Fine-structural observations on necrotic adventitious root apices inGlechoma hederacea L.

Summary In certain adventitious roots ofGlechoma hederacea necrosis may already occur in the primordium before emergence from the parent shoot. In such roots the apical organization is lost and the root becomes dormant soon after emergence and covered by a brown mantle derived from the root cap and apical initials. The tangential walls of cells comprising the mantle are frequently conspiciously thickened and contain numerous flecks. The arrangement of the flecks resembles somewhat the suberin lamellae in other species but staining reactions failed to indicate the presence of suberin in the dormant root ofG. hederacea.     

Tentoxin effects on infrastructure and greening of ivyleaf morningglory (Ipomoea hederacea var. hederacea) cotyledons

The effects of 20 μM tentoxin on mesophyll chloroplast ultra-structural development, chlorophyll organization and accumulation, and pigment transformations in cotyledons of dark-grown, 4-day-old ivyleaf morningglory [Ipomoea hederacea (L.) Jacq. var. hederacea]were monitored. After 6 h of white light (200 μEm^?2T.s^?1), many plastids of tentoxin-treated tissues contained prolamellar bodies or inconsistent internal membrane orientation in contrast to the uniform internal membrane orientation and absence of prolamellar bodies in controls. Grana stacking did not progress beyond three to four disc loculi in tentoxin-treatments, and fret membranes were usually discontinuous and reduced. Cylindrical or cupped grana appeared in many chloroplasts after 3 days of light, while other chloroplasts in which disruption was more pronounced had few grana except for remnants, but usually did possess vesicles or structures resembling prolamellar bodies. Tentoxin had no apparent effect on stroma density or plastoglobuli size and number. No starch grains appeared in any of the tentoxin treatments, whereas they appeared after 24 h in controls. Initial protochlorophyllide content and its photoconversion to chlorophyllide and subsequent Shibata shift were not affected by tentoxin. Chlorophyll accumulation rates in tentoxin-treated cotyledons were about 10% of control rates during the first 24 h of greening and about 20% of controls from 48 to 72 h of greening. Chlorophyll alb ratio and PSU size (total Chl/P700) were not significantly affected by tentoxin.     

Production ecology ofBolboschoenus maritimus (L.)Palla (Scirpus maritimus L. s.l.)

Measurements were made, for several seasons, both of the growth rate and biomass production of stands ofBolboschoenus maritimus, the seasonal development of the vertical stand structure together with parallel measurements of microclimatological data including incoming global radiation. Water and bottom soil chemical analyses in relation to the nutrient content in the biomass were compared. The ecological adaptation of the acidophilic subspeciesB. m. ssp.maritimus, growing in south-Bohemian oligotrophic fishpond waters with that of the halophilic ssp.compactus was studied in experimental hydroponic cultures and the results discussed with the findings of other authors from different European habitats. The efficiency of solar energy conversion of incoming radiation was calculated by means of energy content biomass analysis.     

Inequality in the Development of the Axillary Members in Glechoma hederacea L.

The vegetative plant of Glechoma hederacea has leaves and axillarybuds arranged in opposite and decussate pairs. The two individualsof any pair of axillary members (i.e. buds or runners) are oftenunequal in size although the leaves subtending the particularpair of axillary members seldom show any obvious inequality.A quantitative investigation of this inequality of the axillarymembers was made on clonal material. The lengths of the pairsof axillaries at 191 nodes on 25 horizontally growing runners(stems) were recorded. The degree of inequality of one memberof each pair of axillaries on a number of these runners wascalculated as its percentage difference from the mean lengthof the particular pair of axillary members. The positions ofthe axillaries on the runners were relatable to the four orthostichiespresent on the axillary buds from which the runners developed.At the even nodes (i.e. the second, fourth, &c. formed nodes)there was always a considerable degree of inequality betweenthe members of any particular pair of axillaries. The longermembers invariably occurred on the orthostichy of the runnerwhich in the undeveloped axillary bud lay adjacent to its subtendingleaf. At the odd nodes the inequality between the members ofany pair of axillaries was usually not so great and occasionallythe members were equal. Although the longer axillaries werenot confined to any particular orthostichy there was often atendency for more to occur on one of the two possible orthostichieson any given runner. Fifteen terminal runner buds were grown vertically in narrow-boreglass tubes for a varying number of plastochrons. At the 67nodes at which it was certain that the pairs of axillary memberswere initiated after the beginning of the experiment a similarpattern of inequality was found to that occurring in the horizontalrunners. It is thus concluded that gravity plays no part indetermining such inequality. A comparison was made between the degree of inequality of oneof the individuals of each axillary pair at a total of 18 nodeson four horizontal runners and the inequality (calculated fromlaminal areas) of the leaves subtending these axillaries. Thedegree of inequality of the subtending leaves was usually muchless than that of their respective axillaries and bore no constantrelationship to the latter.     

