Shoot ontogeny in Fraxinus pennsylvanica (green ash). I. Seasonal cycle of terminal meristem activity

1989 ◽  
Vol 67 (6) ◽  
pp. 1624-1632 ◽  
Author(s):  
W. R. Remphrey
Keyword(s):  
Seasonal Cycle ◽  
Histological Analysis ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Heat Unit ◽  
Foliage Leaf ◽  
Axillary Meristems ◽  
Bud Initiation

Terminal meristem ontogeny of mature Fraxinus pennsylvanica var. subintegerrima (Vahl) Fern, (green ash) was investigated by bud dissection, histological analysis, and scanning electron microscopy. The shoots were completely preformed and bud-scale initiation for the next bud began in the spring shortly before any visible sign of swell. Foliage-leaf initiation began in May and ceased in late June or early July, but there were certain differences in primordium production patterns between the two trees investigated and between the years of the study. Although temperature, as measured by heat-unit accumulation, played a significant role in the onset of shoot expansion and primordium initiation, its importance in controlling these processes diminished as the season progressed. Buds formed in the axil of every leaf primordium, but those in the axils of scales remained small. There was evidence of axillary bud initiation as early as the P1, stage. By P2 or P3 there was a clearly discernable shell zone of elongated cells. Such cells had relatively large vacuoles concentrated at each end, in contrast with the essentially nonvacuolate cells of the incipient bud meristem. In the terminal resting bud, there were well-developed scale-axil buds and protruding axillary meristems associated with foliage-leaf primordia.

Structure and development of terminal bud scales in green ash

1990 ◽  
Vol 68 (1) ◽  
pp. 12-20 ◽  
Author(s):  
E. K. Merrill
Keyword(s):  
Developmental Stages ◽  
Early Summer ◽  
Leaf Primordia ◽  
Apical Region ◽  
Fraxinus Pennsylvanica ◽  
Green Ash ◽  
Foliage Leaf ◽  
Terminal Bud ◽  
Terminal Buds ◽  
Early Developmental

Structure and development of terminal bud scales of green ash (Fraxinus pennsylvanica var. subintegerrima) were studied to provide a basis for comparison with foliage leaves of the same species. To identify early developmental stages of bud scales, structure and phenology of terminal buds were investigated first. Overwintering terminal buds have typically three or four pairs of bud scales and three to six pairs of foliage leaf primordia. Bud scales have a flattened base topped by rudimentary leaflets. After bud break, the first leaf primordia that are initiated develop and mature into terminal bud scales by early summer. Although morphology and anatomy of mature foliage leaves and bud scales are very different, primordia of leaf forms are similar until they reach a length of 500 μm. At that length both leaf forms have a base and apical leaflets. Bud scale bases widen and elongate without much thickening, while growth in the apical region is restricted. Marginal growth of the bud scale base is different from that described for most leaf blades. Terminal bud scales could be interpreted as being ontogenetically derived from foliage leaf primordia.

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.

The rotated-lamina syndrome. I. Ulmaceae

1993 ◽  
Vol 71 (2) ◽  
pp. 211-221 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Leaf Blade ◽  
Early Stage ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Foliage Leaf ◽  
Normal Orientation ◽  
Ulmus Glabra ◽  
Young Leaves ◽  
Final Orientation ◽  
Zelkova Serrata

In a number of plants, mostly woody, the components of the buds are arranged so that the laminae of the young leaves all face towards the same (upper) side of the bud, rather than towards the bud apex; in axillary buds they usually face towards the parent axis. This situation has been known for many years. For convenience, the general case is here called the rotated-lamina syndrome. There have been very few developmental investigations of how the laminae attain their unusual orientation, and these have come to different conclusions about cases in the Ulmaceae. This paper reports a detailed investigation of the syndrome in Ulmus glabra and Zelkova serrata, with comparative observations on other Ulmaceae, including cases in Celtis that do not exhibit the syndrome. The syndrome arises by different means in Ulmus and Zelkova. In Ulmus the leaf primordium is asymmetrical from the outset, the leaf blade region is obliquely dorsiventral from an early stage, and further asymmetrical growth of the leaf buttress rotates the whole leaf blade region into its final orientation as it develops. Individual shoots show heteroblastic development in progressing from bud scale to foliage leaf initiation, in increasing accentuation of the rotated-lamina syndrome, and in an increasing degree of dorsiventrality. In Zelkova, as previously described, the leaf blade region appears first as a radially symmetrical upgrowth, and it acquires dorsiventral symmetry directly in the rotated position. In Celtis spp. the lamina arises in a quite normal orientation, but reorients as it emerges from the bud. The leaf primordia of all species studied show asymmetry in other aspects, particularly in respect of stipule development, and these seem to be general features of the organisation of dorsiventral shoots. Key words: Ulmus, Zelkova, Celtis, leaf, development, dorsiventrality, lamina rotation.

