ULTRASTRUCTURE OF PARKIA POLYADS (MIMOSOIDEAE: LEGUMINOSAE)

Pollen of 16 species of Parkia (ca. 30 spp.) was examined in the light, scanning and transmission electron microscopes (LM, SEM and TEM). Pollen is shed as large (61-236 μm), globose, 16–32-grained polyads that remain united following acetolysis. Thin sections reveal that polyad cohesion is maintained through fusion and/or adhesion and/or appression of adjacent ektexines in lateral and/or proximal and/or distal regions. In lateral and proximal regions the ektexine is often embedded in a dense granular endexinous matrix. Individual grains of the polyad are clearly outlined in most species but are completely obscured in several New World species. Sculpturing varies both in pattern and type of element. Nonuniformly sculptured polyads, in which the sculpturing of individual grains differs between the peripheral and central portions of the distal face, occur only among Old World species. Uniformly sculptured polyads occur among both New and Old World taxa. Two main sculpturing types are present among Parkia species: verrucate and tectate-perforate, the latter particularly well developed in the reticulate polyads of the neotropical P. ulei and P. multijuga p.p. Ultrastructurally, all Parkia polyads exhibit ektexine and endexine continuous around the individual grain. Distal ektexine is prominent and clearly stratified, usually exhibiting a thick, perforate tectum, columellate interstitium, and a thin, locally discontinuous foot layer. Lateral and proximal ektexine is significantly thinner and less structured. Individual grains within the polyad possess three to four peripheral-distal apertures usually at the points of contact between adjacent grains. Proximal and central grain apertures occur in most, but not all, species. Polyad characters suggest a particularly close relationship among the New World species P. decussata, P. discolor, P. gigantocarpa, P. igneiflora, and P. nitida. Parkia ulei, though sculpturally closest to P. multijuga p.p., is ultrastructurally most similar to the African P. biglobosa. The large tectate-perforate-fossulate polyads of P. pendula and P. platyparkia are unique in the New World.     

Pollen morphology and pollen-wall proteins (localization and enzymatic activity) inSesamothamnus lugardii (Pedaliaceae)

The pollen grains ofSesamothamnus lugardii Stapf (Pedaliaceae of subdesert regions of SE tropical Africa) are associated in acalymmate tetrads (cross wall cohesion), with a tectate and perforate exine and 8–12 colpi. The pollen wall consists of an ectexine with a complete, perforate and ample tectum, columellated infratectum and clearly interrupted and fragmented foot layer. The endexine is built of scanty lamellae and granules. The intine is bistratificate, with a homogeneous, fibrillate layer (endintine or intine-2) and a heterogeneous, more lax and channeled layer (exintine or intine-1). Test for glycoprotein is particularly positive in the homogeneous internal intine and channels of external intine. On the other hand acid phosphatase has been localized in the exine and channeled external intine layers. These observations confirm the general interpretation of the distribution of wall compounds.     

Pollen morphology in thePortulacaceae (Centrospermae)

Pollen of 110 species from 18 genera in thePortulacaceae has been examined by light and scanning electron microscopy, and a representative number by transmission electron microscopy. Three basic pollen types were found: 3-colpate with thick tectum and foot layer with prominent unbranched columellae and an extremely thin endexine; pantoporate with thick tectum and foot layer with branched columellae enclosing pores and an endexine that is one to two layers thick; pantocolpate with thin tectum and foot layer with broad, short unbranched columellae and an inconspicuous endexine. All pollen types, however, have a spinulose and tubuliferous/punctate ektexine. Also, all the genera except three,Calandrinia H.B.K.,Montia L. andTalinum Adanson are stenopalynous. There is, however, no absolute correlation between pollen morphology and geographical distribution, although both the major centre of palynological diversity and the majority of all species with tricolpate grains occur in South America.     

