The shoot apex of Podostemaceae: De novo structure or reduction of the conventional type?

The paper reviews and discusses various interpretations of the shoot apex of Podostemaceae with special reference to subfamily Podostemoideae. Main questions concern (1) the proposed absence of a shoot apical meristem (SAM) in apical “meristemless” shoot tips of Podostemoideae and, as the consequence, the endogenous inception of leaf-borne leaves and branches and (2) the predicted stem bifurcation below a “terminal” dithecous (double-sheathed) leaf positioned instead of a shoot apex, as it is reported for subfamily Podostemoideae. Does the “meristemless” shoot apex represent a true evolutionary novelty? Does the view of stem bifurcation represent a new ramification pattern with the consequence that the “classical root–shoot model” of angiosperms is not valid for Podostemaceae? Both interpretations do not conform to previous studies that are complemented here by new data on the SAM of Zeylanidium olivaceum and Thelethylax minutiflora (Podostemoideae). Although a SAM is difficult to observe in the vegetative shoots of many Podostemoideae, it becomes well visible when the shoot passes into the flowering stage approaching the conspicuous shoot apex of floriferous shoots. The arguments of the absence of a SAM in vegetative shoots are not convincing and the endogenous origin of “leaf-borne leaves” appears questionable. Consequently, the “meristemless” shoot apex cannot be considered as a structure having evolved de novo. In the less advanced subfamilies Tristichoideae and Weddellinoideae, the leaf primordia develop only from a few apical cells of the outer shoot layer. This allows the conclusion that the surface layer of the apex in these subfamilies corresponds to the horizontally spread single-layered apical meristem of subfamily Podostemoideae. Similarly, the view of shoot bifurcation does not conform to the diachsial–sympodial branching pattern occurring in the cymose inflorescences of many Podostemoideae. This fact contradicts the presence of a terminal leaf.     

The ramification of Apinagia riedelii: A key to the understanding of the plant architecture of Podostemaceae,subfamily Podostemoideae

The study of the ramification pattern of Apinagia riedelii results in a new concept of the architecture of this species, with general implications to members of subfamily Podostemoideae with dithecous leaves. The presence of a subtending leaf below the floriferous shoot proves axillary branching also for species with dithecous leaves. Previous opinions of an unusual ramification mode by subfoliar or non-axillary branching or stem bifurcation in combination with dithecous leaves hitherto pleaded for Podostemoideae is refuted. Moreover, the view of the so-called dithecous leaves with one sheath (theca) at the ventral and one at the dorsal side of the leaf, previously regarded as initially connected with branching, has to be changed. The dithecous leaf arises from the branch and not from the mother shoot axis – as previously believed – and represents the addorsed hypsophyll, i.e., the first leaf (prophyll) of the floriferous branch. This finding leads to the conclusion that the lower sheath of the dithecous leaf is the ventral (not dorsal) sheath pointing to the branch and surrounding its flower bud with a ligule or an ochrea and a hood upon the bud. In this way, the branch and its flower bud become seemingly sunk in the leaf base. At the fusion of leaf basis and shoot results this enigmatic common tissue. The wings of the dorsal (upper) sheath of the dithecous leaf point to the mother shoot axis of the branch. Successive floriferous branches along the main stem disclose the shoot axis of A. riedelii as a monopodium (not sympodium) that develops an anthocladial (foliated) inflorescence in the form of a botrys or a compound botrys, respectively. Since it is generally difficult to define cymose or racemose inflorescences if subtending leaves are absent – which occur in most other species of subfamily Podostemoideae with dithecous leaves – the nature of these inflorescences is discussed anew. The findings on A. riedelii have consequences on our comprehension of the shoot architecture of Podostemoideae.     

