Rachis vascularization and leaflet venation in developing leaves of Fraxinus pennsylvanica

1985 ◽  
Vol 63 (12) ◽  
pp. 2383-2392 ◽  
Author(s):  
Philip R. Larson
Keyword(s):  
Leaf Development ◽  
Close Association ◽  
Terminal Leaflet ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Leaf Base ◽  
Lateral Leaflet ◽  
Curve Upward

Leaves of Fraxinus pennsylvanica are served by a double trace that exits the stem vasculature through a single gap. During embryonic leaf development, the leaf traces subdivide in the node to produce subsidiary bundles that differentiate acropetally in the leaf base and basipetally in the stem. The acropetal bundles converge distally in the node to form a rachis vasculature consisting of a semicircular arc joined by a ventral chord. Each lateral leaflet is vascularized by bundles contributed by both the semicircular arc and the ventral chord of the rachis. One rachis ridge bundle divides to form two leaflet ridge bundles and a new rachis ridge bundle diverges from the ventral chord. The leaflet ridge bundles diverge as basal veins and subsequent secondary veins diverge from the midvein in an approximate right–left sequence. Green ash has odd pinnate leaves; the terminal leaflet is vascularized by the rachis residual following departure of the last leaflet pair. Secondary veins extend to the lamina margins and then curve upward to initiate the marginal loops of the brochidodromous venation. Periclinal divisions occur in close association with secondary veins in the prospective plate meristem region. Anticlinal divisions occur in subepidermal layers of the internal ridge points in the prospective palisade mesophyll region.The latter divisions probably contribute both to lamina extension and to spreading of the conduplicately folded lamina wings.

Heteroblastic seedlings of green ash. I. Predictability of leaf form and primordial length

1986 ◽  
Vol 64 (11) ◽  
pp. 2645-2649 ◽  
Author(s):  
E. K. Merrill
Keyword(s):  
Leaf Development ◽  
Leaf Growth ◽  
Leaf Primordia ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Leaf Form ◽  
Compound Leaf ◽  
Controlled Conditions ◽  
Plastochron Index

Green ash (Fraxinus pennsylvanica var. subintegerrima) seedlings are heteroblastic; during development they produce two types of leaves, simple and compound. When grown under controlled conditions, the sequence of leaf types is predictable. Simple leaves are always at the first four nodes; compound leaves are always at node 8 and above. Nodes 5 through 7 have progressively fewer simple leaves and more compound leaves. Leaf growth on seedlings meets the preconditions of the plastochron index and leaf plastochron index. These indices, as well as the length of single expanding leaves, can be used to predict lengths of leaf primordia at nodes 4 and 8 so that early, simple and compound leaf development can be compared in further studies of green ash.

Heteroblastic seedlings of green ash. II. Early development of simple and compound leaves

1986 ◽  
Vol 64 (11) ◽  
pp. 2650-2661 ◽  
Author(s):  
E. K. Merrill
Keyword(s):  
Early Development ◽  
Leaf Primordia ◽  
The Other ◽  
Terminal Leaflet ◽  
Green Ash ◽  
Lateral Leaflet ◽  
Leaf Type ◽  
Simple Leaf ◽  
Compound Leaf

Simple and compound leaf primordia of green ash seedlings differ in shape from initiation. Simple leaf primordia are flattened until their lamina margins grow out at a primordial length of 150 μm. Compound leaf primordia are rounded and peglike at initiation and lateral leaflet buttresses appear when primordia are 150 μm long. Terminal leaflet margins appear when compound leaf primordia are 200 μm long. At initiation both types of leaf primordia are composed of densely cytoplasmic cells. Vacuolation proceeds so that densely cytoplasmic cells remain only in areas developing blades and leaflets and in procambium. Because simple and compound leaves of green ash differ from initiation, neither leaf type can be considered to result from a change in the ontogeny of the other.

scholarly journals Desiccation Tolerance of Green Ash and Sugar Maple Fine Roots

2009 ◽  
Vol 27 (4) ◽  
pp. 229-233 ◽  
Author(s):  
Gary W. Watson
Keyword(s):  
Root Growth ◽  
Fine Roots ◽  
Acer Saccharum ◽  
Sugar Maple ◽  
Fine Root ◽  
Cell Damage ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Root Electrolyte Leakage ◽  
Bare Root

Abstract Exposed fine roots are subject to desiccation, which may affect their survival as well as new root growth following bare root transplanting. Fine roots of dormant 1-year-old green ash (Fraxinus pennsylvanica) and sugar maple (Acer saccharum) seedlings, subjected to desiccation treatments of 0, 1, 2, or 3 hours in December and March, lost up to 82 percent of their water. Root electrolyte leakage, a measure of cell damage, tripled after three hours of desiccation. The increase was moderately, but significantly, greater in March for both species. Desiccation treatments had no effect on fine root survival. Growth of new roots (RGP) was also unaffected by desiccation treatments. RGP of maple was greater in March than December, but not ash.