A PALYNOLOGICAL INVESTIGATION OF THE GENUS TOURNEFORTIA (BORAGINACEAE)

The pollen morphology of 65 species of Tournefortia L. was examined by light, scanning, and transmission electron microscopy. Four distinct morphological types were found: Type I, grains subprolate with 3-colporate apertures alternating with three pseudocolpi and the ektexine psilate; Type II, grains subprolate, the poles expanded, 3-colporate with the ektexine psilate polarly and verrucate equatorially; Type III, grains spheroidal with three porate apertures and the ektexine clavate; Type IV, grains suboblate with 3–4 colporate apertures and the ektexine psilate to finely rugose. Type I was found in 46 species representing the most diverse group of tournefortias. Type II was found in 12 species from the Old and New Worlds representing two related groups. Type III was found in five closely related species from the American tropics. Type IV was found in two species from South America, but differences in both the pollen and sporophyte indicate that this grouping may be artificial. Pollen morphology does not support the separation of those species treated as Messerschmidia and confirms the close relationship of Tournefortia and Heliotropium. The striking morphological divergence of Tournefortia pollen raises the question of its adaptive significance.     

Erdtmanitheca portucalensis,a new pollen organ from the Early Cretaceous (Aptian–Albian) of Portugal with Eucommiidites-type pollen

A new lignitised, slightly compressed pollen organ, Erdtmanitheca portucalensis, with affinities to extinct Erdtmanithecales from the Early Cretaceous (Aptian–Albian) of Vale de Água (Lusitanian Basin, western Portugal), is described. The pollen organ is composed of loosely arranged microsporophylls radiating from a central core. The estimated number of microsporophylls is about 100–150. The microsporophylls are sessile and ellipsoidal to barrel-shaped with a flattened or slightly apically depression containing about ten narrow sporangia. The sporangia enclose abundant well-preserved pollen grains of Eucommiidites-type. Pollen grains found in situ are elliptical in equatorial outline, about 16.0–27.2 μm long and 11.9–16.4 μm wide. The main (distal) colpus is long with expanded rounded ends. It is flanked by two subsidiary colpi in an almost equatorial position. The surface of the pollen wall is psilate and occasionally punctate. The ektexine is composed of a distinct tectum, granular infratectal layer and a thin foot layer. The endexine is thick and laminar. The new Early Cretaceous Portuguese pollen-organ is similar in several respects to that of Erdtmanitheca texensis described from the Late Cretaceous of Texas, USA. The new fossil species further documents the importance of the Bennettitales-Erdtmanithecales-Gnetales group in the Early Cretaceous floras of Portugal extending the stratigraphic and geographical distribution of the genus with regard to systematic and phylogenetic significance of the Eucommiidites-producing plants that may have been co-occurring with the Early Cretaceous diversification of angiosperms. It is ascertained that perforate tectum occurs in pollen grains with a well-developed foot layer as well as in pollen grains in which a foot layer is poorly developed or lacking, and that pollen features do not support a separation of the Erdtmanithecales seeds and pollen organs.     

THE MORPHOLOGY OF THE EXINE IN NIGELLA (RANUNCULACEAE)

The pollen morphology of eight species of Nigella (Ranunculaceae) was examined by scanning and transmission electron microscopy. The exomorphology of all species was identical: 3-colpate, spinulose, and punctate, but thin sections revealed two structural patterns. The ektexine structure of Nigella integrifolia, consisting of thickened foot layer, columellae, and thin tectum, is typical for the family as well as the order Ranunculales in general. In contrast, the remaining seven species, N. arvensis, N. damascena, N. elata, N. hispanica, N. sativa, N. segetalis, and N. stellaris, have an ektexine with an additional unit, a horizontal layer with shorter columellae, placed between the foot layer and tectum. Of all genera examined in the Ranunculaceae, only Nigella had this unusual stratification. This difference in the exine structure would add support to the treatment of N. integrifolia as a monotypic genus, Komaroffia integrifolia (Regel) Lemos Pereira.     

A unique pollen wall mutation in the family Compositae: ultrastructure and genetics

During a routine screening of pollen fertility in the n = 2 chromosome race of Haplopappus gracilis, a spineless pollen wall mutation was discovered that renders the otherwise functional pollen grains completely unrecognizable as Compositae pollen. Normal Haplopappus pollen is characterized by an outer layer, the ektexine, consisting of large spines supported by a roof (tectum), which in turn is supported by collumellae that are joined basally. A large cavity (cavea) stretches from aperture to aperture and separates columellae bases from the final ektexine unit, the foot layer. The spines, tectum, columellae, and columellae bases are filled with perforations (internal foramina), while the foot layer is without them. Immediately underlying the foot layer is a thickened, lamellate, disrupted, internal foramina-free second exine layer, the endexine. In contrast, the mutant pollen ektexine is a jumble of components with randomly dispersed spines as the only clearly definable unit. The endexine layer is similar to the endexine in normal pollen. The mutation apparently disrupts only the organization of ektexine units, and mutant pollen appears to be without the caveae and foot layer characteristic of normal pollen. In genetic tests, the mutant allele is recessive. There is a simple Mendelian pattern of inheritance of the mutant gene, and its phenotype is under sporophytic control.     

