Sporoderm morphogenesis in Euphorbia obesa and Croton gratissimus

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 849-856 ◽  
Author(s):  
M. L. Frean
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Physiological Adaptation ◽  
Structure Characteristic ◽  
Pollen Type ◽  
Electron Microscope Level ◽  
Pollen Characters ◽  
Pollen Types ◽  
Unisexual Flowers ◽  
Taxonomic Grouping

Pollen grains of the Euphorbiaceae show a number of pollen types which can be clearly distinguished. Generally different genera are characterized by a specific pollen type.  Euphorbia obesa Hook. f. and Croton gratissimus Burch, subsp.  subgratissimus (Prain) Burtt Davy, represent two genera within the Crotonoideae with different morphology, each type characteristic for the respective genus. Taxonomically, the genus Euphorbia with apetalous flowers consisting of a naked pistil surrounded by several staminate flowers within a cyathium, is considered more advanced than the genus  Croton. In  Croton the inflorescence is a raceme with unisexual flowers. The floral whorls of the male show numerous anthers and both calyx and a showy corolla are present. Both genera are insect pollinated. In both  Euphorbia obesa and  Croton gratissimus the pollen wall in section shows columellae, a structure characteristic of angiosperms. However the present ontogenetic studies show that the formation of the columellae differs entirely in the two pollen types. The final stratification of the wall as well as the morphology of the grains differ and evaluation of the exine structure indicates that phylogenetically Croton pollen shows more advanced characters than  Euphorbia — contradicting the floral phylogeny. This study conducted at light and electron microscope level compares the two pollen types morphologically and ontogenetically, concentrating mainly on the formation of the exine which is tectate-perforate in the prolate tricolpate grain of Euphorbia obesa and semi-tectate in the anaperturate, spheroidal grain of Croton gratissimus. The aim of the study was to evaluate the significance of pollen characters in taxonomic and phylogenetic relationships within the Euphorbiaceae. The differing pollen morphology which is related to the taxonomic grouping of tribes within the subfamily (Crotonoideae) emphasizes diversity, which may result from physiological adaptation. The study shows that the same functional end may well be achieved in different ways and this may be a factor underlying the diversity in the heterogeneous family Euphorbiaceae.

scholarly journals Pollen characters as taxonomic evidence in some species of Dipsacaceae from Iran

2017 ◽  
Vol 24 (2) ◽  
pp. 129-136 ◽  
Author(s):  
Ebadi-Nahari Mostafa ◽  
Nikzat-Siahkolaee Sedigheh ◽  
Eftekharian Rosa
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Pollen Grain ◽  
Pollen Type ◽  
Upgma Tree ◽  
Pollen Characters ◽  
Exine Ornamentation ◽  
The Family ◽  
The World ◽  
Plant Taxon

Pollen morphology of nine species representing four genera: Cephalaria Schrad, Dipsacus L., Pterocephalus Vaill. and Scabiosa L. of the family Dipsacaceae in Iran has been investigated by means of scanning electron microscopy (SEM). The results showed that pollen grains were triporate and tricolpate. The pollen type of Scabiosa rotata Bieb. (tri- and tetraporate) is the first report in the world. The sizes of pollen grains fall into the classification group magna (pollen grain diameter 50–100 μm). Pollen shapes vary from preoblate to prolate and their polar views were triangulate and lobate. The exine ornamentation varies from gemmate in S. rotata to spinulate in the rest studied species. Species of Scabiosa have been dispersed in UPGMA tree that this confirmed the previous studies about taxonomic problems and species complexity in this genus. These results show the transfer of the some Scabisoa species to Lomelosia Raf. based on palynological characters. Pollen morphology of the family is helpful at the generic and specific level.Bangladesh J. Plant Taxon. 24(2): 129–136, 2017 (December)

Morphologie pollinique des Cupressaceae de l'est du Canada et du nord-est des États-Unis appliquée à l'étude des sédiments quaternaires

1990 ◽  
Vol 68 (1) ◽  
pp. 79-89 ◽  
Author(s):  
Johanne Parent ◽  
Pierre J. H. Richard
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Taxodium Distichum ◽  
Juniperus Virginiana ◽  
Eastern Canada ◽  
Pollen Type ◽  
Thuja Occidentalis ◽  
Chamaecyparis Thyoides ◽  
Identification Criterion ◽  
Pollen Types

