A revision of PassifloraL.subgenusDecaloba(DC.) Rchb.supersectionCieca (Medik.) J. M. MacDougal & Feuillet (Passifloraceae)

Pliocene seeds of Passiflora subgenus Decaloba (Gray Fossil Site, Tennessee) and the impact of the fossil record on understanding the diversification and biogeography of Passiflora

PREMISE

Passiflora is a diverse genus of ~570 extant species primarily distributed in the Americas, from the eastern United States to Argentina and Chile. Nevertheless, the known fossil record of Passiflora is small. To date, only two fossil seed species have been unequivocally assigned to the genus. In this contribution, rare sulcate seeds from Gray Fossil Site are described as a third fossil seed species of Passiflora.

METHODS

Three partial seeds with sulcate sculpture from Gray Fossil Site, early Pliocene, Tennessee, USA, were examined, photographed, and measured. They were compared to samples of sulcate seeds from six extant Passiflora species in supersection Decaloba. A broader survey of sulcate seeds produced by modern species in the subgenera Decaloba, Deidamioides, and Tryphostemmatoides was done using published illustrations and descriptions.

RESULTS

The Gray Fossil Site seeds are described as Passiflora sulcatasperma, sp. nov., and assigned to subgenus Decaloba, supersection Decaloba. They are characterized by their small size, elliptical shape, ridged-and-sulcate sculpture, rugulose ridges, and thin palisade seed coat.

CONCLUSIONS

The two largest subgenera of Passiflora can be identified from Neogene fossils. Subgenus Decaloba is represented by two fossil seed species, P. bulgarica (Miocene, Bulgaria) and P. sulcatasperma (Pliocene, USA). Subgenus Passiflora is represented by fossil pollen (Miocene, Argentina and Brazil) and P. appalachiana seeds (Pliocene, USA). The distributions of fossil and modern species suggest that Passiflora may have used both North Atlantic and Antarctic routes to expand into Europe and the Asian-Oceanian Paleotropics, respectively.

Comparative Study of Ovule Development between Wild (Passiflora foetida L.) and Cultivated (P. edulis Sims) Species of Passiflora L. Provide Insights into Its Differential Developmental Patterns

The ovules inside the ovary of a plant are the precursors of seeds and they are important for the perpetuation of the plants. The genus Passiflora L., produce fruits with numerous seeds and they have economic and medicinal value. The edible portion of the Passiflora are the seeds surrounded by pulp. Being the edible parts of a fruit, it is important to investigate the early development of ovules in Passiflora that lead to the formation of seeds after pollination. Wild relatives of the domesticated crops are increasingly being investigated for possible genetic resources that can be used for crop improvement programs. The present study was designed to investigate the comparative ovule development between a wild (Passiflora foetida L.) and a cultivated (Passiflora edulis Sims) species of Passiflora with an aim that it may provide important information about the common and diverging regulatory mechanisms during ovule development between the wild and the cultivated species. We also investigated the pollen morphology between the wild and cultivated species using light and scanning electron microscopy. Our results show that wild type P. foetida ovule growth is faster when compared with that of cultivated P. edulis. Furthermore, wild species harbour ovules of large size (0.14 mm2) but less in number (6) as compared to cultivated ones which show smaller size (0.05 mm2) of ovules but relatively more in number (21). The differences in ovary wall thickness were also stark between the two species. The ovary wall thickness was 0.10 mm in the wild type whereas it was 0.74 mm in cultivated species. Notable differences were also observed in diameter where the wild type (2.45 mm) reported smaller diameter than cultivated species (3.25 mm). We observed little difference in the pollen morphology between the two species.

Strengthening Structures in the Petiole-Lamina Junction of Peltate Leaves

Peltate- or umbrella- shaped leaves are characterised by a petiole more or less centrally attached to the lamina on the abaxial side. The transition from the petiole to lamina in peltate leaves resembles a significant and abrupt geometrical change from a beam to a plate in a very compact shape. Since these leaves have not been subject of many studies, the distribution of that specific leaf morphology in the plant kingdom was investigated. Furthermore, the connection between the petiole and lamina of several peltate species was studied anatomically and morphologically, focusing on the reinforcing fibre strands. We found peltate leaves in 357 species representing 25 orders, 40 families and 99 genera. The majority are herbaceous perennials growing in shady, humid to wet habitats mainly distributed in the subtropical–tropical zones. Detailed anatomical investigation of 41 species revealed several distinct principles of how the transition zone between the petiole and lamina is organised. In-depth analysis of these different types accompanied by finite element-modelling could serve as inspiration for supporting structures in lightweight construction.