POLLEN MORPHOLOGY AND DETAILED STRUCTURE OF FAMILY COMPOSITAE,TRIBE CICHORIEAE. II. SUBTRIBE MICROSERIDINAE

A survey of pollen morphology of 40 species representing eight genera of the primarily North American subtribe Microseridinae reveals seven of the eight genera to have caveate, echinolophate, tricolporate grains, Picrosia being the only taxon with echinate pollen. Sectioned grains reveal the exine to consist of an ektexine and endexine. The ektexine, composed of spines, columellae, and foot layer appears to be of two basic types, one with six or seven levels of horizontally anastomosing columellae which are reduced to a single columellar layer under the paraporal lacunae and the second, a bistratified ektexine not reduced to a single layer below the paraporal lacunae. Sectioned exines of Pyrrhopappus are unusual, having very large columellae fused to the foot layer below ridges and highly reduced columellae under lacunae. Endexine organization is similar in most of the genera. Exceptions to this are Pyrrhopappus and some species of Agoseris, which have an “endexine 2” layer. Subtribe Microseridinae is essentially stenopalynous. The pollen data support most of the relationships suggested by Stebbins in his classification. The genera Agoseris, Microseris, Nothocalais, and Phalacroseris seem to form a natural group while Krigia and Pyrrhopappus form another cohesive series. The position of Picrosia, as an advanced offshoot of Pyrrhopappus, is not supported by the pollen data.     

Ontogeny of the Calliandra – massulae (Mimosaceae: Ingeae), and the associated viscin body

Polyads, called also massulae, are common in the Mimosaceae. Within this family, only in Calliandra (s. l.) polyads show a remarkable morphological variation: 16-grained lens-shaped massulae in the neotropical Zapoteca (syn. Calliandra p.p.), and highly asymmetric eight-grained massulae in Calliandra (s. str.). As a further specialisation the massulae in Calliandra (s. str.) possess a sticky appendage called a viscin body. The form and ontogeny of this unique two-dimensional construction of the massula is of particular interest. In Calliandra (s. str.) the octad is normally the developmental product of the initiation stage, beginning with one pollen mother cell (PMC). In total, Calliandra (s. str.) possesses eight PMCs in each anther.The dicotyledons are characterised by the simultaneous type of cytokinesis, but wall formation in Calliandra (s. str.) during meiotic division is successive, as common in monocotyledons. The first wall divides the PMC diagonally, and during the tetrad period, two clear variants of tetrads are found. One shows the typical rhomboidal arrangement and the other forms two congruent symmetrical halves. The latter probably results from early fixed, quite inflexible walls. The cells of tetrad do not separate, and four successive mitotic divisions give rise to the eight-celled massula. The direction of growth of the PMC and the massula, the sequence of division, and the position of the walls all show a strict polarity. The normal number of eight cells in each massula is sometimes exceeded without loss of viability.Calliandra (s. str.) lacks a developed “Pollenkitt”, and its asymmetrical massula is combined with the viscin body, which is involved in pollination. This viscin body is located on a specialised pollen grain at the top of the massula. With the viscin body, Calliandra (s. str.) massulae have a mechanism for immediate and persistent attachment to different surfaces. SEM is used to understand the mechanisms of attachment in detail. Furthermore, the relation between pollinators and the massula shape is investigated. Massula transport and the role of the viscin body in pollen–stigma interaction are discussed as well. The stigma of Calliandra (s. str.) is papillate and in the receptive stage, it is characterised by acquisition of a copious exudate.Zapoteca (syn. Calliandra p.p.) massulae could be distinguished histochemically from those of Calliandra (s. str.) by the main components of the “Pollenkitt”. Histochemical and physical properties of the viscin body suggest a waxy nature, including lipids in combination with unsaturated fatty acids. Proteins are present in less amounts and polysaccharides and polyglucans are absent. These results are discussed in relation to analogous phenomena in other families.The term “apex cell” is introduced to indicate the specialisation of the tip-cell of the massula by ontogeny and polarity.     

