Cyanogenic glycosides and the systematics of the Flacourtiaceae

A survey of 682 accessions including 550 species and most genera of the Flacourtiaceae for cyclopentenoid cyanogenic glycosides showed the presence of only three compounds. These were found only in the tribes Berberidopsideae, Oncobeae, Pangieae and Banaraeae. The family is thus divided into cyanogenic and acyanogenic members. The former group possess compounds of similar structure to those of the Passifloraceae and have been considered primitive morphologically. It seems improbable that the Passifloraceae are derived from the acyanogenic, and putatively evolutionarily more advanced, group of Flacourtiaceae.     

Occurrence and biosynthesis of cyclopentenyl fatty acids in leaves and chloroplasts of flacourtiaceae

Cyclopentenyl fatty acids, the unusual fatty acids occurring naturally in certain Flacourtiaceae, have been detected for the first time in leaves of various plants belonging to the tribes Pangieae, Oncobeae and Flacourtieae. In leaves and chloroplasts of Caloncoba echinata (Oncobeae) cyclopentenyl fatty acids are synthesized from aspartate plus pyruvate or glutamate plus acetate. The biogenesis of the cyclopentene ring occurs from a C₇, compound, that may be formed by either pair of substrates.     

COMPARATIVE POLLEN MORPHOLOGY AND TAXONOMIC AFFINITIES IN CYCADALES

Scanning and transmission electron microscopy of pollen grains of 29 species, representing the ten extant genera of Cycadales, has provided valuable insight into their relationships. Pollen grains of these taxa are boat-shaped, monosulcate, and bilaterally symmetrical. They range from narrowly to widely elliptical or subcircular when viewed distally, and have an exine surface of psilate, foveolate, or fossulate. Pollen wall ultrastructure of Cycadales is typically tectate with alveolate∗∗∗spongy exine. The nexine is laminated in all genera. Nexine 1 (footlayer) is present in most species as a thin and often discontinuous layer. There is consistent variation in thickness of the sporoderm layers among the genera but relative uniformity within them. Pollen characteristics are well correlated with macro- and micromorphological features, chromosome numbers, geographical distribution, and postulated pollination mode. A close affinity between Encephalartos, Lepidozamia, and Macrozamia is recognized. Pollen characteristics of the genus Bowenia show some similarity with those of the latter group. Except for two species of Macrozamia which are narrowly elliptic, all of the genera have widely elliptic pollen and share a psilate exine surface and the thinnest sexine with nearly identical arrangement of alveoli. Pollen grains of the species in the genus Dioon exhibit a unique morphology but are more similar to Stangeria than they are to those of taxa in Zamiaceae. The circular outline of the grains and the foveolate exine surface are characters shared by these two genera, but several morphological features distinguish Dioon from Stangeria. Ceratozamia and Zamia share a widely elliptic shape, foveolate exine surface and nearly identical sexine, as well as morphological features and chromosome numbers. They differ from Microcycas in sexine thickness, gross morphology and chromosome numbers. The pollen grains of Cycas circinalis and C. revoluta differ in size and structure of the sexine from all other genera and from each other, substantiating their distinct subgeneric delimitations.     

Pollen Morphology of the Aceraceae

Pollen of 40 Acer taxa and one species of Dipteronia were examined by light, scanning and transmission electron microscopy. Pollen grains in both genera are tricolpate or tricolporate of prolate to nearly spheroidal shape. Based on sexine pattern, four major pollen types were recognized and include striate grains, rugulose grains, microreticulate grains, and granular grains. Although the family appears to be rather stenopalynous, several useful taxonomic variations occur.     

Species distinction in the “Potentilla pollen type” (Rosaceae) of NW Europe

Pollen grains of eight different species from the genera Comarum, Fragaria, Potentilla and Sibbaldia, usually considered as one type, the “Potentilla type”, were examined and morphological features making distinction possible are described     

An Ultrastructural Study of Pollen Wall Ontogeny in Silene Pendula

Pollen of 41 species representing all seven genera of the Neottieae were examined by scanning electron microscopy. Except for Lecanorchis, the genera of the Neottieae constitute a natural group based on pollen morphology. Pollen occurs as single grains in the primitive species and in tetrads in the other species. Most grains are monoaperturate, porate or tenuate, and the tetrads often have irregularly shaped grains. Exine structure varies from tectate-perforate to semitectate. Lecanorchis is anomalous among the Neottieae in that it has 0–5, sunken, relatively small pores. Pollen morphology of this genus indicates that it is probably more closely related to the Gastrodieae than the Neottieae. There are at least four basic phyletic units in the Orchidaceae: the Neottioideae, Apostasioideae, Cypripedioideae, and Epidendroideae. These groups are distinguished by the presence of monads in at least their more primitive members and by their unique pollen types.     