Developmental Morphology of Roots and root-borne shoots ofPodostemum subulatum as compared withZeylanidium olivaceum (Podostemaceae—Podostemoideae) Part VII of the series ‘Morphology of Podostemaceae’

The root structure ofPodostemum subulatum is investigated and compared with that ofZeylanidium olivaceum. Podostemum has thread- or ribbon-like roots. The root tip consists of an inner apical meristem and a single-layered root cap. From roots arise numerous shoots of endogeneous origin. Their vascular bundle isab initio connected with the root bundle.By the simple (reduced) apical zonation, the roots ofPodostemum subulatum appear more advanced than the crustose roots ofZeylanidium olivaceum, which bear an ordinary (though asymmetrical) root cap. With regard to the endogeneous root-borne shoots, however,Zeylanidium appears more advanced because of the shoot dimorphism. The floriferous shoots have a short axis that grows plagiotropously above the crust surface, whereas the axes of the vegetative shoots are extremely short and remain, together with the apical meristem, within the crust. Only the leaves protrude from the crust surface.     

Comparative studies in the morphology of Crenias weddelliana and Maferria indica with reference to Sphaerothylax abyssinica (Podostemaceae: Podostemoideae)

The scope of morphological plasticity of vegetative structures among Podostemoideae (Podostemaceae) is documented for Crenias weddelliana, a neotropical species, Maferria indica, a palaeotropical species, and Sphaerothylax abyssinica, from Kenya, and compared with related taxa. The study highlights intrinsic characters of the widely enigmatic plant body of many species of the subfamily Podostemoideae. These include dorsiventrality of shoots occurring irrespective of gravity, incurvate distichy and one‐sided spirodistichy correlated with shoot dorsiventrality, asymmetric leaves, and several types of positioning of the two prophylls and inflorescence structures. The homogeneity of hairs of the ‘Zeylanidium olivaceum type’ established on the subulate leaves of some Indian species is of taxonomic value. The latter also applies to the stipella (not stipule) on the asymmetric compound leaf in New World species. The morphological data represent a framework of features consistent for the subfamily. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 138 , 63–84.     

Phyllotaxis in two species ofRubia,R. akane andR. sikkimensis

Phyllotaxis and vascular course in the vegetative shoots ofRubia akane andR. sikkimensis were studied. Each node of both species has a whorl of four leafy members among which two are true leaves. Arrangement of the true leaves is not decussate but bijugate, i.e., opposite leaves are arranged spirally. Bijugy was ascertained not only by gross morphology but also by arrangement of primordia around the shoot apex and vascular course through several internodes. Divergence angle differed widely with internodes even within a single shoot and with shoots even in the internodes which are separated by a same number of nodes from the apex. Mean divergence angles obtained for five youngest internodes of some shoots were between 49.4° and 61.8° inR. akane and between 53.6° and 59.4° inR. sikkimensis. Young seedlings ofR. akane showed decussate phyllotaxis in the lowermost several internodes. In the internodes near the lower end of the bijugate part, the divergence angle was wider than in the upper internodes. The directions of the phyllotactic spirals in the main axis and the lateral branches were either homodromous or antidromous, and those in the oppositely paired branches also were either homo- or antidromous.     

Shoot apex and spathella: two problematical structures of Podostemaceae–Podostemoideae

The presence of a shoot apex and shoot apical meristem (SAM), said to be absent in subfamily Podostemoideae (Podostemaceae), is confirmed for Marathrum utile and M. foeniculaceum. The vegetative shoot axis is terminated by a small group of meristematic cells which are surrounded by the tissue of the adnate bases of foliage leaves. The slightly bulged tip of the shoot apex is embraced by the youngest leaf, facing the apex with its adaxial side. The study also refers to the spathella, a cup-shaped structure covering obligatorily the young flower bud in Podostemoideae. The occurrence of two separate peaks in the young spathella of M. foeniculaceum supports the view that the spathella is formed by two fused bracts (hypsophylls). The two bracts are perpendicular to the distichous foliage leaves below the spathella. The scaly leaflet on the spathella of A. latifolia apparently does not represent a rudimentary blade of the spathella, but is interpreted as a separate bract. The occasional occurrence of scales below or above the spathella points to a reduction of bracts that were originally present in greater number on the pedicels.     

