Lilian Mónica Passarelli

Significance of floral colour and scent in three Solanum sect. Cyphomandropsis species (Solanaceae) with different floral rewards

The role of scent and floral colour in three Solanum sect. Cyphomandropsis species with different floral rewards was studied. In the two studied species with pollen rewards, S. glaucophyllum Desf. and S. stuckertii Bitter, the principal advertisement to pollinators is the colour of the perianth and anthers, including areas that absorb UV light. In the last species, the scent emitted by the osmophores of the connective also plays a significant role in flower attraction. The floral perfume would be the only advertisement in species such as S. adelphum Morton, with perfume reward in which the cryptical anther colour does not contrast with that of the perianth. The internal face of the petals remains hidden. In this case no differences in the patterns of areas that absorb visible light and UV light were found. The main visitors to Solanum are species of Bombus and Augochloropsis. These pollinators visit S. glaucophyllum and S. stuckertii, species with pollen reward, but they do not visit flowers with perfume reward, for example S. adelphum.

Spore morphology and ornamentation in the genus Blechnum (Blechnaceae)

Abstract A study of the spores of 64 neotropical and palaeotropical taxa of the genus Blechnum was performed using scanning electron microscopy (SEM). Two basic types of perispores were recognised: perispore smooth or only slightly ornamented (laevigate, with micro-granules or micro-lamellae, venulose and rugulate), and perispore ornamented (rugate, low reticulate, cristate-reticulate, orbiculate, and colliculate). SEM observations allow for distinguishing differences in the structure of perispores, but the character does not correlate with the ornamentation. The smooth exospore predominates among the studied species. Results suggest that perispore characters have important diagnostic value, since different combinations of ornamentation/structure were found among the studied species. Moreover, when spore characters are considered together with other morphological traits of the sporophytes and the habit of plants, ornamentation of spores becomes a useful complementary feature at the specific level. The results are discussed in light of the recent systematic studies and emphasise that any eventual subdivision of the genus Blechnum must include characters of the sporophyte as well as spore features to ensure a more robust classification than the previously proposed. The spores also show a significant affinity between Blechnum and other genera of Blechnaceae, which was also suggested by recent phylogenetic studies.

Dynamics of pollen release in relation to anther-wall structure among species of Solanum (Solanaceae)

Dynamics of pollen release in relation to anther-wall structure among species of Solanum (sects Brevantherum, Cyphomandropsis and Pachyphylla) were studied. Differences in anther-wall qualities (multi-layered and rigid v. single-layered and flexible) were correlated with shifts between vibratory and pneumatic mechanisms. The species presented different exploitation mechanisms for bees to obtain their pollen. The number of replications (strokes on the bellows and buzzing actions) needed to empty the anthers and the total amount of pollen per flower were significantly different among the species. However, the differences were not correlated with differences in structural anther features. The pollination syndrome was related only to the total amount of pollen per flower, which was larger in the pollen flowers. We propose that the pneumatic mechanisms may have played a role simultaneously with the vibratory mechanism as an unclogging device or as a means of increasing male fitness by the pattern of pollen distribution. The pre-existence of the pneumatic principle in pollen flowers must have opened the possibility of pollen deposition on visitors without vibratory capabilities such as a male bee. Parallel to this change a shift in the reward system must have occurred.

Morphology of the sporophyte and gametophyte of the swamp fern, Blechnum serrulatum (Blechnaceae, Pteridophyta)

In the present paper, we provide a revised, comprehensive description of the sporophyte and gametophyte of the swamp fern, Blechnum serrulatum Rich., from neo- and paleotropical localities. External and internal characters of the sporophyte were analysed, including axes, laminae, pinnae, indusia and spores. Intercellular pectic connections of the parenchyma of the rhizomes are reported for the first time. In stipes, cell walls of the aerenchyma tissue contain filamentous protuberances that are composed primarily of cellulose but contain also fatty substances. The morphology of the gametophyte, from spore germination to gametangia formation, is discussed. The taxonomic significance of the characters is considered, especially in regard to the relationship between B. serrulatum and the closely related B. indicum.