天麻抗真菌蛋白对木霉菌丝的作用位点

天麻抗真菌蛋白(Gastrodia Antifungal Protein,GAFP)能强烈抑制腐生真菌菌丝的生长,在天麻限制和防止蜜环菌［Armillariella mellea (Vahl. ex Fr.)Karst.］侵染球茎的防卫机制中起重要作用。本文报告GAFP抗菌机理研究的部分内容——GAFP对木霉菌丝的作用位点。用荧光试剂异硫氰酸荧光素(Fluorescein isothiocyanate,FITC)标记GAFP,试验表明,标记后的GAFP与未标记的GAFP对木霉菌丝生长均有抑制作用。在荧光显微镜下观察GAFP在木霉菌丝上的作用位点,发现被“标记GAFP”作用后的菌丝边缘有荧光,并主要集中在木霉菌丝的顶端和菌丝横隔处,表明GAFP对木霉的作用位点在菌丝的细胞壁上。     

大风子科13个种的花粉形态

利用光镜和扫描电镜对大风子科 9属 1 3个种的花粉形态进行了观察。花粉形状长球形或圆球形 ,除大风子属 (Hydnocarpus)萌发孔为三拟孔沟 ,其余均为三孔沟 ;外壁纹饰在不同属、同属不同种间表现出明显的多样化 ,基本上可分为粗网状、细网状、穿孔状、穴状4种类型。研究认为花粉形态对于该科与近缘科以及属下的划分具有一定的意义     

Studies on pollen morphology of selected species of Annonaceae from Thailand

The pollen morphology of 49 species and one variety, representing 18 genera of the family Annonaceae from Thailand, is described and illustrated based on observations using scanning electron microscopy (SEM). The pollen grains of Anaxagorea show double-spheres as a result of the intine extrusion. The palynological evidence confirms the close relationship of Dasymaschalon, Desmos and Asian Friesodielsia. Decussate tetrads in Goniothalamus and coexisting tetragonal, rhomboidal, T-shaped, tetrahedral and decussate tetrads in Mitrephora are reported. Pollen morphology is consistent within Huberantha, Marsypopetalum and Monoon, but is more diverse in Polyalthia sensu stricto Pollen unit, shape, size, ornamentation and aperture number reaffirm the great diversity among and within genera in Annonaceae.     

Lessingianthus (Vernonieae–Asteraceae): generic and infrageneric relationships based on pollen morphology

Pollen morphology of 31 species of Lessingianthus was investigated in order to evaluate the generic and infrageneric relationships of Lessingianthus and related genera. Acetolyzed pollen grains were measured, described and illustrated using light microscopy. Non‐acetolyzed pollen grains were investigated using scanning electron microscopy. Pollen grains of Lessingianthus are isopolar monads, suboblate, oblate spheroidal or prolate spheroidal, lophate (30, 29 and 27 lacunae), with small or large polar area, tricolporate. Pollen grains with 30 lacunae occur in the majority of the species examined, and show three apertural, six abapertural, twelve parapertural, six interapertural and three equatorial lacunae. Pollen grains with 29 lacunae occur in L. desertorum, L. simplex and L. virgulatus and are characterized by three apertural, six abapertural, twelve parapertural, six interapertural and two polar lacunae, and by absence of equatorial lacunae. Pollen grains with 27 lacunae occur in L. adenophyllus and L. durus and are characterized by three apertural, six abapertural, twelve parapertural and six interapertural lacunae, but lack polar and equatorial lacunae. Species of Lessingianthus subgen. Lessingianthus, with few exceptions, have pollen grains with type B lophate pattern, which differs mostly in shape. Pollen grains of Lessingianthus subgenus Oligocephalus share a very similar pattern of 29 lacunae with those of Chrysolaena, supporting recently proposed taxonomic changes. Pollen grains with 27 regular lacunae occur in Lessingianthus durus and L. adenophyllus, but the first differ from the latter by having cross muri enclosing the apertural lacuna (type G pollen).     

POLLEN MORPHOLOGY OF HAPLOPAPPUS AND RELATED GENERA (COMPOSITAE—ASTEREAE)

Pollen grains of Haplopappus and related genera in the subtribe Solidaginae from North and South America were examined by light and scanning electron microscopy. The grains are consistently tricolporate and echinate. Some genera can be distinguished by pollen size, spine length, and number of spine rows between colpi. Based on these characters, the divergence of Benitoa from other members of the subtribe, as indicated by its morphology and secondary chemistry, is supported. Additionally, the recently suggested absence of a close relationship between Pyrrocoma and Oonopsis is indicated by their contrasting pollen types. This study demonstrates the potential of pollen studies in distinguishing some taxonomic groups in the Astereae.     

