SEED-COAT MORPHOLOGY AND ANATOMY IN COLLOMIA (POLEMONIACEAE)

Seed-coat morphology of 14 species of Collomia (Polemoniaceae) was examined with light microscopy and scanning electron microscopy. Two seed types were observed based on surface sulpturing: Type 1—hexagonal epidermal cells forming a shallow reticulum with well-defined cell boundaries; Type 2—longitudinally ridged and irregularly arranged crater-like depressions with inconspicuous cell boundaries. Only two species, C. debilis and C. larsenii of sect. Collomiastrum have seed-coat Type 1. Seed-coat Type 2 is characteristic of all species of sect. Collomia, sect. Courtoisia, and C. mazama, C. rawsoniana of sect. Collomiastrum. The present investigation reveals a fairly homogeneous seed-coat pattern in the genus and does not offer significant information for realignment of infrageneric classification. Anatomical studies with light microscopy show that a mucilaginous seed coat develops from the outermost layer of integument in which each epidermal cell develops spiral secondary wall thickenings. Mucilaginous seeds of most Collomia species probably provide adaptive significance in that adherence of seeds to ground prohibits further dispersal to unfavorable habitats, or epizoochoric dispersal.     

The conserved nature and taxonomic utility of pollen morphology in Cantua (Polemoniaceae)

Pollen exine morphology of nine of the ten species of Cantua (Polemoniaceae) is examined using light and scanning electron microscopy. A total of 28 specimens of C. bicolor, C. buxifolia, C. candelilla, C. cuzcoensis, C. flexuosa, C. pyrifolia, C. quercifolia, C. volcanica, and an as yet undescribed species (Cantua sp. nov.) are examined using either fresh or herbarium material. Pollen grains are found to be spheroidal, pantoporate, and quite large; mean diameter varies from 62 to 87?μm. Mean number of pores varies from 4.5 to 21.2 and mean pore size varies from 4.86 to 12.40?μm. Pollen grains of all species have insulate semitectate sexines. This feature distinguishes the pollen of Cantua species from the remainder of the Polemoniaceae. Insulae are evenly distributed over the surface of the pollen grain, with the exception of C. flexuosa and occasionally C. buxifolia, where insulae are more sparsely and haphazardly distributed. The majority of the species examined have irregularly shaped tectal insulae, with the exception of the large rounded insulae in C. quercifolia and the elongated narrow insulae in C. volcanica. Cantua quercifolia and C. volcanica have supratectal verrucae, a possible synapomorphy. In comparison to close relatives, the pollen grains of Cantua are evolutionarily conserved, and show little variation among species.     

Variation of pollen morphology, and its implications in the phylogeny of Clematis (Ranunculaceae)

Clematis s.l. (including Archiclematis and Naravelia) is a genus of approximately 300 species with cosmopolitan distribution. The diversity of its pollen was surveyed in 162 taxa belonging to all infrageneric groups of Clematis s.l. Pollen morphology was investigated by use of scanning electron microscopy to identify useful characters, test taxonomic and systematic hypotheses, and elucidate pollen character evolution on the basis of the molecular phylogeny. Clematis pollen is small to medium (14.8–32.1?μm?×?14.2–28.7?μm), oblate to prolate (P/E?=?0.9–1.4) in shape. The apertures may be tricolpate and pantoporate sometimes with 4-zonocolpate and pantocolpate pollen grains as transitional forms. The tricolpate pollen grains are predominant and occur in all the sections of the genus, whereas pantoporate pollen grains can be found in sect. Tubulosae, sect. Viorna, sect. Viticella, and Naravelia only. Phylogenetic mapping of aperture types reveals that the pantoporate pollen type may be the apomorphy in the genus and evolved several times. The surface ornamentation in all taxa studied is similar and characterized by microechinae evenly distributed on the microperforate tectum. The size and density of spinules on the tectum vary greatly but successive in the whole genus. According to the character syndromes of the ornamentation, separating sect. Brachiata from sect. Meclatis is supported. Though pollen morphology may contribute to investigation of problematic taxa, the taxonomic value of pollen morphology is limited at the species level.     