The pollen morphology of seven species, varieties and forms of Cupressaceae from eastern Canada and northeastern United States was studied by light microscopy, following acetolysis, to improve the identification of these taxa in Quaternary fossil sediments. Taxodium distichum (Taxodiaceae), which is also present in the study area, was included for comparison. Four pollen types were defined: Juniperus communis – Thuja occidentalis, Chamaecyparis thyoides, Juniperus horizontalis – Juniperus virginiana, and Taxodium distichum. Five shapes of pollen grains exist: whole, slightly split, opened in a "V" shape, spindlelike, or split in halves. All shapes are found in all species, in varying proportions, and represent different stages of hydration in Cupressaceae pollen type. The absence or presence of these shapes cannot be used as an identification criterion for the different species. A pollen identification key, applicable to fossil sediments and combining characters based on shape, size and other morphological features of acetolysed grains, is proposed and allows to differentiate all the species from one another, with the exception of Juniperus horizontalis and Juniperus virginiana.

The systematic value of pollen morphology of Passiflora subgenus Astrophea (Passifloraceae)

Phytotaxa ◽  
2017 ◽  
Vol 298 (1) ◽  
pp. 1 ◽  
Author(s):  
ANA CAROLINA MEZZONATO-PIRES ◽  
CLÁUDIA BARBIERI FERREIRA MENDONÇA ◽  
MICHAELE ALVIM MILWARD-DE-AZEVEDO ◽  
VANIA GONÇALVES-ESTEVES
Keyword(s):  
Great Degree ◽  
Pollen Morphology ◽  
Multivariate Analyses ◽  
Type I ◽  
Pollen Type ◽  
Type Iv ◽  
Quantitative Characters ◽  
Pollen Characters ◽  
Pollen Types ◽  
Degree Of Similarity

This study investigates and reports the pollen morphology of a selected group of Passiflora species of the subgenus Astrophea. We found that species can be grouped into five pollen types, four of which had been previously documented. The fifth new pollen type was observed in P. macrophylla. This pollen type completely lacks muri, and possesses spines and bacula on a granulate surface. All of the species of the subgenus Astrophea studied have the same type of aperture: 6-colporate with 3 lalongate endoapertures, one for each pair of ectoapertures. Multivariate analyses performed with quantitative characters showed a great degree of similarity between type I, II and V pollen, and individual distinction of type III and type IV. The pollen characters observed do not support the currently accepted taxonomic classification for the Passiflora subgenus Astrophea, but are useful for delimiting species.

Pollen morphology of some Paronychia species (Caryophyllaceae) from Turkey

Biologia ◽  
2008 ◽  
Vol 63 (1) ◽  
Author(s):  
Ayşe Kaplan
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Pollen Size ◽  
Pollen Type ◽  
Pollen Types ◽  
Exine Sculpturing ◽  
Scanning Electron

AbstractThe Pollen morphology of 13 taxa 11 of which are endemics belonging to Paronychia Miller (Caryophyllaceae) viz., P. agryloba, P. angorensis, P. arabica subsp. euphratica, P. carica, P. cataonica, P. chinonea, P. condensata, P. davisii, P. dudleyi, P. galatica, P. kurdica subsp. kurdica, P. kurdica subsp. montis-munzur and P. mughlaei from Turkey has been investigated by light (LM) and scanning electron microscopy (SEM). LM observations show that pollen grains are usually radially symetrical, isopolar, pantoporate, polygonal (6-gonal) or polygonal-spheroidal. Tectum is psilate or punctate. Tectal surface sparsely-densely spinulose. The numbers of pores are between 6 and 12. On the basis of pollen sizes, P. davisii was the biggest pollen type (23.45 µm) and P. kurdica subsp. kurdica (16.2 µm) was the smallest pollen types. According to exine sculpturing, pollen size and spinule numbers per 1 µm2, three pollen types were distinguished.

scholarly journals Pollen morphology of the Myrtaceae. Part 2: tribes Backhousieae, Melaleuceae, Metrosidereae, Osbornieae and Syzygieae

2012 ◽  
Vol 60 (3) ◽  
pp. 200 ◽  
Author(s):  
Andrew H. Thornhill ◽  
Geoff S. Hope ◽  
Lyn A. Craven ◽  
Michael D. Crisp
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Light Microscopy ◽  
Pollen Morphology ◽  
Size Variation ◽  
Pollen Grains ◽  
Pollen Type ◽  
Diagnostic Characters ◽  
Pollen Types ◽  
Scanning Electron