POLLEN MORPHOLOGY AND SYSTEMATIC RELATIONSHIPS AMONG NEW WORLD SPECIES IN TRIBE ANTIRRHINEAE (SCROPHULARIACEAE)

The morphology of mature pollen grains among 12 New World genera in tribe Antirrhineae has been examined with light and scanning electron microscopy. Pollen from 29 American species have mean polar diam that range from 17 to 26 μm, have a tectate structure with perforate, microreticulate, or reticulate surface pattern, and are subspheroidal to prolate, and trizonocolporate with fusiform or narrowly oblong colpi that are free or occasionally fused at the poles. Among the genera, pollen size is positively associated with style length but not haploid chromosome number. Three major morphological categories are recognized based on grain shape, exine structural pattern, and colpus shape. Two of these morphotypes each characterize individual genera (Mohavea, Linaria). The other morphological category includes ten New World genera and has been divided into three subcategories based on variation in lumina diam and intermittent occurrence of fused colpi. Only Antirrhinum and Pseudorontium have species or populations with pollen in more than one subcategory. Concordance of morphological, anatomical, chromosomal, and palynological data suggests that Linaria and Mohavea are best placed in separate subtribes from other native American genera. Compared to Old World taxa in tribe Antirrhineae, the most common pollen type (subspheroidal, microreticulate, apocolpate, fusiform colpi) may be the most primitive. Pollen grains with fused colpi (Antirrhinum p.p., Pseudorontium) and perforate (Mohavea) or reticulate (Holmgrenanthe) structural patterns probably represent derived types.     

天仙子族(茄科)的花粉形态补充研究及其系统学意义

在扫描电镜下研究了茄科天仙子族7属及颠茄属、茄参属和枸杞属3属共10属23种植物的花粉形态学特征。结果表明:天仙子族的花粉粒形状为球形、近球形、扁球形和长球形;萌发孔类型有无萌发孔、不规则的拟孔、3沟、4沟、3～4沟、散沟和3孔沟;外壁纹饰为小刺状、瘤状、各式条纹状、条纹-穴状、条纹-网状、皱波状、细网状和网状。沟膜近光滑、具小颗粒、具小刺状突起或具瘤状突起。各属植物的花粉形态在萌发孔的有无、萌发孔的类型和外壁纹饰等方面有较大的差异,可以作为探讨属间分类和系统关系的重要依据。天仙子族植物花粉萌发孔的演化趋势为:无萌发孔→3、4沟→3孔沟。无萌发孔的山莨菪属是原始类群,三孔沟的马尿泡和天仙子等属是进化类群。还讨论了与前人研究结果不同之处和可能的原因。     

POLLEN MORPHOLOGY OF THE EUCHARIDEAE (AMARYLLIDACEAE)

Eucharis, Caliphruria, and Urceolina form a monophyletic group of petiolate-leaved, Neotropical Amaryllidaceae ecologically specialized to the understory of primary tropical rain forest below 2,000 m elevation. Pollen morphology of the three genera is surveyed. Pollen grains of all species of Eucharis, Caliphruria, and Urceolina are boat-shaped elliptic, monosulcate, heteropolar, and bilateral in symmetry. Exine sculpturing is semitectate-columellate and reticulate in all species examined. A transformation series in reticulum coarseness and pollen grain size is described. The large pollen grain with coarse reticulum of most Eucharis species is considered ancestral. The fine reticulation of Caliphruria is considered derived and the exine morphology of Urceolina is intermediate. Both of these genera have medium-sized pollen grains. Exine dimorphism common to all Urceolina, but rare in Eucharis and Caliphruria, may be symplesiomorphous among those taxa exhibiting this morphology. The three genera are largely uniform in pollen grain ultrastructure, with completely ektexinous exines. Pollen grain size in Eucharis is not closely correlated with style length. Several wide-ranging species show considerable intraspecific variation in pollen size. Parallelisms in pollen grain evolution among related tribes of Neotropical Amaryllidaceae are discussed.     

Contributions to the pollen morphology and taxonomy of the Liliaceae

Pollen of 34 species from 7 genera of the Liliaceae were examined by LM and SEM with respect to the taxonomy of the family. Detailed pollen­morphological characteristics are given for all genera in the family on the basis of the results presented here together with data from the literature. The genera Tulipa and Lilium are heterogeneous in both aperture type and exine ornamentation. Pollen of Tulipa is monosulcate, 3-aperturate or inaperturate, with a microreticulate-striate, reticulate-implecto-striate, scabrate, perforate-rugulate, perforate-striate exine surface. Pollen of Lilium is monosulcate and 3-porate with a macroreticulate exine. The other genera are homogeneous in possessing of single longitudinal aperture (type monosulcate). The pattern of exine ornamentation and the structure of the aperture and its membrane are peculiar features for species and genera. Pollen of Erythronium and Tulipa are occasionally operculate, while in other representatives of the Liliaceae an operculum is lacking. Pollen morphological data support the division of the family into 3 tribes, namely Lloydieae, Lilieae, and Tulipeae.     

