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Anatomia, ultraestrutura e química das glândulas foliares de Passiflora L.(Passifloraceae)

Doctoral dissertation, Universidade de São Paulo

Lemos, R. C. C. D.


Doctoral dissertation, Universidade de São Paulo

The occurrence of extrafloral nectaries (EFN) in Passifloraceae species is very common, such that their presence and their shape are widely used as a diagnostic characteristic for species within this group. However, extrafloral glands in Passiflora foetida L., previously described as nectaries, were recognized as resin glands when the chemical nature of the exudate was analyzed, showing a distinct anatomical structure from the EFN. Therefore, we carried out an extensive anatomical, ultrastructural and chemical study of the leaf glands of Passiflora L. The goal was to establish clear morphological and chemical differences among the exudates of the observed glandular types. Usual techniques of plant anatomy, including scanning and transmission electron microscopy were used. In addition to histochemical tests for the in situ identification of the stored substances, techniques of thin layer chromatography and high performance liquid chromatography were respectively employed for the analysis of lipids and amino acids present in the exudates of the foliar glands. Ribbons of glucose test were also used as an aid to the recognition of carbohydrates and the definition of glands as nectaries. The EFN showed very varied forms, which were grouped as elevated or flattened nectaries, both with similar anatomy. Additionally, to having a large amount of sugars, extrafloral nectar also had amino acids and lipids in the composition. On the other hand, resin glands were observed to be morphologically and anatomically very distinct from the EFN. Besides not reacting to sugar tests, they chemically have a large amount of lipophilic substances, including a variety of terpenes and the presence of amino acids. The different techniques used allowed us to better define the glandular types and subtypes, emphasizing the differences between EFN and resin glands. New hypotheses were also proposed for the occurrence of resin glands in the group, increasing the number of species with this glandular type


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