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Abstract: Scanning electron microscope (SEM) is necessary to demonstrate presence or absence of pit membranes in possible perforations or the type of pit membrane remnants in perforations in vessel element end-walls of angiosperms, but it was unconfirmed and questionable whether pit membrane absence in pits was affected by the processing and handling before SEM observations. To solve this question, the secondary xylem of four woody species from primitive angiosperms, Illicium henryi Diels. (Illiciaceae), Schisandra rubriflora (Franch.) Rehd. et Wils. (Schisandraceae), Tetracentron sinensis Oliv. and Trochodendron aralioides Sieb. & Zucc. (Trochodendraceae) was chosen and the following techniques were used: (1) fresh materials were examined in low-vacuum with ESEM. (2) Air-dried materials were examined both in low- and high-vacuum with ESEM. (3) Fresh materials fixed in several different fixatives were observed in low-vacuum, respectively. (4) Smooth surface of the material by paraffin section methods was examined in high-vacuum. (5) Materials treated by Jeffrey''s Fluid were observed in high-vacuum. Pit membranes and remnants in perforations of fresh material were little different from that of treated materials. Absence of the pit membrane in perforations (pits) in the end-wall was not attributed to the processing and handling. Information of pit membranes and remnants in perforations in end-wall based on the SEM observation might be validly claimed. [Copyright &y& Elsevier]

Abstract: Floral development and floral phyllotaxis in species of Adonis, Callianthemum, and Trollius (Ranunculaceae) were studied with scanning electron microscopy. The floral organs are initiated in spiral sequence and the flowers have spiral phyllotaxis. The sepal primordia are broad, crescent-shaped, and truncate, but those of petals, stamens, and carpels are rather hemispherical. A relatively long plastochron appears to be present between the last sepal and the first petal as compared with the short and equal plastochrones of all subsequent floral organs. Maturation of the stamens within the androecium appears to be centripetal. The carpels have a short ascidiate zone. Placentation is uniformly lateral, even in Adonis and Callianthemum, which have only one fertile ovule per carpel (versus median in other genera of Ranunculoideae with a single fertile ovule). In Adonis and Callianthemum at the tip of the carpel the ventral slit is gaping and the stigma is broadly exposed, whereas in Trollius the stigma is narrower and more pronouncedly decurrent along the ventral slit. The petals in Callianthemum and Trollius are more conspicuously delayed in development than those in Adonis as compared with sepals and stamens. A short carpel stipe is formed early in Callianthemum but later in Adonis and Trollius. In Trollius farreri (commonly having only five carpels in contrast to other species of Trollius) the carpels form a single (spiral) series. Thus floral development is similar in all three genera and, at a lower level, Adonis and Callianthemum are especially close but have different autapomorphies, which reflects the current classification of the genera. [Copyright &y& Elsevier]

• Floral structures are variable in Eranthis. • The stamen number is the main contributor to structural variation. • Morphological variation in Eranthis mainly occurred in petals. • Both sepal and petal numbers fit the modified error function. There is wide diversity in flower structure and pattern in nature. The number and morphological variation of flower organs in Eranthis of the family Ranunculaceae is high, but the pattern of flower structure variation in this genus is unclear. In this study, the morphological and numerical variation in organs of Eranthis stellata Maxim. and Eranthis lobulata W. T. Wang were observed with stereomicroscopy and scanning electron microscopy, and the patterns of variation were summarized statistically. The results showed the following: (1) The structural patterns of the two species of Eranthis were not stable. There were 232 flower structural patterns among 300 individuals of E. stellata and 55 among 100 individuals of E. lobulata. The number of floral organs in E. lobulata was significantly less than that in E. stellata. (2) The morphological variation in flower organs in Eranthis mainly occurred in petals, especially in the upper lip, pseudonectaries and lower lip, e.g., the number of lobes, and pseudonectaries and inconsistency in the upper lip edge. (3) The coefficient of variation (CV) of flower organs was greater than 20%, with some values close to 40%, which indicates that the number of floral organs of the two species differ substantially, and that the number of floral organs was extremely unstable. The range in stamen number was the largest while that in sepal number was the smallest, and this fluctuation might be caused by the spiral phyllotaxis of floral organs. [ABSTRACT FROM AUTHOR]