INTERPRETATION OF THE MORPHOLOGY OF VARIOUS NATURALLY OCCURRING ABNORMALITIES OF THE INFLORESCENCE OF WHEAT (TRITICUM)

1967 ◽  
Vol 45 (11) ◽  
pp. 2073-2080 ◽  
Author(s):  
B. C. Sharman
Keyword(s):  
Shoot Apex ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Normal Pattern ◽  
Naturally Occurring ◽  
Foliage Leaf ◽  
Lateral Spikelet ◽  
Relative Rarity ◽  
The Stability

At the onset of inflorescence production, the shoot apex continues to initiate leaf primordia, in the same alternating sequence of the foliage primordia below. Buds arise so precociously in the axils of the primordia that the apex appears to be producing double structures, the so-called "double ridges". The buds rapidly develop into lateral spikelets but the subtending leaf primordia remain rudimentary. After producing some 20–25 such primordia, the apex initiates the glumes and lemmas of the terminal spikelet, still continuing the same distichous sequence. Occasional deviations from the normal pattern of development seem to be the cause of some of the abnormal inflorescences which may be found: for example, the leaf primordium subtending the lowest lateral spikelet may grow out into a small foliage leaf, or the buds may grow out into side heads instead of single spikelets, or the spikelets may become abnormally elongated. Other abnormalities, such as "banana" twin spikelets and Y-forked heads are less easily "explained". The morphology of still unreported abnormalities can probably be predicted. The relative rarity of freak heads spotlights the stability of growth correlation which is achieved during the morphogenesis of normal inflorescences.

scholarly journals Extended expression of MaKN1 contributes to the leaf morphology in aquatic forms of Myriophyllum aquaticum

Botany ◽  
2015 ◽  
Vol 93 (9) ◽  
pp. 611-621
Author(s):  
M.D. Shafiullah ◽  
Christian R. Lacroix
Keyword(s):  
Apical Meristem ◽  
Leaf Morphology ◽  
Expression Patterns ◽  
Homeobox Gene ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Myriophyllum Aquaticum ◽  
Knox Gene ◽  
Leaf Morphogenesis

Myriophyllum aquaticum (Vell.) Verdc. is heterophyllous in nature with highly dissected simple leaves consisting of several lobes. KNOX (KNOTTED1-LIKE HOMEOBOX) genes are believed to have played an important role in the evolution of leaf diversity. Up-regulation of KNOX during leaf primordium initiation can lead to leaf dissection in plants with simple leaves and, if overexpressed, can produce ectopic meristems on leaves. A previous study on KNOX gene expression in the aerial form of this species showed that this gene is expressed in the shoot apical meristem (SAM), as well as in leaf primordia P0 to P8. Based on these results, it was hypothesized that the prolonged expression of the MaKN1 (Myriophyllum aquaticum Knotted1-like homeobox) gene beyond P8, might play an important role in the generation of more lobes, longer lobes, and hydathode formation in the aquatic leaves of M. aquaticum. The technique of in situ hybridization was carried out using a previously sequenced 300 bp fragment of MaKN1 to determine the expression patterns of this gene in the shoot of aquatic forms of the plant. Expression patterns of MaKN1 revealed that the SAM and leaf primordia of aquatic forms of M. aquaticum at levels P0 (youngest) to P4 were distributed throughout these structures. The level of expression of this MaKN1 gene progressively became more localized to lobes in older leaf primordia (levels P5 to P12). Previous studies of aerial forms of this plant showed MaKN1 expression until P8. Our results with aquatic forms show that the highly dissected leaf morphology in aquatic forms was the result of the prolonged expression of MaKN1 beyond P8. This resulted in the formation of elongated and slightly more numerous lobes, and hydathodes in aquatic forms. These findings support the view that KNOX genes are important developmental regulators of leaf morphogenesis and have played an important role in the evolution of leaf forms in the plant kingdom.

