Pollen Morphology and Its Systematic Significance in the Ericaceae (original) (raw)
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(Vol.10, 2007-12) Pollen Morphology and Ultrastructure of Calyceraceae
2007
Pollen morphology of 13 species from all six genera of Calyceraceae (Acicarpha, Boopis, Calycera, Gamocarpha, Moschopsis, and Nastanthus) and representatives of the Campanulaceae and Goodeniaceae is examined with light (LM), scanning (SEM), and transmission (TEM) electron microscopy. Acicarpha, Calycera, and Nastanthus pollen grains are distinguished by angulaperturate apertures, colpar ledges and surface depressions between colpi known as intercolpar concavities (IC). Pollen of Gamocarpha and Moschopsis is tricolporate rather than angulaperturate and without an IC. Some species of Boopis are similar to the preceding genera (e.g., B. graminea), while others (e.g., B. gracilis) are angulaperturate with ICs. Structural features derived from fractured pollen in SEM and sections in TEM show pollen walls composed of prominent columellae ca. 0.55-1.1 mm high and ,0.25 mm wide. The columellae terminate distally into a complex of shortened columellae ca. 1.5 mm in length and are separated by an illdefined irregular internal tectum layer. This structural complex is well known in several tribes of the Asteraceae and referred to as the Anthemoid type. In those grains with an IC, the structure consists of essentially short (ca. 1 mm), unbranched columellae, similar to those found within the Asteraceae subfamily Barnadesioideae (Dasyphyllum and Schlechtendalia). Goodeniaceae (including Brunonia) pollen has angulaperturate apertures, spinules (i.e., minute spines), problematic IC and some structural similarity to Calyceraceae pollen. The tendency within Calyceraceae to develop colpar ledges, ektexine bridges, and ICs may be a synapomorphy uniting the family with Goodeniaceae. If the ancestral pollen type for the Calyceraceae, Asteraceae, and Goodeniaceae clade is the Gamocarpha type (convex intercolpar regions; no colpar ledges and no ektexine bridges), then the appearance of these structures within each family may be a synapomorphy supporting their close phylogenetic relationship suggested by molecular analyses.
Pollen Morphology and Ultrastructure of Calyceraceae
Lundellia
Pollen morphology of 13 species from all six genera of Calyceraceae (Acicarpha, Boopis, Calycera, Gamocarpha, Moschopsis, and Nastanthus) and representatives of the Campanulaceae and Goodeniaceae is examined with light (LM), scanning (SEM), and transmission (TEM) electron microscopy. Acicarpha, Calycera, and Nastanthus pollen grains are distinguished by angulaperturate apertures, colpar ledges and surface depressions between colpi known as intercolpar concavities (IC). Pollen of Gamocarpha and Moschopsis is tricolporate rather than angulaperturate and without an IC. Some species of Boopis are similar to the preceding genera (e.g., B. graminea), while others (e.g., B. gracilis) are angulaperturate with ICs. Structural features derived from fractured pollen in SEM and sections in TEM show pollen walls composed of prominent columellae ca. 0.55-1.1 mm high and ,0.25 mm wide. The columellae terminate distally into a complex of shortened columellae ca. 1.5 mm in length and are separated by an illdefined irregular internal tectum layer. This structural complex is well known in several tribes of the Asteraceae and referred to as the Anthemoid type. In those grains with an IC, the structure consists of essentially short (ca. 1 mm), unbranched columellae, similar to those found within the Asteraceae subfamily Barnadesioideae (Dasyphyllum and Schlechtendalia). Goodeniaceae (including Brunonia) pollen has angulaperturate apertures, spinules (i.e., minute spines), problematic IC and some structural similarity to Calyceraceae pollen. The tendency within Calyceraceae to develop colpar ledges, ektexine bridges, and ICs may be a synapomorphy uniting the family with Goodeniaceae. If the ancestral pollen type for the Calyceraceae, Asteraceae, and Goodeniaceae clade is the Gamocarpha type (convex intercolpar regions; no colpar ledges and no ektexine bridges), then the appearance of these structures within each family may be a synapomorphy supporting their close phylogenetic relationship suggested by molecular analyses.
The present studies of anther types (based on their mode of dehiscence) accounted for 206 angiospermic species belonging to 140 genera of 45 families. Two main types of anther dehiscence were observed viz., longitudinal and poricidal. Among the subtypes of longitudinal dehiscence, latrorse type is most common found in 114 species, followed by extrorse and introrse types in 49 and 28 taxa respectively. There are only 15 species which dehisce their anthers by apical pores. The families Amaranthaceae, Apocynaceae and Compositae have introrse anther dehiscence, whereas, poricidal type is specific for the genera Cassia, Pedalium, Polygala, Senna and Solanum.