Tolerance of Planed Hardwoods to Spring Flooding

1977 ◽  
Vol 1 (3) ◽  
pp. 23-25 ◽  
Author(s):  
James B. Baker
Keyword(s):  
Populus Deltoides ◽  
Growing Season ◽  
Liquidambar Styraciflua ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Nyssa Aquatica ◽  
Eastern Cottonwood ◽  
Platanus Occidentalis ◽  
Water Tupelo ◽  
Root Collar

Abstract Cuttings of eastern cottonwood (Populus deltoides) and seedlings of sweetgum (Liquidambar styraciflua), water tupelo (Nyssa aquatica), American sycamore (Platanus occidentalis), and green ash (Fraxinus pennsylvanica) were planted on a slackwater clay (Vertic Haplaquept) in western Mississippi in two consecutive years and inundated soon after foliation. During each of the two years, survival following flooding was consistently high for water tupelo, green ash, and sycamore, low for cottonwood, and intermediate for sweetgum. With the exception of green ash, however, all species lost their leaves and died back to the root collar during flooding. Thus trees, other than ash, that were living at the end of the growing season had originated from root collar sprouts.

Sex Differences in Green Ash

1979 ◽  
Vol 3 (4) ◽  
pp. 173-174
Author(s):  
John T. Talbert ◽  
Robert D. Heeren
Keyword(s):  
Sex Differences ◽  
First Generation ◽  
Tree Improvement ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Improvement Program ◽  
Male And Female ◽  
Sufficient Variation ◽  
Natural Stands ◽  
Male Superiority

Abstract A disproportionately large number of first-generation selections from natural stands of green ash (Fraxinus pennsylvanica Marsh.) have been male. A study was undertaken to determine if male and female green ash differed in several important economic characteristics. Only straightness differences could be shown to be statistically significant, and, even for this trait, several opinions were needed to detect male superiority. Sufficient variation should exist in natural stands to allow inclusion of superior individuals of both sexes in a tree-improvement program.

Shoot ontogeny in Fraxinus pennsylvanica (green ash). II. Development of the inflorescence

1989 ◽  
Vol 67 (7) ◽  
pp. 1966-1978 ◽  
Author(s):  
W. R. Remphrey
Keyword(s):  
Fruit Set ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Dioecious Species ◽  
Male And Female ◽  
Floral Buds ◽  
Growing Seasons ◽  
Female Inflorescence ◽  
Mature Flower ◽  
Floral Apex

From initiation to fruit set, which occurs over three growing seasons, eight stages are recognized in the development of axillary inflorescences in the dioecious species Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern, (green ash). In the first season, buds are initiated in the axils of foliage leaves. As the shoots expand in the following spring, the buds complete their development. Although similar at first, differences begin to emerge between vegetative and inflorescence buds in that the latter produce robust second-order meristems, the incipient paracladia, protruding close to the original apex. After about 3–4 weeks, when the initiation of such buds is complete, the terminal and subtending lateral meristems present on each axis develop into a three-membered cluster of floral buds. There was a mean of 214.3 ± 12.2 floral buds initiated per female inflorescence, and the number generally increased with the length of the associated shoot. A ridge, the incipient perianth, begins to form around the periphery of each rounded floral apex. Male and female floral buds are not distinguishable at this stage, but the inflorescence buds are distinctly different from vegetative buds. The male and female buds then diverge in their development in that an identation forms at the summit of the incipient gynoecium and male buds initiate two or three anthers. By autumn, the gynoecium is distinctly conical, with an orifice at its summit, and the anthers are lobed. There is lobing of the perianth ridge, but in the mature flower distinct organs traceable to such lobes could not readily be identified.