Pollen morphology of 16 genera and 101 species from the Myrtaceae tribes Backhousieae, Melaleuceae, Metrosidereae, Osbornieae and Syzygieae was surveyed using scanning electron microscopy (SEM) and light microscopy (LM). The most common pollen type observed in these tribes was parasyncolpate with arcuate or angular colpi, and a rugulate exine pattern. There was little size variation in observed pollen, except for larger pollen in tribe Melaleuceae. All Metrosideros pollen grains had apocolpial islands, as well as all Callistemon species viewed by LM. Choricarpia of tribe Backhousieae had pollen with a distinctive exine pattern. Dicolporate pollen were observed in two tribes, Metrosidereae (Tepualia) and Syzygieae (Acmena), and may be of systematic value. The dicolporate grains of these two genera were also easily distinguishable from each other by using size and pollen side shape as diagnostic characters. Two pollen types were observed within the genus Melaleuca, and a number of pollen types were observed within the species-rich genus Syzygium.

Pollen morphology of Youngia and six related genera (Asteraceae: Cichorieae) and its systematic significance

Phytotaxa ◽  
2013 ◽  
Vol 139 (1) ◽  
pp. 39 ◽  
Author(s):  
YU-LAN PENG ◽  
XIN-FEN GAO ◽  
LU PENG
Keyword(s):  
Pollen Morphology ◽  
Polar Region ◽  
Morphological Diversity ◽  
Systematic Position ◽  
Pollen Data ◽  
Generic Level ◽  
Pollen Characters ◽  
Pollen Types ◽  
Sectional Classification

The pollen morphology of 15 species representing four sections of Youngia and 11 species from six other genera of the tribe Cichorieae was investigated. Measurements and observations were conducted through scanning electron microscopy. This study aims to provide new and useful information regarding the extent of pollen morphological diversity within the genus Youngia and related genera in the tribe Cichorieae and thus to contribute to a better understanding of the taxonomy and evolution of these groups. Six pollen types, distinguished primarily by the number of apertures and spines in the polar region, are described. Palynological characters are not useful for the delimitation of Youngia and its closely related genera Crepidiastrum, Ixeridium, and Crepis at the generic level, and did not fully resolve the relationships between the groups. The distinction of Faberia from the other members of the subtribe Crepidinae is supported by the pollen characters. Pollen morphology also did not support that Youngia sect. Desiphylum sensu Babcock and Stebbins may be separated at the generic level either as Tibetoseris or Pseudoyoungia. Four pollen types were found in Youngia s.l., i.e. Y. racemifera type, Y. japonica type, Y. prattii type and Y. sericea type, which partly reflect the sectional classification of Youngia sensu Babcock and Stebbins. The systematic position of Y. racemifera should be reconsidered according to pollen characters. The pollen data suggest that Y. sect. Mesomeris is not monophyletic, and the relationships of its species require further examination.

scholarly journals Palynological analysis of genus Geranium (Geraniaceae) and its systematic implications using scanning electron microscopy

Caryologia ◽  
2021 ◽  
Vol 74 (3) ◽  
pp. 31-43
Author(s):  
Jun Wang ◽  
Qiang Ye ◽  
Tong Zhang ◽  
Xusheng Shi ◽  
Majid Khayatnezhad ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Pollen Grains ◽  
Prolate Spheroid ◽  
Multivariate Statistical ◽  
Pollen Characters ◽  
Pollen Types ◽  
Ward Clustering ◽  
The Relationship ◽  
Scanning Electron

Pollen morphology of 23 species belonging to Geranium have been studied in details, which represent eight sections of two subgenera i.e., G. sect. Dissecta, Geranium, and Tuberosa of subgen. Geranium, Divaricata, Lucida, Ruberta and Trilopha of subgen. Robertium. These plant species were collected from different phytogeographical regions of Iran. The palynological investigation was done using scanning electron microscopy (SEM) techniques. Different palyno-morphological features have been observed, and the closely related species were distinguished. We used different multivariate statistical methods to reveal the species relationships. Ward clustering analyses have been done to check out the relationship among the species. The shapes of pollen grains were monad, radially symmetric, isopolar, apertures were tricolporate, and of spheroid, prolate-spheroid or sub-prolate classes. Three pollen types were recognized on the basis of differences in exine sculpturing pattern: reticulate-clavate, striate-rugulate, reticulum cristatum with clavae. Observed differences were not of diagnostic importance in subgenera and sections level. The main objective of this study is to find distinguish pollen characters in the species of the genus Geranium and to elucidate their systematics importance.