Neglected features of probable taxonomic value in Podostemaceae: The case of Polypleurum

The paper reports on hitherto largely neglected discriminative characters in Polypleurum stylosum, P. elongatum, P. minus, as well as the problematic P. munnarense (Podostemaceae, subfam. Podostemoideae) from India and Sri Lanka. The characters discussed include dimorphism of floriferous and vegetative shoots, leaf dimorphism, presence of peculiar floating trichomes on vegetative leaves, and presence of silica bodies in root and shoot tissue. In addition, anatomical pecularities (well-developed cuticle covering the ovary and ovules, cell inclusions in the form of droplets, and presence of idioblasts with firm inclusions of unknown compounds) and specific morphological features (presence of an apical septum in the gynoecium) are documented. All these features point to different developmental and physiological properties of the species concerned, thus signaling separate evolutionary pathways. They may help to elucidate phylogenetic relationships at various taxonomic levels and may prove useful for the delimitation of the genus.     

Tolerance of peanut to excess boron

The tolerance ofArachis hypogaea cv. Shulamit to high concentrations of B in nutrient solution, [B]o, was determined under greenhouse conditions that promoted the production of vegetative dry matter. Plants grew in large containers in which a root zone of nutrient solution was separated from a pod zone of soil. Grain yield was reduced at a calculated [B]o-threshold of 0.29 mM, which was associated with a concentration of B in the vegetative shoots that was approximately four times larger than the control. Symptoms of B toxicity occurred on leaves as young as the third unfolded leaf from the shoot apex before the [B]o-threshold. Excess B caused a relatively larger decrease in pod number than in vegetative shoot weight, which was high in all treatments (78 g d.wt/plant) and it did not decrease single grain weight. It was suggested that the tolerance of grain development to excess B was a consequence of the high ratio of vegetative matter to pod number.     

How does spittlebug oviposition affect shoot growth and bud production in two willow species?

We measured the effects of oviposition by the spittlebug Aphrophora pectoralis on shoot growth and bud production in two willow species, Salix miyabeana and Salix sachalinensis. In autumn, adult females of A.pectoralis insert their ovipositor into the apical region of 1-year-old shoots, resulting in the death of most shoot tips within 1week. Consequently, an increase in the number of dead buds and a decrease in the number of vegetative buds on 1-year-old shoots was recorded. In the following spring, the growth of current-year shoots was greatly increased on 1-year-old shoots damaged by spittlebug oviposition. Furthermore, spittlebug oviposition increased the production rate of vegetative buds in both S.miyabeana and S.sachalinensis. However, no impact on the production rate of reproductive buds was detected in either willow. We conclude that the compensatory growth of current-year shoots and an increase in vegetative buds in the two willow species was caused by oviposition of A.pectoralis.     

In vitro organogenesis from shoot tip,internode, and leaf explants of Ulmus x ‘Pioneer’

Shoot tip explants of the hybrid cultivar Pioneer responded poorly to initial attempts to establish shoot proliferating cultures on Murashige and Skoog (MS) medium containing 2 or 4 µM benzyladenine (BA) with a four week subculture interval. A combination of weekly subcultures and an MS medium containing 2 µM BA produced shoot proliferating cultures sufficient for micropropagation. Shoot organogenesis was obtained when callus derived from internodes of actively elongating shoots was transferred from a primary medium containing various cytokinins to a secondary medium containing MS salts and 10 µM BA. These small shoots elongated when transferred to a medium containing 2.5 µM BA. Adventitious shoots also differentiated on leaf tissue of Pioneer elm. These shoots appeared to differentiate with little if any intervening callus from the margins of leaves of in vitro grown shoots where these leaves touched the medium (MS medium containing 2 µM BA). Tissue cultured shoots from all sources were rooted, acclimated, and transplanted to the greenhouse or field with good success.Salaries and research aupport provided by State and Federal Funds appropriated to the Ohio Agricultural Research and Development Center, The Ohio State University, and The Nursery Crops Research Laboratory. Journal Article No. 23-86.     