Pollen Morphology of Polemoniaceae in Relation to Systematics and Pollination Systems: Scanning Electron Microscopy

Representative pollen grains of each genus and section of the family Polemoniaceae were examined with scanning electron microscopy. Exine pattern diversity within the family is discussed in relation to pollination biology. Pollen data support some previously recognized relationships within the family; in other instances the use of pollen morphology suggests the institution of new associations. The value of pollen morphology as an index to possible phylogenetic interpretations within the Polemoniaceae is discussed.     

POLLEN MORPHOLOGY OF THE DILLENIACEAE AND ACTINIDIACEAE

Pollen of 53 species of Dilleniaceae and Actinidiaceae was examined by light microscopy, scanning electron microscopy, and a selected group in transmission electron microscopy. Dilleniaceae pollen ranges from tricolpate, tricolporate, tetracolpate, and incipiently inaperturate. Tricolpate types occur only among the Old World subfamily Dillenioideae and the compound aperturate (3-colporate) condition is restricted to the subfamily Tetraceroideae. Within the Dilleniaceae the tricolpate pollen type with elongated apertures is considered primitive, having given rise to the 3-colporate and 4-colpate conditions. The striking pollen dimorphism in the Neotropical species of Tetracera, all of which are androdioecious, is documented; however, in contrast to previous reports, pollen from bisexual flowers appears to be incipiently inaperturate and not pantoporate. The inaperturate condition is interpretated as an early stage in the evolution of outcrossing. Pollen morphology does not support a close relationship between Dilleniaceae and Actinidiaceae. Pollen morphological differences that can be noted between these families are: tectum complete and predominantly psilate or psilate-granular in Actinidiaceae, tectum incomplete, punctate to reticulate in Dilleniaceae; an equatorial bridge of ektexine over the endoaperture usually present in Actinidiaceae, absent in Dilleniaceae; columellae reduced in Actinidiaceae, columellae usually well-developed in Dilleniaceae. Pollen morphology does not argue against a close relationship between Actinidiaceae and Theaceae.     

POLLEN MORPHOLOGY AND SYSTEMATICS OF SIPHONOGLOSSA SENSU LATO (ACANTHACEAE)

Pollen morphology of 15 species of Siphonoglossa and of two closely related groups was investigated. Two tribal-specific pollen types are found within Siphonoglossa sensu lato suggesting that the genus is artificial, composed of taxa belonging in several genera among two tribes (subtribes sensu Bremekamp) of Acanthaceae. Five taxa currently included in an informal subgeneric category of Siphonoglossa have tricolporate, prolate pollen (termed Type I) that is characteristic of Odontonemeae (= Odontoneminae, Justicieae). Pollen of the remaining taxa, belonging in two formal sections of the genus, are mostly 2-porate, bilateral (Type II) with a sexine sculpturing characteristic of Justicieae (= Justiciinae). Pollen of section Siphonoglossa is rather uniform, 2-porate, bilateral with lolongate pores, and seem to delimit a natural group. Taxa of section Pentaloba have a more heterogeneous pollen morphology, mostly 2-porate, bilateral with lalongate pores. Controversial aspects of the interpretation of pollen morphology in Justiciinae are presented and their relevance to this study are examined. Hypothetical trends in the evolution of pollen of Justiciinae are discussed and the application of pollen morphology to taxonomy of the genus is presented, including a recommendation for narrowing the generic concept of Siphonoglossa to the taxa of the type section.     