On some peculiarities of sporoderm structure in members of the Cycadales and Ginkgoales

The pollen morphology and ultrastructure of Cycas micholitzii, C. simplicipinna, Cycandra profusa, Ceratozamia mexicana, and Ginkgo biloba are studied. Pollen germination is also studied in C. mexicana and G. biloba. Although dehydrated pollen grains appear monosulcate, the study of hydrated pollen shows that the aperture occupies nearly half of the pollen surface and represents a pore rather than a sulcus. In the Ginkgoales, the inaperturate ectexine is characterized by a thick solid tectum, infratectum of columella-like elements or large granules, and distinct foot layer. On the contrary, in the Cycadales, the ectexine consists of a thin tectum, alveolar infratectum, and poorly discernable foot layer. Members of the Ginkgoales have a distinct distal aperture, which is constituted by an intine, endexine, and thin ectexine. In the modern Cycadales, an ectexine is well developed throughout the pollen perimeter; in the supposed aperture region the ectexine is not reduced in thickness, although it is characterized by a thinner tectum and thinner walls of infratectal alveoli. In Cycandra profusa, no unequivocal aperture region has been found. Thickened regions were observed in the intine of both the Cycadales and Ginkgoales.     

Beschorneria yuccoides and Asimina triloba (L.) Dun: Examples for proximal polar germinating pollen in angiosperms

Beschorneria yuccoides (Agavaceae) microspores are arranged mostly in planar tetrads. Later on, the pollen grains of the tetrad usually fall apart, but sometimes remain loosely connected by ektexine elements. The ektexine consists of a tectum, of short columellae, and of a thin, discontinuous foot layer. An endexine is absent. The bilayered intine is without any additional thickening that would usually indicate an aperture region. From this point of view the pollen grain might be considered as omniaperturate. The pollen ornamentation is reticulate with wide lumina and robust, smooth muri.

The pollen grains show an indistinct sulcus characterised by a loose reticulate ornamentation. The sulcus is not exactly at the distal pole, but shifted towards the equator. No pollen tubes are formed regularly at the sulcus. Instead, pollen tubes are normally formed at the proximal pollen face. The proximal area, indicating a large germination field, is morphologically and functionally clearly an aperture (a germination zone); however, it does not represent a sulcus. The proximal face of all pollen grains appears as ornamented, with some exine lumps.

Asimina triloba (Annonaceae) pollen is shed in permanent planar or decussate tetrads. The distal sides are microreticulate to foveolate, and do not show an aperture; the psilate proximal sides are the germination areas of A. triloba.

The presence of apertures placed at the proximal pole was reported for distinct taxa of several angiosperm families. For Drosera, Dionaea (Droseraceae) and most probably for the diaperturate Cuphea species (Lythraceae) the existence of polar germination areas can be excluded. However, in some Annonaceae taxa with permanent tetrads (Annona cherimola, Asimina triloba) a situation similar to Beschorneria might be present, and indeed a proximal polar pollen tube is formed. Beschorneria yuccoides, Annona cherimola and Asimina triloba are unequivocal examples of angiosperm pollen with an exactly proximal aperture (germination area).     

Tapetal and parenchymatic anther tissues participate in polyad adhesive production in Calliandra brevipes (Leguminosae)

Calliandra brevipes Benth. is an American shrubby species largely used for ornamental purposes. Like all other Calliandra species it has heteromorphic pollen grains shed in ellipse-shaped, calymmate polyads and a unique mode of pollen presentation by producing a sticky substance called “pollen adhesive”. The present study aimed to investigate in detail the origin of polyad adhesive in C. brevipes. Serial microtome sections of anthers in various developmental stages were used and histochemical tests applied to detect the adhesive production sites and investigate the subcellular characteristics of the anther cells under transmission electron microscopy. The pollen adhesive in C. brevipes is not only produced by parenchymatic cells of the anther transversal septum, as it is described for Calliandra angustifolia, but parenchymatic cells and tapetal cells next to the polyad apical pollen grain also participate in the pollen adhesive production. The cytoplasm of the degenerating tapetum cells contains oleoplasts and fibrogranular material inside the vacuoles which mixes with the adhesive produced by adjacent parenchymatic cells and which therefore contributes to its composition. Vacuoles containing fibrogranular material are very similar to those found in tryphine producing tapetal cells, and the subcellular structures of parenchymatic and tapetal cells are similar to each other. The fact that the pollen adhesive becomes solid in contact with the environment is attributed to dehydration and the presence of the protein fibrogranular material and lipid substances since resin could not be found in its composition. It seems that the sites of pollen adhesive production in Calliandra may vary among its members. Studies of polyad adhesive production in the genus should be standardized in order to verify the information already available in the literature.     