MORPHOLOGICAL STUDIES OF THE NYMPHAEACEAE (SENSU LATO). XIII. CONTRIBUTIONS TO THE VEGETATIVE AND FLORAL STRUCTURE OF CABOMBA

Six species of Cabomba have been examined although the anatomy of the vegetative axes is based on the study of only C. caroliniana and C. palaeformis. A plant consists of an erect short shoot with decussate leaves which bears axillary flowering shoots and rhizomes. A rhizome bears decussate leaves and may also form axillary flowering shoots or turn upward and become a new short shoot. The phyllotaxies of the flowering shoots are proximately decussate or ternate (C. piauhyensis). The flowering shoots with decussate phyllotaxy change to 1/3 phyllotaxy distally; they bear axillary flowers proximally, and extra-axillary flowers distally. Flowering shoots with ternate phyllotaxy do not change distally but each produces first axillary and then extra-axillary flowers. Decussate vegetative axes and flowering shoots have four vascular bundles; ternate vegetative axes and flowering shoots have six vascular bundles, distantly paired into two or three vascular bundle-pairs, respectively. An elliptical vascular plexus occurs at each node. Each leaf receives one bundle-pair from one trace and each flower three bundle-pairs. A two-level receptacular vascular plexus occurs in flowers; the proximal, larger portion provides traces to perianth and stamens and the distal, smaller portion becomes carpellary traces. Each of the three sepals typically receives five branch traces from a basal principal trace, and each of the three petals receives, typically, three branch traces from a basal principal trace. Sepals and petals generally occur in a single, basally connate whorl. Each stamen receives one trace. Each stamen of three-stamen flowers is opposite a petal; each stamen of six-stamen flowers is aligned with an interval between a petal and adjacent sepal. Each staminal trace, which is just above the principal petal trace, in a three-petal flower, is frequently adnate to the latter trace. Each carpel receives one principal trace from the distal, small extension of the receptacular plexus, and each principal trace becomes three conventional veins of a carpel. Ovules may be borne directly over one of the veins or in any position between veins and are supplied by branches of the nearest vein or nearest two veins. All traces, ovular supply veins and the proximal portions of all veins are amphicribral. The several anatomical and morphological differences in vegetative axes and flowers between Cabomba and Brasenia suggest a greater taxonomic distance between the two genera than commonly supposed. It is suggested that extra-axillary flowers in 1/3 helical and ternate flowering shoots of Cabomba might be advantageous in preventing anthesis of flowers beneath peltate leaves. The aberrant position might be the initial evolutionary step toward what, in other nymphaeaceous genera, has shifted each flower to an adjacent helix. It is proposed that the zigzag stem accompanying the trigonal and sympodial flowering shoots may offer greater stability and floatability in water than the monopodial form. Several suggestions are offered for the variability of ovular positions: 1) the variability is a vestige of former laminar placentation in conduplicate carpels; 2) it is a vestige of a primitive condition antedating the current close association of ovules with ventral carpellary veins; 3) it is an early stage of evolution which might have terminated in laminar placentation and cantharophily, but which was replaced by a trend toward myophily.     