Phyllotaxis of the palm Euterpe oleracea Mart. at the level of the shoot apical meristem

Botany ◽  
2010 ◽  
Vol 88 (5) ◽  
pp. 528-536 ◽  
Author(s):  
Denis Barabé ◽  
Laura Bourque ◽  
Xiaofeng Yin ◽  
Christian Lacroix
Keyword(s):  
Shoot Apical Meristem ◽  
Fundamental Theorem ◽  
Apical Meristem ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Divergence Angle ◽  
Euterpe Oleracea ◽  
The Mean ◽  
The Relationship ◽  
Euterpe Oleracea Mart

Previous studies on palm phyllotaxis deal mainly with the mature trunk. The goals of this study are (i) to determine the relationship between the number of parastichies, the divergence angle, and the plastochrone ratio at the level of the shoot apical meristem; (ii) to examine whether there are fluctuations in the divergence angle; (iii) to interpret the significance of phyllotactic parameters with respect to the mode of growth of the apex. The tubular base of the leaf primordium is more or less asymmetrical, and completely surrounds the shoot apical meristem. The phyllotactic system corresponds to a (2, 3) conspicuous parastichy pair. The mean divergence angle per apex varies between 126.9° ± 9.3° (mean ± SD) and 135. 8° ± 8.0°. Divergence angles for all apices fluctuate within a range of 115.89° to 157.33°. The mean plastochrone ratios between apices varies from 1.35 ± 0.18 to 1.58 ± 0.12. The plastochrone ratio at each plastochrone for all apices ranges from 1.09 to 2.00. There is no correlation between the angle of divergence and the plastochrone ratio. There is a fluctuation in the value of the divergence angle that falls within the range predicted by the fundamental theorem of phyllotaxis. The high value of the ratio of the diameter of leaf primordia over the diameter of the apex, and the long plastochrone might explain the lack of correlation between certain phyllotactic parameters.

A fate map of the Arabidopsis embryonic shoot apical meristem

Development ◽  
1992 ◽  
Vol 115 (3) ◽  
pp. 745-753 ◽  
Author(s):  
V. F. Irish ◽  
I. M. Sussex
Keyword(s):  
Shoot Apical Meristem ◽  
Apical Meristem ◽  
Histological Analysis ◽  
Cell Number ◽  
Leaf Primordia ◽  
Axillary Buds ◽  
Fate Map ◽  
Seed Embryo ◽  
Sector Analysis ◽  
Pale Green

We have mapped the fate of cells in the Arabidopsis embryonic shoot apical meristem by irradiating seed and scoring the resulting clonally derived sectors. 176 white, yellow, pale green or variegated sectors were identified and scored for their position and extent in the resulting plants. Most sectors were confined to a fraction of a leaf, and only occasionally extended into the inflorescence. Sectors that extended into the inflorescence were larger, and usually encompassed about a third to a half of the inflorescence circumference. We also find that axillary buds in Arabidopsis are clonally related to the subtending leaf. Sections through the dry seed embryo indicate that the embryonic shoot apical meristem contains approximately 110 cells in the three meristematic layers prior to the formation of the first two leaf primordia. The histological analysis of cell number in the shoot apical meristem, in combination with the sector analysis have been used to construct a map of the probable fate of cells in the embryonic shoot apical meristem.

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.

scholarly journals Morphological Study of the Structure and Development of Longan Inflorescence

2005 ◽  
Vol 130 (6) ◽  
pp. 793-798
Author(s):  
Miki Nakata ◽  
Nobuo Sugiyama ◽  
Tanachai Pankasemsuk
Keyword(s):  
Morphological Study ◽  
Floral Induction ◽  
Leaf Primordia ◽  
Cool Season ◽  
Developmental Patterns ◽  
Apical Meristems ◽  
Naked Eye ◽  
Foliage Leaf ◽  
Dimocarpus Longan ◽  
Terminal Shoot

The structure and developmental patterns of inflorescence of longan (Dimocarpus longan Lour.) were studied microscopically and by the naked eye. In inflorescence of longan, compound dichasia are arranged on three to four orders of monopodial axes without the formation of terminal flowers, indicating that longan inflorescence is pleiothyrse; cymose partial inflorescences are arranged on more than two monopodial axes. Most of the monopodial axes had differentiated by the end of November just before the cool season. The first sign of inflorescence formation was the appearance of bract primordia at apical meristems of the preformed monopodial axes, with lateral axes preceding the main axes. Dichasia were formed in the axils of bract primordia, and the formation of bracts and dichasia continued. Bract appearance can be detected by the naked eye 1 week after microscopically detected bract appearance. Shoots with intermediate characteristics between the inflorescence and the vegetative shoots were formed; dichasia were formed on the lateral axes, but not on the main axes in intermediate shoots. These results suggest that apical meristems on the terminal shoot produce monopodial axes, together with foliage leaf primordia, before floral induction, but produce bract primordia and compound dichasia, which are composed of sympodial axes, after floral induction.

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.

Sign in / Sign up

Export Citation Format

Share Document