Pollen types in Southern New World Convolvulaceae and their taxonomic significance

Pollen morphology from 143 collections representing 11 genera and 75 species of native South American Convolvulaceae was analyzed with LM and SEM. Exine structure and sculpture allow to distinguish three main types, in two of these types some subtypes were recognized. 1) Tectate, microechinate-perforate exine, with ramified columellae. On the basis of apertures three subtypes were distinguished: tricolpate in Aniseia, Bonamia, Convolvulus, Cressa, Dichondra, Merremia and Jacquemontia blanchetii; penta-hexacolpate in Merremia umbellata; and pantoporate with elliptic and circular pores, in Calystegia. 2) Tectate, microechinate-perforate exine with microspines and single columellae in concordant pattern, relates pantocolpate pollen of Jacquemontia and Evolvulus. From pollen data generic status of J. blanchetii should be considered. 3) Semitectate, echinate or gemmate, microechinate-microreticulate exine with single columellae is exclusive of pantoporate pollen of Ipomoea. Four subtypes were recognized in this genera, which are discussed in relation to Austins infrageneric classification.     

毛茛叶报春组一存疑种花粉形态的多样性研究

对分布于浙江西北部的毛茛叶报春组(sect. Ranunculoides)一存疑种5个居群共50个植株的花粉形态进行了研究观察。结果表明该存疑种的花粉形态特征在种下具高度多样化,根据萌发孔类型、数量及组成的不同,其花粉可划分为多沟型、沟多孔少型、孔多沟少型、散孔型和环沟型5种类型;而且居群间花粉的大小及花粉类型的组成也存在较大的差异;此外,同一个植株或同一个花粉囊的花粉也可能具有多种类型的花粉。本文进一步证明了花粉形态特征在种内可能存在多样化的现象。花粉形态特征支持该存疑种为一个独立的新物种,它很可能是由具多沟型和散孔型花粉的亲本杂交进化而来。     

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.     

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.     

Die pollenmorphologie der afrikanischen buxus- und notobuxus-arten (buxaceae) und ihre systematische bedeutung

Pollen grains of 8 African species of Buxus and Notobuxus were examined by light and scanning electron microscopy. Three pollen types are recognized based on the exine sculpture and the evolutionary trends of the pollen characters are discussed. Pollen morphology shows the existence of three major systematic groups. These results support the previous classification of an African section Probuxus with two subsections and speak in favor of the generic rank of the Notobuxus species. Together with anatomical and taxonomical data pollen morphology and its evolutionary trends lend support to the suggestions that the centre of origin of the genus Buxus might have been in Africa, while secondary centres of evolution have developed in the neotropical and Eastasian region.     

Using palynomorphological characteristics for the identification of species of Alsinoideae (Caryophyllaceae): a systematic approach

Palynological characters of 18 species belonging to seven genera of the traditional subfamily Alsinoideae including Arenaria, Cerastium, Eremogone, Lepyrodiclis, Minuartia, Sabulina and Stellaria were studied in detail using light and scanning electron microscopy. Pollen grains of subfamily Alsinoideae are subspheroidal or prolate, pantoporate and 20.04 to 51.4 µm in size, prominent and sunken apertures uniformly distributed on the pollen surface. Two types of pollen grain ornamentation were observed, i.e. microechinate-punctate or microechinate-perforate. Echini are present on the surface of the pollen of all investigated species with medium, dense, or sparse echinodensity. These species exhibit variation in polar view, equatorial diameter, number of apertures, exine thickness, diameter of pore, appendages per pore, pore ornamentation, echini arrangement, echinidensity and shape of pollen. Based on qualitative characters, a dichotomous key has been developed for quick and easy identification. The present investigation contributes to the systematic approach using palynological characteristics and correct identification of species for members of subfamily Alsinoideae (Caryophyllaceae).     