Cell-lineage patterns in the shoot apical meristem of the germinating maize embryo

A fate map for the shoot apical meristem of Zea mays L. at the time of germination was constructed by examining somatic sectors (clones) induced by -rays. The shoot apical meristem produced stem, leaves, and reproductive structures above leaf 6 after germination and the analysis here concerns their formation. On 160 adult plants which had produced 17 or 18 leaves, 277 anthocyanin-deficient sectors were scored for size and position. Sectors found on the ear shoot or in the tassel most often extended into the vegetative part of the plant. Sectors ranged from one to six internodes in length and some sectors of more than one internode were observed at all positions on the plant. Single-internode sectors predominated in the basal internodes (7,8,9) while longer sectors were common in the middle and upper internodes. The apparent number of cells which gave rise to a particular internode was variable and sectors were not restricted to the lineage unit: a leaf, the internode below it, and the axillary bud and prophyll at the base of the internode. These observations established two major features of meristem activity: 1) at the time of germination the developmental fate of any cell or group of cells was not fixed, and 2) at the time of germination cells at the same location in a meristem could produce greatly different amounts of tissue in the adult plant. Consequently, the developmental fate of specific cells in the germinating meristem could only be assigned in a general way.Abbreviations ACN apparent cell number - LI, LII, LI-LII sectors restricted to the epidermis, the subepidermis, or encompassing epidermis and subepidermis - PCN progenitor cell     

Significance of the simultaneous growth of vegetative and reproductive organs in the prostrate annual Chamaesyce maculata (L.) Small (Euphorbiaceae)

To elucidate the significance of the simultaneous growth of vegetative and reproductive organs in the prostrate annual Chamaesyce maculata (L.) Small (Euphorbiaceae) from the standpoint of meristem allocation, we investigated plant architecture, meristem allocation, and the spatial and temporal patterns in vegetative growth and reproduction in the reproductive stage. The numbers of secondary and tertiary shoots successively increased by branching in the reproductive stage, and the sum of shoot length was greater in secondary shoots than in primary shoots. The specific shoot length (shoot length per shoot biomass) was greater in lateral shoots than in primary shoots, indicating efficient lateral shoot elongation. The internode length was shorter in secondary shoots than in primary shoots, increasing the number of nodes per shoot length in secondary shoots. Many nodes on a shoot generated two meristems, one of which committed to a flower and one to a lateral shoot. The number of reproductive meristems was greatest in tertiary shoots, and 96% of total reproductive meristems on shoots were generated in lateral shoots. On almost all nodes, the reproductive meristem developed into a flower, and 95–98% of the flowers produced a fruit. Therefore, vegetative growth by branching in the reproductive stage contributed to the increase in reproductive outputs. From the standpoint of meristem allocation, the simultaneous growth of vegetative and reproductive organs in prostrate plant species might be important for increasing the number of growth and reproductive meristems, resulting in the increase in reproductive outputs.     

Micropropagation and field evaluation of micropropagated plants of turmeric

A protocol was developed for in vitro propagation of turmeric cv `elite' using young vegetative buds from sprouting rhizomes. The shoot buds produced multiple shoots when cultured on MS solid medium supplemented with benzyladenine and 1-naphthalene acetic acid. The effect of various cytokinins on shoot multiplication was studied by culturing the shoot tips on MS liquid medium supplemented with benzyladenine, benzyladenine riboside, kinetin, kinetin riboside, zeatin, 6-,-dimethylallylaminopurine, adenine, adenine sulfate or metatopolin each at 10 M in combination with 1-naphthalene acetic acid (1 M). Significant differences were observed between the treatments. Liquid medium was more favourable than agar medium for shoot multiplication. Among the various concentrations of agar tested, 0.4% and 0.6% were the best and produced the highest number of shoots per explant. Among the different carbohydrates tested, sucrose, fructose, glucose, sugar cubes, maltose, levulose and market sugar were found to be equally effective for shoot multiplication and xylose, rhamnose, lactose and soluble starch were inhibitory. Ninety five percent of the micropropagated plants survived in sterilized soil in paper cups and all of them survived in the field. Among 48 plants, two plants showed variegated leaves on the tillers. The micropropagated plants showed a significant increase in shoot length, number of tillers, number and length of leaves, number of fingers and total fresh rhizome weight per plant when compared with conventionally propagated plants. RAPD analysis of 11 regenerated plants using sixteen 10-mer primers did not show any polymorphism.     