Sporogenesis, sporoderm and mature spore ornamentation in Lycopodiaceae

Sporogenesis, sporoderm and mature spore ornamentation in Lycopodiaceae. Studies on reproductive aspects, spore morphology and ultrastructure of Lycopodiaceae are not very common in the scientific literature, and constitute essential information to support taxonomic and systematic relationships among the group. In order to complete existing information, adding new and broader contributions on these topics, a comparative analysis of the sporogenesis ultrastructure, with emphasis on cytological aspects of the sporocyte coat development, tapetum, monoplastidic and polyplastidic meiosis, sporoderm ontogeny and ornamentation of the mature spores, was carried out in 43 taxa of eight genera of the Lycopodiaceae: Austrolycopodium, Diphasium, Diphasiastrum, Huperzia (including Phlegmariurus), Lycopodium, Lycopodiella, Palhinhaea and Pseudolycopodiella growing in the Andes of Colombia and the Neotropics. For this study, the transmission electron microscopy (TEM) samples were collected in Cauca and Valle del Cauca Departments, while most of the spores for scanning electron microscopy (SEM) analysis were obtained from herbarium samples. We followed standard preparation procedures for spore observation by TEM and SEM. Results showed that the sporocyte coat is largely composed by primary wall components; the sporocyte develop much of their metabolic activity in the production of their coat, which is retained until the spores release; protective functions for the diploid cells undergoing meiosis is postulated here for this layer. The abundance of dictyosomes in the sporocyte cytoplasm was related to the formation and development of the sporocyte coat. Besides microtubule activity, the membrane of sporocyte folds, associated with electrodense material, and would early determine the final patterns of spore ornamentation. Monoplastidic condition is common in Lycopodium s.l., whereas polyplastidic condition was observed in species of Huperzia and Lycopodiella s. l.. In monoplastidic species, the tapetum presents abundant multivesicular bodies, while in polyplastidic species, the secretory activity of the tapetum is less intense. Sporoderm development is centripetal, exospore is the first formed layer, then the endospore and, if present, perispore is the final deposited layer. Adult spores of the Lycopodiaceae showed two patterns of ornamentation: negative or caviform (foveolate spores) and positive or muriform ornamentation, the latter with two subtypes (rugate and reticulate spores). The spores of Huperzia are characteristically foveolate, the rugate spores were found in a few species of Huperzia and in all of the Lycopodiella s. l. taxa studied, while Lycopodium s.l. spores bear reticulate ornamentation. Numerous ornamentation traits are diagnostic at the specific level. The types of ornamentation found do not support the recent extreme fragmentation of the family in several genera, but could match, a priori, with the idea of three subfamilies. The findings of sporogenesis, extremely similar in all taxa studied, point more to consider fewer genera, more comprehensive, than the recent, marked splitting of the family. Rev. Biol. Trop. 62 (3): 1161-1195. Epub 2014 September 01.

Pollen grains and pollinia in four Southamerican palustrine species of Habenaria (Orchidaceae)

Abstract The massulae and pollen grains in pollinia of four palustrine South American species of Habenaria, H. bractescens, H. gourlieana, H. paucifolia and H. secunda were studied here for the first time using light, scanning, and transmission electronic microscopy. The pollinia have acalymmate, piriform or tabular massulae. Filiform elastoviscin threads are formed between the pollen grains of pollinia, allowing them to stick together. The pollen grains are inaperturate, grouped into calymmate tetrads, and have reticulate or reticulum-like, heterobrochate exine. Reticulate ornamentation consists of irregular, rounded, wide or narrow, continuous muri, while reticulum-like ornamentation is formed by discontinuous, partial muri, superficially smooth or with spherical micro-granules, intermingling with some isolated elements that can be interpreted as pila. The wall structure of individual pollen grains differs according to their position in the tetrads: outside walls develop complete exine and intine, with columellae, while the walls inside the pollinium lack exine or develop only a much reduced one. Palynological characters differentiate the species: pyriform massulae, triangular in outline, occur in H. gourlieana, H. paucifolia and H. secunda, while tabular massulae, oblong in outline, characterise H. bractescens. Ornamentation also distinguishes H. gourlieana grains, with interrupted, discontinuous muri, from the other three species, bearing reticulate grains. Elastoviscin filiform threads, which were found to be lipidic in nature, are simple or ramified, and some bear pores (in H. bractescens). Branched filiform threads characterise H. bractescens and H. secunda, while unbranched, filiform threads correspond to H. gourlieana and H. paucifolia.

Pollen grains and massulae in pollinia of four South American palustrine species of Habenaria (Orchidaceae)

Abstract The massulae and pollen grains in pollinia of four palustrine South American species of Habenaria, H. bractescens, H. gourlieana, H. paucifolia and H. secunda were studied here for the first time using light, scanning, and transmission electronic microscopy. The pollinia have acalymmate, piriform or tabular massulae. Filiform elastoviscin threads are formed between the pollen grains of pollinia, allowing them to stick together. The pollen grains are inaperturate, grouped into calymmate tetrads, and have reticulate or reticulum-like, heterobrochate exine. Reticulate ornamentation consists of irregular, rounded, wide or narrow, continuous muri, while reticulum-like ornamentation is formed by discontinuous, partial muri, superficially smooth or with spherical micro-granules, intermingling with some isolated elements that can be interpreted as pila. The wall structure of individual pollen grains differs according to their position in the tetrads: outside walls develop complete exine and intine, with columellae, while the walls inside the pollinium lack exine or develop only a much reduced one. Palynological characters differentiate the species: pyriform massulae, triangular in outline, occur in H. gourlieana, H. paucifolia and H. secunda, while tabular massulae, oblong in outline, characterise H. bractescens. Ornamentation also distinguishes H. gourlieana grains, with interrupted, discontinuous muri, from the other three species, bearing reticulate grains. Elastoviscin filiform threads, which were found to be lipidic in nature, are simple or ramified, and some bear pores (in H. bractescens). Branched filiform threads characterise H. bractescens and H. secunda, while unbranched, filiform threads correspond to H. gourlieana and H. paucifolia.