Transition within the exine of Nothofagus Blume

Pollen grains with bulged areas on their proximal and distal faces were observed in some species of Nothofagus Blume in the light and electron microscopes. Pollen grains sectioned meridionally are distinctly transitionary in character in the individual strata within the exine of one pollen grain. The tectum in the apocolpia is considerably thinner than in the mesocolpia, The thickness and the character of the bacular layer in the mesocolpia differ greatly from those of the apocolpia. The foot layer, thick and always present in the mesocolpia, is entirely lacking in the apocolpia. The significant difference in the structure and thickness of the bacular layer, as well as the partial absence of the foot layer in one pollen grain, influence the cohesion between the individual strata of the exine in the apocolpia. The cohesion between the tectum and underlying, globular stratum in the central part of the apocolpia is poor, which facilitates the separation of the tectum and its bulging at that area.     

盖裂木属两种植物花粉形态观察

利用光学显微镜、扫描电镜和透射电镜观察了盖裂木属两种Talauma gloriensis和T.mexicana的花粉形态。花粉粒具远极单萌发沟,椭圆球形,外壁较光滑或略粗糙且具小穴状雕纹。在透射电镜下,花粉外壁可分为覆盖层、柱状层和基层,外壁-2明显,且厚度不均匀。在远极面萌发沟区域,外壁逐渐减薄,最后覆盖层和柱状层消失,仅残留基层。T.gloriensis的柱状层内部空间较小,多由颗粒组成,而T.mexicana柱状层中有发育较好的小柱,与覆盖层和基层连接。     

Pollen structure, tetrad cohesion and pollen-connecting threads in Pseuduvaria (Annonaceae)

The structure of the pollen of 42 species of Pseuduvaria (Annonaceae) is described. The pollen is consistently inaperturate, isopolar and radially symmetrical. Four basic patterns of exine sculpturing are identified: rugulate, verrucate, scabrate and psilate. The exine stratification of one representative species, P. macrocarpa , is shown to be entirely ectexinal. The ectexine consists of a discontinuous outer tectal layer, a columellar infratectal layer, and an inner lamellar foliated foot layer; the intine is very thin and fibrillar. The pollen is invariably released as acalymmate tetrads, in which the tectum is absent from the proximal walls. The individual pollen grains within the tetrads are connected by crosswall cohesion, involving both exine and intine; this form of cohesion has not hitherto been reported in the Annonaceae. In addition, pollen grains of neighbouring tetrads are connected in two different ways, viz. short exine connections and non-sporopollenin pollen-connecting threads. Neither of these cohesion mechanisms has previously been reported for the genus. The function of the various forms of cohesion between pollen grains and tetrads in Pseuduvaria is discussed as a mechanism to enhance the efficiency of pollination by enabling the fertilization of multiple ovules following a single pollinator visit.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 69−78.     

滇南风吹楠花粉形态观察

采用光镜、扫描电镜和透射电镜对滇南风吹楠的花粉形态进行观察.滇南风吹楠的花粉粒呈单粒存在,远极面观为椭圆形,近极面观大体为三角形,为不等极,两侧对称.花粉粒具一条远极单萌发沟;花粉大小为(15)19.90(21) μm×(20)22.50(25) μm.花粉粒外壁纹饰为网状,网脊平均宽度为0.29 μm;网眼形状不规则...     

Microsporogenesis and exine substructure in Uraria crinita (Fabaceae)

This paper intends to elucidate the anther wall development, pollen wall development and exine substructure of Uraria crinita (L.) Desv. ex DC. (Fabaceae). The undifferentiated anther is ovoid-shaped and tetrasporangiated. The anther wall development is basic type, which is comprised of an epidermis, an endothecium layer, two middle layers and a tapetum. Anther-tapetum is glandular type and the cells are uniseriate and uninucleate. Pollen grains are tricolporate and 2-celled at the time of shedding. Before protectum development begins, a glycocalyx layer is inserted against the callose, and the plasma membrane is invaginated, exclusive of the future apertures. Subsequently, the probacula are elongate under the protectum and arise basally from the plasma membrane. The foot layer and endexine formation are concomitant with the callosic wall dissolution. The foot layer is thin and interrupted, but the endexine is thick and continuous. The intine is initially in the vacuoled stage. The substructure in the tectum, bacula and endexine is the same as a rod-shaped in side view. It composed of the loop like striate elements.     