Pollen wall ultrastructure of the genus Adansonia L. species
Plant Systematics and Evolution, 2014
The genus Adansonia (baobabs, Malvaceae) includes nine tropical species grouped in the Brevitubae, Longitubae and Adansonia sections. The ultrastructure of pollen from eight species of baobabs was studied using transmission electron microscopy. The pollen grains correspond to 3-colporate and 4-colporate types. The ectexine is formed by a perforate tectum with isolated spinules. An important distinguishing feature between the Brevitubae section and the Longitubae and Adansonia sections was observed in the infratectum. The apertural region was similar in all the species studied here. However, the most unusual structure was observed in the apertural margins where the ectexine consisted of a thick lamellate annulus and the endexine had a cracked appearance; the intine was composed of a well-developed oncus under the endopore with unusual fibrillar structures and the outer layer had a remarkable structure consisting of columns. Despite the few differences observed in the structure of the pollen wall within the genus, an original arrangement of the structure found in the aperture of the Adansonia pollen grains studied provides additional information about the new types of apertural structures. This type of sporoderm adds to our knowledge of the diversity of angiosperm pollen. Moreover, this apertural structure is probably an adaptation that occurs during the formation of the pollen tube and of harmomegathy.
Exine structure in Cecropia L. (Moraceae) pollen grains
Boletim IG-USP. Publicação Especial, 1989
Species of the genus Cecropia have very small pollen grains. The exine stratification and surface ornamentation are here elucidated by means of electron microscope observations. The ten species studied may be divided into two groups according to the distribution of spinules over the pollen grain surfaces: one group with uniform distribution and the other with spinules only at equatorial regions so that the polar areas are nearly smooth. From the surface inward, the exine presents supratectal spinules; a well formed tectum t raversed by very small channels; short and fine bacula; a discontinuous nexine 1 and a cont inuous nexine 2, which is thicker around the pores. With respect to the differentiation of t hc exine structure, Gecropia exhibits a degree of evolution within the Moraceae family, which argues against any approximation of this genus to the Urticaceae family. RESlMJ Devido ao pequeno tamanho dos grãos de pólen de especles do gênero Cecropia, é elucidada no presente trabalho a estratificação da exina e a ornamentação das superfícies por meio de observações em microscopia eletrônica. As 10 espécies estudadas podem ser separadas em dois grupos segundo a distribuição dos espículos na superfície dos grãos de pólen: distribuição uniforme com espículos acumulados na faixa equatorial, deixando as áreas polares praticamente lisas. A exina é estruturada de fora para dentro por espículos supratectais, de um teto bem desenvolvido atravessado por diminutos canalículos, báculos curtos e delgados, uma nexina 1 descontínua e uma nexina 2 contínua, espessada em volta dos poros. De acordo com estas diferenciações da estrutura da exina, o gênero Cecropia apresenta dentro da família Moraceae um certo grau de evolução que não apoia a sua aproximação à família Urticaceae.
© TÜBİTAK Contributions to the Pollen morphology of the family Compositae
2015
Abstract: The pollen morphology of 24 species of Compositae belonging to 18 genera was examined by light and scanning microscopy. The present data confirms the eurypalynous nature of the family. Delimitation of the genera on the basis of pollen characters is less marked. Pollen grains usually radially symmetrical, isopolar rarely apolar; tricolporate, often porate. Shape commonly oblate-spheroidal to prolate-spheroidal, with some suboblate to subprolate types. Tectum echinate to echinolophate, often non-echinate. Tectum in-between the spines or spinules is sub-psilate, or perforated to striate. On the basis of the exine pattern, 4 distinct pollen types are recognized viz.,
Glossary of pollen and spore terminology
The glossary of pollen and spore terminology was first presented to the international palynological community as the final outcome of the Working Group on Palynological Terminology at the 8th International Palynological Congress in Aix-en-Provence in 1992. It became widely accepted as reference guide for palynologists to assist in the preparation of accurate and consistent descriptions of their material. It also serves as a practical source of information for non-specialists who wish to understand the meaning of the large number of existing palynological terms.
Plant Systematics and Evolution, 2007
To better understand the relationships within the Asteroideae and Inuleae, the structure of the pollen exine was investigated in seven genera and nine species of the subtribe Inulinae using LM, TEM and SEM. All taxa have a senecioid pattern of exine. The tectal complex consists of three main layers that differ in thickness and morphology: a tectum, a columellar layer, and a layer consisting of the basal region of the columellae. The absence or the vestigial condition of the foramina is considered as a plesiomorphy within the Asteroideae. All taxa have a complex apertural system that consists of an ecto-, a meso-, and an endoaperture. These apertures intersect respectively the tectal complex, the foot layer and the upper part of the endexine, and the inner layer of the endexine. A continuous transition among the different species of Inulinae was found for all the quantitative characters examined. This relative homogeneity of the pollen morphological characters enhances the naturality of the subtribe Inulinae.