Pollen morphology of Quercus sect. Ilex and its relevance for fossil pollen identification in southwest China

Pollen grains of 16 modern species of Quercus were examined by scanning electron microscopy (SEM) and light microscopy (LM). The focus of this investigation was on a small group (c. eight species) of alpine, sclerophyllous oaks that may form a monophyletic group within sect. Ilex. The data were combined with published data for Polar axis (P) and Equatorial diameter (E) for more than 80 species. Based on pollen morphology Quercus pollen grains were divided into three types: (1) The Cyclobalanopsis type is smallest (generally < 23 μm) in size, with P/E ratios of approximately 1.08 and a psilate or fine-grained surface; (2) Quercus sect. Ilex type is 23–29 μm, the P/E ratio is approximately 1.24 (prolate) and it has a rugulate pollen surface; (3) the Quercus sect. Quercus type is generally > 29 μm in size, has a P/E ratio of approximately 1.04, and a clearly verrucate pollen surface. Based on a comparison with modern pollen size and ornamentation, fossil pollen grains of the Quaternary Qinghai Lake core can be assigned to the Chinese southwest mountain oak group of Quercus sect. Ilex (in particular Quercus semecarpifolia). In addition, we show that the pollen percentages of Quercus rapidly increased to the highest level during the glacial period. Using SEM for the identification of fossil Quercus pollen grains is essential to ensure the accuracy of differentiating evergreen Quercus types (sect. Ilex versus sect. Cyclobalanopsis) during the last glacial period in southwest China.     

Pollen morphology of Chamaebuxus (DC.) Schb., Chodatia Paiva and Rhinotropis (Blake) Paiva (Polygala L., Polygalaceae)

Polygala L. is a large and highly diverse genus with complex taxonomy, but pollen morphological information for this taxon is scarce. In the present study, pollen characters have been used to assess the taxonomic delimitation and phylogenetic relationships of three newly established subgenera of Polygala: Chamaebuxus, Chodatia and Rhinotropis (sensu Paiva). The pollen morphology of 22 species has been examined using light microscopy and scanning electron microscopy of acetolysed material. The pollen of 15 of the species is examined for the first time. The pollen grains are isopolar, radially symmetrical, tectate and, typically, polyzonocolporate with numerous colpi running parallel to the polar axis, and an endocingulum around the equator. Two pollen types can be distinguished: Type I, which includes species belonging to Rhinotropis, and Type II, which includes species from Chamaebuxus and Chodatia. The two pollen types are described and the pollen of the three studied subgenera is illustrated. Despite the low infrageneric morphological diversity observed within the genus Polygala, quantitative characters of pollen grains support the current classification of the subgenera Chamaebuxus, Chodatia and Rhinotropis, and reveal a closer relationship between the first two taxa. Pollen characters are shown to be a useful and informative tool for assessing taxonomic position and phylogenetic relationships within Polygalaceae, especially at higher taxonomic levels.     

TAXONOMIC IMPLICATIONS OF EXTERNAL POLLEN MORPHOLOGY TO VERNONIA (COMPOSITAE) IN THE WEST INDIES

External pollen morphology of 39 species of West Indian Vernonias was examined by light and scanning electron microscopy in conjunction with a systematic revision of these species. There were three distinct types of pollen: Type A: subechinolophate, tricolporate grains with prominent spines; Type B: echinolophate, tricolporate with expanded germinal furrows and coincident polar muri; Type C: echinolophate, tricolporate grains with prominent polar lacunae. Pollen grains intermediate between the major types were found in several species. These same species had very distinct and atypical megamorphologies. In general, pollen types were found to correlate well with classification based on megamorphological characters, particularly at the infrageneric level, and to provide confirmation of subsectional assignments in the genus.     

Pollen Morphology in the Order Centrospermae

Pollen of 190 species from 16 families has been examined by light and scanning electron microscopy. Three basic pollen types were found: 3-colpate, pantoporate, and pantocolpate, all with a spinulose and tubuliferous/punctate ektexine. The palynological data emphasize the close relationship of the betalain families, and support their association with the anthocyanin families. Caryophyllaceae and Molluginaceae. Pollen morphology reinforces the placement of the Cactaceae and Didiereaceae in the order, and would support the inclusion of Dysphania in the Chenopodiaceae. The pollen grains of the Achatocarpaceae, Bataceae, Gyrostemonaceae and Theligonaceae, none of which had the spinulose and tubuliferous/punctate ektexine, had no counterparts in the remaining taxa examined. Thus, the evidence from palynology does not support their inclusion in the Centrospermae and indicates that their placement should be re-examined.     

