olmeca, the rhizomes of this genus develop necks up to 8 m or more long, an uncommon feature among any world bamboo of the sympodial type. The solitary culms of Olmeca grow widely spaced from one another because of these elongated, intervening necks. One species. 0. recta, is known only from the mountain range of Los Tuxtlas, in Veracruz, where it grows on acidic soils derived from basalt; the other, 0. reflexa, occurs on calcareous soils and has a wider range that encompasses parts of Veracruz, Oaxaca, and Chiapas. THE RICH MEXICAN RAIN FORESTS that clothe the low slopes of Los Tuxtlas mountains around Sontecomapan in eastern Veracruz yielded a most unusual flowering bamboo to the renowned palm specialist, Harold E. Moore, Jr., on his trip to that region in 1952. During the ensuing decades, the specimen that he collected remained unidentified and could not be matched with any known genus by the late bamboo specialist, F. A. McClure. The collection consisted of leafy branches that terminated in inflorescences, but lacked many of the vegetative structures that are necessary for the proper placement of a bamboo. At my request, Helen Kennedy, on a trip to the same region in 1976, made a collection of these structures, and the sample of a culm leaf that she brought back confirmed my suspicion that this particular "tree grass" was indeed different from any known. Unfortunately the structure was old and incomplete, but nevertheless added new dimensions to the concept of this mysterious bamboo that was now emerging. I Received for publication 8 September 1980; revision accepted 16 October 1980. I am indebted to Dr. Stephen D. Koch of the Colegio de Postgraduados, Chapingo, Mexico, for planning the itinerary of ajoint field trip to southern Mexico in October 1977 that brought us to the localities of Olmeca cited in this paper. I also wish to thank Biol. Mario Vazquez Torres of the Universidad de Veracruz (Xalapa), who provided material of the new genus, information on its ecology, and help in the field. Mr. Alasdair Burman, of Sao Paulo, prepared the Latin descriptions of the new taxa, and the illustrations were the handiwork of Ms. Alice R. Tangerini (ART), to whom I am always grateful for her superb renditions of bamboos. Later in the same year, I received from Biol. Mario Vazquez Torres, of the Universidad de Veracruz, some fragmentary samples of bamboos from the tropical rain forests of southern Veracruz where he was working on aspects of population biology in bamboo communities. Some of the collections represented the same species that Moore and Kennedy had collected on separate occasions, but again the material was too fragmentary and incomplete for a full understanding of it. About this time came a collection of bamboos from Chiapas made by Dennis Breedlove. When I examined these, it was apparent that the flowering branches of one of the bamboo gatherings had an inflorescence similar to that of the Veracruz material, but almost certainly represented a different species. Again, only flowering branches were available, the specimens in this case lacking the vegetative parts necessary to form a complete picture of the plant. By now it was quite clear that the tropical forests of southeastern Mexico harbored what might be a new bamboo genus, and only a personal visit to the region would satisfy my curiosity. With my colleague, Stephen Koch, of Chapingo, Mexico, I made a journey to Chiapas, Oaxaca, and Veracruz during SeptemberOctober of 1977 and collected full material of two species of the genus, each adapted to different soils and habitats. Particularly intriguing was the statement by Moore on the label of his specimen that the bamboo produced fruits that were "green, globose to 1 inch in diameter." When McClure