An in vitro microplant bioassay using clonal white ash to test for tall fescue allelopathy

Axillary shoots from three selected white ash (Fraxinus americana L.) clones were harvested from in vitro shoot cultures. Roots were initiated by pulsing excised shoots for eight days in the dark in MS medium supplemented with 2% sucrose, 0.7% agar, 5 M NAA, and 1 M IBA. Pulsed shoots were transferred to a root elongation medium consisting of 25% MS macrosalts, full-strength microsalts and organics, 1% sucrose, 0.7% agar and no auxins. When roots were visible (6–10 days after transfer to root elongation medium), microplants were transferred to vessels containing the same minimal medium and tall fescue (Festuca elatior var. arundinacea (Schreb.) Wimm.) leaf extracts, leaf leachates, or soil leachates from plant boxes with and without tall fescue sod. After four weeks in vitro, primary adventitious and secondary root growth was reduced by extracts obtained from 5 and 10 g ground leaves per 100 ml of medium. Leachates obtained from 5 g soaked leaves per 100 ml of medium stimulated primary root growth. Soil leachates from bare soil also stimulated primary root growth. Variation was observed among the clones for root growth when plantlets were grown in extracts or leachates from tall fescue.     

Cytokinins,donor plants and time in culture affect shoot regenerative capacity of American elm leaves

Cytokinins, donor plants and their time in vitro as well as basal media were investigated for their influence on shoot regenerative capacity of American elm (Ulmus americana L.) leaves. Leaves excised from six 2-year-old seedlings formed adventitious shoots when placed on Driver and Kuniyuki Walnut (DKW) medium supplemented with 7.5, 15 or 22.5 M of benzyladenine (BA) or thidiazuron (TDZ). Thidiazuron induced significantly higher regeneration percentages on elm leaves than BA, regardless of concentration used. Donor plant also affected the efficiency of shoot regeneration, with certain seedlings having 1.5 to 7 times more explants forming shoots as compared to other seedlings tested. By subculture 15, the average number of shoots per regenerating explant increased at least 3-fold for leaves on media with BA or TDZ for the one donor plant that survived continued subculturing. Leaf explants from donor plants with the highest regenerative capacity had a higher percentage of shoot formation on DKW than MS medium. Explants from productive donor plants should be placed on DKW medium supplemented with TDZ to improve shoot regeneration efficiency from American elm leaves.     

Periods of organogenesis in mono- and bicyclic annual shoots of Juglans regia L. (Juglandaceae)

The organogenetic cycle of shoots on main branches of 4-year-old Juglans regia trees was studied. Mono- and bicyclic floriferous and vegetative annual shoots were analysed. Five parent annual shoot types were sampled between October 1992 and August 1993. Organogenesis of summer growth units was monitored between 16 Jun. and 3 Aug. 1993. Variations over time in the number of nodes, cataphylls and embryonic green leaves of terminal buds were studied. The number of nodes of parent shoot buds was compared with the number of nodes of shoots derived from parent shoot buds. The spring growth units of mono- and bicyclic shoots consist exclusively of preformed leaves which were differentiated, respectively, during the spring flush of growth (mid-April until mid-May) or the summer flush of growth (mid-June until early August) in the previous growing season. Thus, winter buds may consist of flower and leaf primordia differentiated in two different periods during annual shoot extension. The summer growth units of bicyclic shoots consist of preformed leaves that were differentiated in spring buds during the spring flush of growth in the current growing season. Bud morphology is compared between spring and summer shoots.     

Phenotypic variation during micropropagation of the chimeralRhododendron ‘President Roosevelt’

The putative periclinal chimeraRhododendron xlimbatum President Roosevelt was used to study the origin of shoots in vitro. Genotypic segregation readily occurred in vitro. Numerous phenotypes were observed, although most shoots were either entirely green or maintained the original variegation pattern. Derivatives of the third apical layer were rarely involved in shoot formation. A reversed chimeral form was isolated. Adventitious shoots were usually miniaturized and rapidly proliferating, but axillary shoots had thicker stems, larger leaves and proliferated more slowly. Corolla tissue produced stunted, leafy shoots; no variegated shoots were produced from floret explants. In shoot tip cultures the addition of 40M 2iP without IBA resulted in the greatest number of shoots. Explant choice was the most critical factor for maintenance of foliar variegation.     