An analysis of architectural parameters of male and female Fraxinus pennsylvanica in relation to crown shape and crown location

1990 ◽  
Vol 68 (9) ◽  
pp. 2035-2043 ◽  
Author(s):  
Campbell G. Davidson ◽  
William R. Remphrey
Keyword(s):  
Principal Component ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Male And Female ◽  
Lateral Shoots ◽  
Crown Shape ◽  
Sampling Height ◽  
Shape Class ◽  
Key Variables ◽  
Oval Shape

Architectural variables from male and female green ash (Fraxinus pennsylvanica var. subintergerrima (Vahl) Fern.) comprising three different crown-shape classes were analyzed at four different crown levels to determine which variables influenced crown shape. The narrow conical shape class had the largest mid shoot diameters and the smallest shoot tip abortion frequencies. The broad to round shape class had greater abortion frequency overall. In addition, there was less difference in shoot length between the top and bottom of the crown. The more oval shape class was intermediate for both shoot diameters and abortion frequency. Parent and daughter shoot lengths were longer, midshoot diameters larger, and elevation angles greater with increasing sampling height in the tree. Male trees had shorter shoot lengths and shorter and fewer daughter lateral shoots than female trees. Principal component analysis was used to identify shoot lengths, elevation angles, and abortion frequencies as potentially key variables in understanding crown shape in green ash. Interrelationships of many of the architectural variables suggest that a significant change in one may lead to changes in others, which ultimately would lead to changes in overall crown shape.

scholarly journals Variation in Aggressiveness of Ash Yellows Phytoplasmas

Plant Disease ◽  
2000 ◽  
Vol 84 (3) ◽  
pp. 282-288 ◽  
Author(s):  
W. A. Sinclair ◽  
H. M. Griffiths
Keyword(s):  
Fragment Length Polymorphism ◽  
Initial Strain ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Long Distance ◽  
Rapid Multiplication ◽  
Pcr Rflp ◽  
Polymerase Chain ◽  
Different Strains ◽  
Long Distance Movement

Twelve strains of phytoplasmas belonging to the ash yellows (AshY) group, from across the known range of AshY and representing six host species, were assessed for differences in ability to suppress growth and cause chlorosis in graft-inoculated Fraxinus pennsylvanica (green ash) and Catharanthus roseus (periwinkle). In each of two experiments with ash and one with periwinkle, different strains caused significantly different degrees of growth suppression and loss of foliar greenness. These growth and color impacts were positively and significantly correlated among experiments and between ash and periwinkle, indicating strain variation in aggressiveness. After two strains that differed in aggressiveness were coinoculated to periwinkle plants, polymerase chain reaction/restriction fragment length polymorphism (PCR/RFLP) assays of DNA from leaves remote from the inoculation sites revealed the presence of the aggressive strain sooner and more frequently than that of the less aggressive strain. Thus, aggressiveness was associated with more rapid multiplication and/or movement than was achieved by the less aggressive strain. When either strain was inoculated 11 weeks before the other into the same plant, only the initial strain could be detected after a further 12 weeks of incubation. Thus, the initial strain or its effect on the host may have interfered with multiplication and/or long-distance movement of the second strain. A concept of preemptive dominance is proposed to account for detection by primary PCR of only single phytoplasma strains in plants that may harbor two or more strains.

Biology of Caloptilia fraxinella (Lepidoptera: Gracillariidae) on ornamental green ash, Fraxinus pennsylvanica (Oleaceae)

2009 ◽  
Vol 141 (1) ◽  
pp. 31-39 ◽  
Author(s):  
M.L. Evenden
Keyword(s):  
Management Program ◽  
Biological Information ◽  
Fraxinus Pennsylvanica ◽  
Immature Stages ◽  
Green Ash ◽  
Emergence Period ◽  
Leaf Mining ◽  
Ash Trees ◽  
A Site ◽  
Caloptilia Fraxinella

AbstractThe ash leaf cone roller, Caloptilia fraxinella (Ely), is a leaf-mining moth that has recently become a significant pest of horticultural ash, Fraxinus L., species in communities throughout the western prairie provinces of Canada. The study examines the spatial and temporal within-host distribution of immature stages of C. fraxinella on green ash, Fraxinus pennsylvanica Marsh. Female C. fraxinella showed a preference for oviposition sites in the lower canopy and on the south side of the tree at the beginning and middle of the 3-week oviposition period, respectively, but no preference at the end of the period. Oviposition was constrained temporally and occurred mainly just after green ash bud flush. Immature stages were sampled throughout the growing season, and measured widths of larval head capsules showed five instars. Fourth-instar larvae disperse from the mined leaflet to a new leaflet, roll it into a cone, and pupate. Neither canopy height nor ordinal direction affected the position of larvae in the canopy, but numbers of immature stages varied by tree within a site. Female and male moths eclose from rolled leaf cones synchronously throughout the emergence period. The study provides some of the basic biological information required to design an integrated pest management program to target this emerging pest of horticultural ash trees.

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