Pollen morphology of Stellaria (Caryophyllaceae) from China and its systematic implications

Phytotaxa ◽  
2020 ◽  
Vol 429 (2) ◽  
pp. 91-119 ◽  
Author(s):  
HAN-FENG XU ◽  
YU-HUI JIANG ◽  
ZHI-WEI SU ◽  
ZHONG-HUI MA
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Morphological Features ◽  
Pollen Types ◽  
The Family ◽  
Pore Number

Pollen morphology of 46 species and 11 varieties representing the 5 currently recognized sections and 10 series of Stellaria from China was investigated. Pollen grains of Stellaria are radially symmetrical, apolar, small or medium in diameter, pantoporate, spheroidal or spheroidal-polyhedral and have 8–22 pores with prominent or sunken pore membrane. The ornamentation is microechinate-punctate, microechinate-perforate or microechinate-punctate-perforate. 8 pollen types are recognized, and significant differences in shape, size, pore number and ornamentation are found. Arenaria and Cerastium were proved to be related to Stellaria, whereas Myosoton was suggested to be merged into Stellaria. The pollen morphological features indicated Stellaria was in a middle evolutionary position of the family Caryophyllaceae.

scholarly journals Pollen morphology of section Cheirolepis Boiss. of the genus Centaurea L. (Asteraceae) in Turkey

2019 ◽  
Vol 26 (2) ◽  
pp. 131-148
Author(s):  
Burcu Yilmaz Çitak ◽  
Hüseyin Dural ◽  
Tuna Uysal ◽  
Nur Münevver Pinar
Keyword(s):  
Electron Microscope ◽  
Clustering Analysis ◽  
Pollen Morphology ◽  
Pollen Grains ◽  
Base Length ◽  
Diagnostic Features ◽  
Spine Length ◽  
Pollen Characters ◽  
Pollen Shape ◽  
Scanning Electron

In this paper, the palynomorphology of 17 taxa of section Cheirolepis in Turkey, were investigated by light (LM) and scanning electron microscope (SEM). Detailed descriptions of the pollen grains were given for each taxon and a well-resolved dendrogram was generated through numerical analysis of palynological diagnostic features. The pollen grains were found to be radially symmetric, isopolar, and generally 3-zonocolporate, with the exception of C. derderiifolia, C. kotschyi var. floccosa, and C. saligna, which were also 4-zonocolporate. The shape of the pollen grains were prolatespheroidal, with the polar axes of 32.76–46.26 μm and equatorial axes of 31.86–45.82 μm. The sculpturing of the pollen grains was generally scabrate-perforate or rarely microechinate-perforate. The spines were conical with a changing base length. The length and the width of the spines varied between 0.48 and 2.28 μm and 0.4 and 3.39 μm, respectively. The number of perforations at the base of the spines ranged in two or morerows and they varied between 5 and 30. The number of spines was 16–70 in 10 μm2. The results of this study showed that the polar axes, equatorial axes, aperture type, pollen shape, spine length, perforation number, and number of spines in 10 μm2 are essential for distinguishing the studied taxa. The taxa were grouped by clustering analysis of selected pollen characters using the UPGMA method.

Pollen morphology in Dodartia, Lancea, Leucocarpus, and Mazus and an analysis of pollen morphotypes in the Mimuleae (Scrophulariaceae)

1984 ◽  
Vol 62 (6) ◽  
pp. 1287-1297 ◽  
Author(s):  
Charles L. Argue
Keyword(s):  
Pollen Morphology ◽  
Pollen Grains ◽  
Morphological Characters ◽  
Pollen Data ◽  
Pollen Types ◽  
Taxonomic Implications

The pollen grains of Dodartia, Lancea, Leucocarpus, and Mazus are single, radially symmetrical, isopolar, and suboblate to prolate with trizoniaperturate ectocolpi; the colpus membranes show various patterns of transverse rupturing but most frequently have a single, equatorial rupture. The exine is composed of a semitectate sexine 2, a simplicolumellate sexine 1, and a frequently foveolate to perforate nexine, thinner than the sexine. Data from the present and earlier studies on the Mimuleae are analyzed statistically to establish a specific set of correlated morphological characters with discriminatory value in the definition and delimitation of major pollen types for the tribe. Interspecific and intergeneric palynological variation among tricolporate Mimuleae is assessed and taxonomic implications of the pollen data are discussed.

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