Chemical Composition of the Essential Oils From Leaves and Flowers of Passiflora sexocellata and Passiflora trifasciata

The chemical composition of the essential oils of Passiflora sexocellata and Passiflora trifasciata (Passifloraceae, subgenus Decaloba) were studied for the first time. Essential oils were obtained by steam distillation of fresh leaves and flowers. The chemical composition was assessed by using GC/FID and GC/MS. For P. sexocellata leaves, the optimized analytical procedure allowed the identification of 33 compounds (75% of the total oil composition) and 29 (74% of the total oil composition) in flowers. Regarding P. trifasciata, 35 compounds (76% of the total oil composition) were detected in leaves and 32 (71% of the total oil composition) in flowers. Terpenes and mono unsaturated hydrocarbons were quantified as major constituents of the volatile fraction in flowers (17.0 to 52.6%) and (13.7 to 20.0%). Organic acids were detected in both leaves and flowers with a percentage ranging from 3.3% to 32.0%. Aldehydes were also detected in leaves (12.6 to 41.4%) and in flowers (1.4 to 5.1%). The GC/MS analyzes allowed alcohols to be detected in leaves (20.6 to 42.9%) and in flowers (8.2 to 18.1%). These compounds represent the most important feature of the large Passiflora family. Moreover, a critical role in the coevolved mechanisms of pollinators' interaction has been investigated.

New trends in Passiflora L. pollen grains: morphological/aperture aspects and wall layer considerations

Passifloraceae shows a huge variability of pollen wall characteristics, most still little described. Passiflora is the largest genus with about 580 species with tropical distribution. Few studies in palynological approaches have described the intine layer which can fill existent gaps. Passiflora L. present four subgenera, from which Passiflora, Astrophea, and Decaloba were described in this study. The pollen wall variations were poorly studied, with the objective of describing the morphological and histochemical structure of Passiflora sporoderm that occurs in South America, aims to supply more pollen wall characters in some contexts. Besides the inference of evolutive trends, we described the number of apertures, type, reticule, and variations of the morphology and sporoderm and we related them with possible evolutive trends for the group. As a result, the pollen grains were not far from the patterns found by the literature, with exceptions. The species of the subgenus Passiflora have fused colpi, varying from 6 to 12 colpi, with type 2-reticulate exine. The species of the subgenus Astrophea have colporus and the species of Decaloba varied as the type of aperture, in which a new type of exine to be considered was found: the type 3. The subgenus Passiflora showed the thickest intine, slim endexine, and absent foot layer. While the species that belong to the other subgenera present a slim intine, the endexine is thick and the foot layer is continuous, among other variable characteristics. The size of the pollen grain seems to be related to the thickness of the intine, and consequently, related to possible pollinators. Through the cluster analysis, we reinforce the affinity of the species to its respective subgenus. To conclude, the analysis of the ultrastructure of the sporoderm and external morphology would be useful for an almost complete interpretation of the variations occurring in the genus, giving more information that the subgenus Passiflora is apomorphic when compared to the other two. The pollen wall characters should be considered on the interpretation of natural history, as well as the phylogenetic relationships of the family, mainly in the Passiflora genus, that has a large number of species distributed across the Neotropical regions.

Passifloraceae sensu stricto no Parque Estadual da Serra do Brigadeiro, Minas Gerais, Brasil

Resumo O presente estudo visou inventariar a diversidade taxonômica da família Passifloraceae sensu stricto no Parque Estadual da Serra do Brigadeiro (PESB), Minas Gerais e investigar os aspectos ecológicos relacionados à distribuição, estado de conservação e ocorrência das espécies em diferentes classes de altitude dentro da área de estudo. Foram identificadas 11 espécies pertencentes ao gênero Passiflora, a saber: P. alata, P. amethystina, P. capsularis, P. edulis, P. filamentosa, P. mediterranea, P. miersii, P. porophylla, P. rhamnifolia, P. Speciosa e P. tetraden, das quais quatro são novos registros de ocorrência para o PESB (P. alata, P. capsularis, P. filamentosa e P. rhamnifolia). A maioria das espécies está enquadrada em categoria de ameaça de extinção regional, com exceção de P. filamentosa e P. miersii, classificadas como "Deficiente de Dados", e P. speciosa e P. mediterranea consideradas "Menos Preocupante". Apenas P. alata e P. rhamnifolia atingiram as maiores elevações na área, em campos de altitude (1.700-1.800 m).

Revision of the Lima clade (Miconia sect. Lima, Miconieae, Melastomataceae) of the Greater Antilles

Miconia sect. Lima is an entirely Greater Antillean clade that consists of 19 known species of shrubs and small trees, which were previously recognized under the polyphyletic genera Leandra and Ossaea. The highest species richness in the clade is represented on Cuba (10 species), followed by Hispaniola (8 species) and then Jamaica (1 species). Here we present a taxonomic revision of the clade based on the study of species in the field, herbarium specimens, as well as a DNA-based phylogeny reconstruction. The Lima clade most likely originated on Cuba and then spread to Jamaica once and Hispaniola multiple times. Species of this clade can be recognized by the well developed bulla-based hairs of the adaxial leaf surface, as well as the clavate-dendritic hairs produced along the primary, secondary and tertiary veins of the adaxial leaf surface, mostly towards the leaf base, terminal inflorescences, acute petal apices, slightly bulla-based hairs produced subapically along the petal abaxial surface, and anthers with a dorso-basal appendage and a single, dorsally oriented pore. Descriptions, synonymies, along with distribution maps and illustrations/figures, are given for each species. Miconia pagnolensissp. nov. is newly described in this revision.