Beobachtungen anBotrychium Lunaria (L.) Sw. undGenista sagittalis L.

Ohne Zusammenfassung     

Synchronization of protoplasts from Glycine max (L.) Merr. and Brassica napus (L.)

Cells of Glycine max originating in a suspension culture and cells of Brassica napus prepared from hypocotyls were synchronized. Synchronization was achieved by preparing protoplasts in the usual way and subsequently letting the protoplasts regenerate into cells by removing the cell-wall-digesting enzymes. More than 70% of the cells had divided synchronously at the end of the first cycle as determined by the mitotic index. The high frequency of mitosis critically depended on the osmolality of the medium. The duration of the S-phase was estimated by measuring the activity of thymidylate kinase as well as incorporation of [³H]deoxythymidine into acid-insoluble material. The data indicate that synchronization is induced by resetting the cell cycle.Abbreviations dTMP deoxythymidine 5-monophosphate - TCA trichloroacetic acid     

Plate 488. Wahlenbergia hederacea Campanulaceae

The ecology, distribution and taxonomic history of Ivy‐Leaved Bellflower, Wahlenbergia hederacea (L.) Rchb. are discussed, and the species is illustrated.     

Chromatin differentiation between Vigna radiata (L.) R. Wilczek and V. unguiculata (L.) Walp. (Fabaceae)

A comparative chromosomal evaluation was carried out between Vigna unguiculata (cowpea) and V. radiata (mung bean) with chromomycin A₃ (CMA₃)/4’,6-diamidino-2-phenylindole (DAPI) banding and fluorescent in situ hybridization (FISH) using 5S/45S ribosomal DNA (rDNA) probes. Both species had symmetric karyotypes (2n = 22), with prevalence of centromeres in chromosomes at median (m) and submedian (sm) regions and chromosomes ranging in size from 2.1 to 1.25 μm (V. unguiculata) and 2.18 to 0.93 μm (V. radiata). Three different banding patterns were identified for V. unguiculata: CMA₃⁺/DAPI⁰, CMA₃⁺⁺/DAPI^–, and CMA₃⁺/DAPI^–. The CMA₃⁺/DAPI⁰ bands were observed in the pericentromeric regions of all chromosomes, while the CMA₃⁺⁺/DAPI^– and CMA₃⁺/DAPI^– bands were co-localized with the 45S rDNA in the subtelomeric position (chromosomes B, G, and D, J, respectively) and in the proximal position in chromosome F. Two pairs of chromosomes (D and I) bearing interstitial 5S rDNA have been also identified. Vigna radiata displayed CMA₃⁰/DAPI⁺ bands distributed in the centromeric region of chromosomes B, C, and F, while CMA₃⁺⁺/DAPI^– bands were co-localized with the 45S rDNA sites in the subtelomeric position of the short arm in the F and K chromosome pairs. Three pairs of 5S rDNA sites were identified, the first in the proximal region of the long arm in chromosome E and the two others in the proximal and subterminal positions in the long arm of chromosome J. These data highlight some divergences regarding the amount and composition of the heterochromatin in both species, allowing the identification of individual chromosomes in V. unguiculata and V. radiata, and a comparison with other members of the Phaseoloid clade.     

Field studies on the ecology ofBolboschoenus maritimus (L.)Palla (Scirpus maritimus L. s. l.)

In an ecological field study, plants ofBolboschoenus maritimus (L.)Palla (Scirpus maritimus L. s. l.) growing in oligohaline and in mesohaline soils were compared. Differences between both populations mainly concerning osmotic potential, water potential and ionic concentrations could be related with the salt content at both sites, whereas transpiration and photosynthesis did not differ significantly. Water potential of the cell sap was affected by several external factors.