POLLEN MORPHOLOGY AND DETAILED STRUCTURE OF FAMILY COMPOSITAE,TRIBE CICHORIEAE. I. SUBTRIBE STEPHANOMERIINAE

A survey of pollen morphology in 20 species representing the 11 genera of the North American subtribe Stephanomeriinae by light, scanning electron, and transmission electron microscopy revealed 10 of the 11 genera to have echinate, tricolporate pollen grains, Lygodesmia being the only genus with echinolophate pollen. Sectioned exines of most of the species examined are similar, being composed of ektexine and endexine. The ektexine surface is composed of spines which typically have globose perforate bases. A cavus occurs as a separation between the basis (foot layer) and the columellae in all of the genera examined except Chaetadelpha. Pollen of the two species of Glyptopleura were found to be strikingly different in exomorphology. Pollen of the putatively self-fertile G. marginata has much shorter spines than the closely related G. setulosa. Atrichoseris, Anisocoma, Calycoseris, Glyptopleura, Pinaropappus, Prenanthella, and most species of Malacothrix have pollen which lack paraporal ridges. The remaining genera, Chaetadelpha, Lygodesmia, Rafinesquia, and Stephanomeria have well-developed ridges of fused spine bases around the apertures. Pollen characters, particularly those of the aperture region, have been found to be systematically useful in the subtribe, therefore acetolyzed material gives more useful information than untreated pollen.     

Exine ultrastructure of in situ peltasperm pollen from the Rhaetian of Germany and its implications

Morphology and exine ultrastructure of pollen grains of Triassic peltasperms have been studied for the first time. Pollen grains of Antevsia zeilleri from the Rhaetian of Germany are of the Cycadopites-type and monosulcate; the sculpturing is the same in the apertural and non-apertural areas. The proximal exine includes a row of lacunae covered by a solid, thick tectum and underlined by a foot layer. Pillars are hanging from the tectum between the lacunae. The exine is thinning to a homogeneous layer in the apertural region. The latter is bordered by thicker alveolate areas of the exine, in places resembling a saccus-like ultrastructure. The endexine includes white-line-centred lamellae. The exine ultrastructure is compared with that of pollen of Permian peltasperms. Although pollen types ascribed to Permian peltasperms are completely different in their general morphology, a transformation can be hypothesized by ultrastructural data from Permian Vesicaspora into Triassic Cycadopites extracted from pollen sacs of Antevsia. Comparison with Cycadopites of non-peltaspermalean (Ginkgoalean, Cycadophyte) and unknown affinities has been accomplished. The exine ultrastructure is distinctive enough to differentiate among peltaspermalean, cycadalean and bennettitalean Cycadopites; some ultrastructural features are shared with pollen of modern Ginkgo biloba. More ultrastructural data are needed as well as numerous sections of pollen grains are necessary to reveal original unchanged ultrastructure.     

Pollen morphology of JapaneseSymplocos (Symplocaceae)

The pollen morphology of all 23 Japanese species ofSymplocos (1 of subgenusEusymplocos, and 22 of subgenusHopea) was comprehensively studied using LM, SEM and TEM, and found to be classifiable into two types (Type I and II) primarily on the basis of wall structure. Type I, characterized by a thick tectum lacking a supratectal structure and reduced columellae, occurs in subgenusEusymplocos, while Type II, characterized by a thin tectum with a supratectal structure and generally distinct columellae, occurs in subgenusHopea. Resemblances in wall structure suggest a closer relationship of subgenusEusymplocos to subgenusMicrosymplocos as well as of subgenusHopea to subgenusEpigenia. This fact contradicts the earlier proposed infrageneric classification, and may require its revision. Within Type II, five subtypes are recognized primarily on the basis of sculpture combined with other pollen characters. Systematic value of sculpture (i.e., subtype), aperture morphology and “globules”, as well as certain species relationships based on those characters, are also discussed.