Studies in Montia L. and Claytonia L. and Allied Genera

The pollen morphology of several genera in Portulacaceae is described. Particular attention has been paid to the genera of the subfamily Montioideae, as a stage of continued monographical studies. Among genera especially dealt with are Claytonia, Montia, Crunocallis, Naiocrene, Neopaxia, Mona, Maxia, Limnalsine, and Montiastrum. In the taxonomical treatment of these genera the pollen morphology has proved to afford many important additional characters.

The pollen grains of Claytonia are distinguished from those of the remainder in being 3-colpate. The grains of the Claytonia-type have many similarities with those of Lewisia, a genus of the subfamily Portulacoideae. The other genera of Montioideae have pantocolpate pollen grains. Among these genera several different pollen types are distinguished, chiefly with regard to the sexine structures and the aperture membranes. The Montiastrum-type is especially interesting, with tholate grains, a particular pollen type not met with in any other genus in the family. The pollen morphology of some genera in the Portulacoideae is also treated. In some species in Calandrina and Talinum pantotreme pollen grains are observed with apertures transitional between pori and colpi. The apertures of the pantotreme grains are arranged in characteristic patterns.

Particular attention has been given to the variation of the pollen morphological characters. This variation has been examined with regard to the differences between different populations of the same species as well as between different species. The greatest variation has been observed in the shape and size of the grains. The structure and sculpture and thickness of the sexine and the aperture membranes are less variable. Some polyploid taxa are connected with the occurrence of pollen grains with divergent and varying aperture numbers.

In a survey of the genera the taxonomical results of the investigation are presented with particular regard to the pollen morphology. The new genus, Maxia Ö. Nilss., is described. One new species, Montia clara Ö. Nilss., is described and some new combinations are made.

Pollen morphological diagnoses are given for 46 different taxa. The aperture conditions for 96 different species are presented.     

Ultrastructure and Germination Percentage of Crocus biflorus Miller subsp. biflorus (Iridaceae) Pollen

Pollen of Crocus biflorus Miller subsp. biflorus from natural habitats of Tusculum (Frascati, near Rome, Italy) has been studied in order to compare its structure and physiology to pollen of other Crocus species belonging to the Crocus sativus group. Mature pollen grains are rounded, 60 μm in diameter, in-aperturate (but with surface incisions where exine is lacking). DAPI staining reveals a spindle-shaped generative nucleus which is intensely fluorescent, and vegetative nucleus which is less fluorescent, and is elongated with numerous lobes. At anthesis the pollen is bicellular, but about 2% of tricellular grains occur among the pollen grains released from the anthers as well as on both naturally or handpollinated stigmas. Pollen germination is low in vitro, but higher in vivo. The pollen tubes are of normal shape. An electron-dense surface coat is sometimes visible on the exine, which in many cases, is detached from the exine. The vegetative cytoplasm is very rich in glycolipid bodies surrounded by endoplasmic reticulum. The generative cell has a lobed cell wall and is surrounded by the vegetative nucleus.     

A PERMINERALIZED FLOWER FROM THE MIDDLE EOCENE OF BRITISH COLUMBIA

A permineralized flower bud, two stamen clusters and one isolated stamen of similar morphology have been found in the black cherts of the Middle Eocene Allenby Formation of Princeton, British Columbia. Specimens were studied using a modified cellulose acetate peel technique and hydrofluoric acid. The single flower specimen, 4.5 mm long and 4.0 mm in diameter, represents half of a relatively mature bud of a bisexual flower with a superior ovary. The two-loculate pistil is 2.5 mm long with a solid style and a lobed stigmatic surface. No ovules have been observed in attachment. Twenty-two to 24 stamens are borne in three whorls or a tight helix. Pollen sacs of the anther are elongate with a thin connective while filaments are laminar. Anther walls contain rectangular cells with dark contents that also can be identified in isolated stamens or stamen clusters. Abundant stephanocolpate (pentacolpate), psilate pollen grains 20 μm in diameter have been isolated and examined using scanning and transmission electron microscopy. Grains are tectate, columellate with a broad foot layer that thins near the apertures, and an endexine of small platelets. The remains of four petals are surrounded by one large sepal, suggesting two in the whole flower. Morphological features of this flower are comparable to taxa of the Flacourtiaceae and Papaveraceae, but show closest similarities to the Eschscholziaeae of the Papaveraceae. Difficulties with reconciling the placement of this flower in the Eschscholziaeae and the known environment of deposition of the Princeton chert are discussed. The fossil material represents a new angiospermous taxon: Princetonia allenbyensis Stockey gen. et sp. nov., family Incertae sedis.     

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.