Studies on Pollen Morphology of Pulsatilla Mill.

Pollen grains of 18 species of Pulsatilla in Ranunculaceae distributed in Asia and Europe were examined by LM and SEM, and exine ultrastructure of tricolpate pollen grains of P. chinensis and of pantoporate pollen grains of P. campanella was examined by TEM. Pulsatilla pollen is divided into four major types based on the aperture character, i.e. tricolpate, di- and tricolpate, pantocolpate and pantoporate. The revolutionary trend of pollen types is as follows: tricolpate→pantocolpate→pantoporate. Surface spinulate and perforate. According to density and size of sptnulae and distribution of perforation, the pollen grains of the genus can be divided into two groups. Thin sections of P. chinensis and P. campanella show endexine thickened at colpi and ora. Ektexine consists of a foot layer, a collumellae layer and a continuous, perforate tectum. The columallae layer is thicker than foot layer and tectum. Pollen morphology of Pulsatilla is similar to that of Anemone, but different in the distribution of spinules and perforation. Pollen information supports Wang’s view about systematic arrangment of species of Pulsatilla in China.     

Pollen morphology and localization of Ni in some Ni-hyperaccumulator taxa of Alyssum L. (Brassicaceae)

Pollen morphology of seven Alyssum L. taxa growing on serpentine soils in different places in the European Mediterranean macrobioclimate territory were studied, described and compared. Cluster analysis was performed to show similarity between species and their populations. The shape of the pollen grains varies among the species and among the grains within the same anther. The pollen grains are 3-colpate, prolate, with long and narrow colpi reaching the poles. The ornamentation of the exine varies from micro-reticulate to reticulate between the species. Pollen sterility/fertility was also calculated. The highest percentage of sterile pollen (73.76%) was calculated for Alyssum murale subsp. murale and the lowest (9.54%) for A. bertolonii subsp. bertolonii. All species are representatives of sect. Odontarrhena (C.A. Meyer) Koch well known as Ni-hyperaccumulators. Nickel and other elements present in pollen and stamen were studied by inductively coupled plasma-mass spectrometry. The stamen parts of all species were micromorphologically analyzed by scanning electron microscopy coupled to an energy-dispersive X-ray probe. Accumulation of Ni was detected in the stamens of all studied species and rarely in the pollen grains. The distribution patterns of Ni were similar among the species examined.     

Pollen morphology of some <Emphasis Type="Italic">Paronychia</Emphasis> species (Caryophyllaceae) from Turkey

The 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.     

POLLEN MORPHOLOGY OF THE LENNOACEAE

Drugg , Warren S. (California Res. Corp., La Habra.) Pollen morphology of the Lennoaceae. Amer. Jour. Bot. 49(10): 1027–1032. Illus. 1962.—The family Lennoaceae contains 3 genera: Pholisma, Lennoa, and Ammobroma. The pollen of Pholisma is 4-colporate with less common 3- and 5-colporate grains. Lennoa pollen is 3-colporate with rare 4-colporate examples. All Ammobroma pollen is 3-colporate. Pollen of both Lennoa and Ammobroma exhibits sexine thinning in the mesocolpia with resultant depressions. This feature is lacking in Pholisma. Sculpture is reticulate-simplibaculate on pollen of Lennoa and Pholisma, and reticulate-duplibaculate on pollen of Ammobroma. Pollen morphology supports placement of Lennoaceae in the Polemoniales near the Boraginaceae and Hydrophyllaceae.