Eriophyoid mite damage in Vitis vinifera (grapevine) in Australia: Calepitrimerus vitis and Colomerus vitis (Acari: Eriophyidae) as the common cause of the widespread ‘Restricted Spring Growth’ syndrome

Leaf and shoot distortions and retarded shoot growth in Vitis vinifera L. prevalent in Australian vineyards in early spring, were investigated in replicated field experiments over 3 yrs. Leaf distortion and retarded shoot growth were identified as damage due to feeding of extremely high populations of over-wintered deutogynes of Calepitrimerus vitis (Nalepa) (grape rust mite). This damage was hitherto known in Australia as Restricted Spring Growth (RSG), a syndrome comprising several growth abnormality symptoms, none with a clearly identified cause or a successful treatment. A successful treatment against C. vitis was used to selectively eliminate RSG, while C. vitis numbers were recorded using a validated trapping technique; intercepting deutogynes migrating from winter shelters in the wooden vine structure, to emerging green tissues. Severe leaf distortion was associated with >400 C. vitis deutogynes per spur, while >1000 per spur had the added effect of severely retarding shoot growth. A 43.0–47.2% shoot length reduction was recorded for Cabernet Sauvignon, 27.1–32.8% for Sauvignon Blanc, when 4–6 leaves were separated. Symptoms were most prominent up to 8–9 separated leaves, however 24.7–30.4% shoot length reduction was still evident at flowering, and 12.8% circa fruit set. C. vitis effect on vine fruitfulness, and yield parameters at fruit set, were also studied. Once successfully treated to prevent C. vitis damage, poor bud burst remained evident in some vineyards. Surveys of unburst buds from such vineyards revealed presence of Colomerus vitis (Pagenstecher) (grape bud mite). When Col. vitis numbers in unburst buds reached 100–500 per bud, apical meristems of primary, and commonly also secondary buds were dead, preventing bud burst. The remaining living scale tissue was distinctly scarred. Bud and associated shoot damage were documented. Retarded shoot growth and leaf distortion, previously attributed to RSG, are misdiagnosed C. vitis spring feeding damage. Clustered high infestations of Col. vitis can cause bud-axis necrosis, bud burst failure, shoots with short basal internodes, and short, thin, zigzagged shoots with absent fruit clusters; all previously considered RSG.This revised version was published online in May 2005 with a corrected cover date.     

Endophytic and epiphytic phyllosphere fungi of red-osier dogwood (<Emphasis Type="Italic">Cornus stolonifera</Emphasis>) in British Columbia

Endophytic and epiphytic phyllosphere fungi associated with red-osier dogwood (Cornus stolonifera), a deciduous shrub, were examined in coastal British Columbia, Canada. Current-year shoots were divided into four types based on the absence or presence of inflorescence and secondary elongated shoots at the apex of primary shoots. Leaves on these shoots were then classified into six categories so as to examine the effect of flowering, secondary shoot elongation, and shoot order within current-year shoots on the occurrence of phyllosphere fungi. Species composition of fungi was markedly different between the interior and surface of leaves, whereas it was relatively similar among the six leaf categories in the interior or on the surface. Frequencies of the eight major species were not different between leaves on flowering and nonflowering shoots. The frequency of Colletotrichum gloeosporioides in the leaf interior was greater on leaves on the primary shoots that elongated the secondary shoots than on those that did not, and was greater on leaves on the primary shoots than on those on the secondary shoots. On the other hand, secondary shoot elongation and shoot order had no effect on the frequencies of C. gloeosporioides and the other seven epiphytes on leaf surfaces.