The effect of SEM preparation on pit membrane remnants in vessel element end-walls of primitive angiosperms

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.     

Growth reactions of Pinus sylvestris L. and Quercus pubescens Willd. to drought years at a xeric site in Valais, Switzerland

In Valais, an inner-Alpine dry valley in Switzerland, low-elevation Scots pine (Pinus sylvestris L.) forests are changing. While pine shows high mortality rates, deciduous species, in particular pubescent oak (Quercus pubescens Willd.), are becoming more abundant. We hypothesise that increasing drought and the species-specific drought tolerance are key factors in these processes. In this study, the growth reaction to drought years of pine and oak growing at a xeric site in Valais was analysed using dendrochronological and wood anatomical methods. Congruent with theoretical expectations, the tree-ring widths of both species, the mean lumen area of earlywood vessels in oak and the number of tracheids in a radial row in pine decreased in response to dry conditions. However, both species also showed reactions deviating from those known from mesic sites: In oak, the mean lumen area of latewood vessels increased in drought years. In pine, in the driest year of the period (1976), the mean radial diameter increased in latewood and decreased only slightly in earlywood. These results emphasises that the process of wood formation and cell functionality at xeric sites is not completely understood yet. Both species seem to have difficulties to adapt the size of their water-conducting cells to strongly reduced water availability in drought years. Additionally, the cell number is strongly reduced. Thus it remains unclear if both species can maintain sufficient water transport under increasingly dry conditions.     

Wood and stem anatomy of Lardizabalaceae, with comments on the vining habit, ecology and systematics

CARLQUIST, S., 1984. Wood and stem anatomy of Lardizabalaceae, with comments on the vining habit, ecology and systematics. Qualitative and quantitative data, based mostly upon liquid-preserved specimens, are presented for Akebia, Roquila, Decaisnea, Holbodia, Lardizabala, Sinofranchetia and Stauntonia . Because Decaisnea is a shrub whereas the other genera are vines, anatomical differences attributable to the scandent habit can be considered. These include exceptionally wide vessels, a high proportion of vessels to tracheids (or other imperforate trdcheary elements) as seen in transection, simple perforation plates, multiseriate rays which are wide and tall, and pith which is partly or wholly sclerenchymatous. With respect to ecology, two features are discussed: spirals in narrower vessels may relate to adaptation to freezing in the species of colder areas, and crystalliferous sclereids seem adapted in morphology and position to deterrence of phytophagous insects or herbivores. The wood may provide mechanisms for maintaining conduction even if wider vessels are deactivated temporarily by formation of air embolisms. Wood and stem anatomy of Lardizabalaceae compare closely to those of Berberidaceae and of Clematis (Ranunculaceae), as well as to other families of Berberidales. Decaisnea is more primitive than these in having consistently sralariform perforation plates and in having scalariform pitting on lateral walls of vessels. A tentative listing of anatomical features which may correspond to generic limits is given.     

Comparative studies of vegetative anatomy in the Theaeeae of Sri Lanka

Anatomical characters of the mature leaf blade, petiole, young stem and wood were examined in order to substantiate taxonomic boundaries between genera and species of Theaeeae in Sri Lanka. Two species of Temstroemia , one of Adinandra , four of Eurya and two of Gordonia were studied.
The presence of sclereids in most organs of the plant was found to be a common character within the family. However, three distinct types of sclereid are reported. Two basic types of stomata, anomocytic and gordoniaceous, are recognized. The origin of phellogen in the young stems is pericyclic in Gordonia and subepidermal in the other three genera. The species within these genera also appear to have several distinctive characters of their own. Important wood characters have been tabulated in order to illustrate the primitive and advanced characters. Gordonia , especially, exhibits anatomical features which are quite different from those of Temstroemia, Adinandra send Eurya.