• Petal spurs in Aquilegia kansuensis, A. rockii, A. semicalcarata and A. ecalcarata have different lengths and nectary structures. • Early petal development is similar, and petals undergo delayed development, resulting in different mature petals via developmental remodeling. • There is no obvious one-to-one correspondence between spur length and pollinators in the four species of Aquilegia , and abiotic factors may be an important explanation for spur lengths in our study. The diversification of spur length in Aquilegia is often thought to be driven by pollinators. In this study, the morphology and pollination biology of four sympatric Aquilegia species distributed in China with different petal spur lengths were investigated through scanning electron microscopy, light microscopy, and field observations and measurements. The morphology and spur lengths of the four Aquilegia species differed: Aquilegia kansuensis has long incurved spurs (14.82 ± 0.18 mm), A. rockii has long straight spurs (16.34 ± 0.18 mm), A. semicalcarata has short slender spurs (5.16 ± 0.17 mm), and A. ecalcarata is effectively spurless (1.20 ± 0.03 mm). Early petal development was similar among the species; petals undergo initiation and delayed development, resulting in mature petals with different spur lengths and morphologies via developmental remodeling. The long spurs of A. kansuensis and A. rockii were derived from an increased cell number and anisotropic cell expansion, with well-developed secretory tissue forming at the spur bottom. No secretory tissue formed in the spurs of A. semicalcarata and A. ecalcarata , even though their cell number increased. Although their spur morphology and nectary structure show considerable differences, the pollination systems of the four species are similar. Rhingia campestris is the dominant pollinator of A. kansuensis, A. semicalcarata , and A. ecalcarata , whereas Pipiza familiaris is the dominant pollinator of A. rockii. Both R. campestris and P. familiaris forage for pollen when visiting flowers. Given that the four species studied differ in spur length but are all pollinated by short proboscid pollinators, there is no obvious one-to-one correspondence between spur length and pollinator mouthpart length in A. rockii, A. kansuensis, A. semicalcarata and A. ecalcarata , which is similar to the pattern in the European Aquilegia alpina , and abiotic factors may be an important explanation for spur lengths in our study. [ABSTRACT FROM AUTHOR]

Abstract: For almost 150 years, the two monotypic genera Trochodendron and Tetracentron (Trochodendraceae) have been considered to share an unusual and primitive feature in angiosperms – the lack of vessels in their wood. Therefore, they have been classified in a basal position in the angiosperms. Our observations by light microscopy, low-vacuum environmental scanning electron microscopy (ESEM) and high-vacuum scanning electron microscopy (SEM) both in fresh and FAA-fixed materials consistently showed the presence of tracheary elements differentiated into two types in both genera. In Trochodendron, the tracheary elements can be divided into perforate vessel elements and imperforate fiber-tracheids and tracheids. The vessel elements show end and lateral walls. The pits on the end walls are elongate- broadened and do not have membranes or only a few remnants of them forming the perforation plates. The fiber-tracheids show crossfield pit pairs and sharp ends, and the tracheids show bordered pits. In Tetracentron, the tracheary elements comprise vessel elements and fibers. The vessel elements are similar to those of Trochodendron, whereas the fibers have no crossfield pit pairs but, rather, elliptical pits and sharp ends. Thus, both Trochodendron and Tetracentron are vessel bearing rather than vesselless, although their vessel elements are primitive. [Copyright &y& Elsevier]

• Stamen initiation and early development in male and female flowers are similar. • Staminodes in female flowers develop abnormally late with the anthers degenerating to different degrees. • Staminode morphology varies from staminiform, spoon-shaped, navicular, tongue-shaped to petaloid structures. • Anther wall formation is the basic type, simultaneous cytokinesis results in tetrahedral tetrads. The stamen is an extremely important reproductive organ in angiosperms. Androecia are the places where pollen is produced and show diversity in number and form; some are even reduced to staminodes or nectary structures in Ranunculales, but the development, morphology and structure of staminodes are completely unknown in Menispermaceae. In this study, the androecium development of Cocculus orbiculatus (L.) DC. was observed in detail for the first time under scanning electron microscopy and light microscopy. The results show that 1) stamen initiation and early development in male and female flowers are similar, while the staminodes in female flowers develop abnormally at later developmental stages, with the anthers degenerating to different degrees and becoming more or less flat structures; 2) in female flowers, the morphology and structures of staminodes are diverse: staminiform staminodes with tiny indehiscent anthers where 2-celled pollen grains or tetrads could be found in locules, or spoon-shaped, navicular, tongue-shaped and petaloid flat structures with an apex covered with secretions on the ventral surface; 3) in male flowers, the meiosis of the microspore mother cells occurs with simultaneous cytokinesis, the tetrads are tetrahedral, and the 2-celled pollen grains are tricolpate. In addition, the anther wall formation is the basic type. Compared to those of other groups in Ranunculales, the staminodes in Menispermaceae share some common characteristics with those of Lardizabalaceae, such as their position, number, size, morphology and degradation degree. [ABSTRACT FROM AUTHOR]