ARISTOLOCHIA GRANDIFLORA SW. (ARISTOLOCHIACEAE): DEVELOPMENT AND MORPHOLOGY OF THE WORLD'S LONGEST FLOWER

Abstract

Aristolochia grandiflora Sw. has the longest flowers on Earth. The distribution of this species includes Mexico, Central America, Cuba, Jamaica, Colombia, Trinidad, and Ecuador; some collections from St. Thomas, Guadeloupe, and Martinique could correspond to cultivated and naturalized populations. Although this species is well known in cultivation because of its bizarre floral morphology, it is less known in the wild. Besides the large size of its flowers, the morphology of the perianth is different from that found in the other neotropical species of subgenus Aristolochia; these differences affect both the lateral zygomorphy (i.e. an unequal growth along the floral tube) and the frontal (i.e. an unequal growth of the limb of the perianth) symmetry; furthermore, the flower of A. grandiflora develops two inner structures, the syrinx, and the annulus. We describe the floral development, especially that of the perianth, along with the record that is, without doubts, the longest known flower in the wild. Finally, we discuss the phylogenetic relationships of the species.