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.

The rotated-lamina syndrome. III. Cases in Begonia, Corylus, Magnolia, Pellionia, Prunus, and Tilia

1993 ◽  
Vol 71 (2) ◽  
pp. 229-247 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Leaf Development ◽  
Leaf Blade ◽  
Leaf Primordia ◽  
Leaf Primordium ◽  
Normal Leaf ◽  
Normal Orientation ◽  
Lateral Shoots ◽  
Asymmetric Growth ◽  
Prunus Laurocerasus

The rotated-lamina syndrome occurs in all adult shoots of Tilia × europaea, and in lateral shoots of Corylus spp. and Prunus laurocerasus. Corylus and Prunus also have orthotropic radially symmetrical shoots that have normal leaf orientation. Development of the syndrome in leaf primordia in Tilia and Corylus is similar to that previously described in Ulmus, i.e., the leaf primordium is initially asymmetrical so that the leaf blade component of the primordium arises facing only obliquely towards the shoot apex, and further asymmetrical outgrowth of the leaf buttress brings the leaf blade region into the rotated position. Leaves of Begonia foliosa and the ventral leaves of (anisophyllous) Pellionia pulchra arise from initially symmetrical primordia, and lamina rotation occurs by asymmetric growth at the base of the leaf blade region. The process is similar to that in the woody examples but occurs at a proportionately later stage of leaf development. Development of the syndrome in Prunis laurocerasus and Magnolia × soulangeana differs considerably. Primordia are slightly asymmetrical but have normal dorsiventrality at first, but when the lamina arises the two edges of the leaf blade grow towards the same (upper) side of the bud, and this is responsible for most of the appearance of rotation. In general the upper stipule is initially larger than the lower and arises much earlier in Corylus and Tilia. Leaves that have normal orientation in Corylus and Prunus develop from quite symmetrical primordia, but those of Cotylus may show some asymmetry of stipule development. Shoots of all cases can be considered to show heteroblastic growth, and the early part of the heteroblastic sequence is prolonged in the orthotropic shoots with normally oriented leaves in Corylus and Prunus. The morphological and morphogenetic significance of the rotated-lamina syndrome is discussed. Key words: Begonia, Corylus, Magnolia, Pellionia, Prunus, Tilia, leaf, development, dorsiventrality, lamina rotation.

The rotated-lamina syndrome. V. Partial lamina rotation and related features in Hamamelidaceae

1994 ◽  
Vol 72 (5) ◽  
pp. 626-634 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Key Words ◽  
Shoot Apex ◽  
Leaf Development ◽  
Early Stage ◽  
Leaf Primordia ◽  
Leaf Base ◽  
Early Stages ◽  
Young Leaves

Shoots of Hamamelidaceae have been examined for the presence of the rotated-lamina syndrome, a condition in which young leaves in bud face towards one side of the shoot (normally the upper) rather than towards their own shoot apex. Early leaf development and bud organisation have been examined in representatives of eight genera with dorsiventral shoots and distichous phyllotaxis, and of four genera with radially symmetrical shoots and spiral or decussate phyllotaxis. Radially symmetrical shoots do not show any evidence of the syndrome. The distichous Corylopsis and Hamamelis species studied have leaf primordia that are asymmetrical from an early stage and show partial lamina rotation, the lamina facing obliquely towards the upper side of the bud. Mature laminae are usually asymmetrical. In Corylopsis rotation arises by torsion in the petiole region, and in Hamamelis by asymmetrical growth of the leaf base. Distichous examples without lamina rotation also have asymmetrical primordia in most cases, often have asymmetrical leaves, and all show the same asymmetrical development of the leaf base as found in Hamamelis. It is suggested that these features represent either (i) relics of rotated-lamina syndrome that was present in these cases but has been suppressed or (ii) early stages in evolution of rotated-lamina syndrome. It is suggested that suppression is the more likely interpretation. Corylopsis and Hamamelis may also be in the process of suppressing the syndrome. Key words: Hamamelidaceae, 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.

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.

The rotated-lamina syndrome. IV. Relationships between rotation and symmetry in Magnolia and other cases

1994 ◽  
Vol 72 (1) ◽  
pp. 25-38 ◽  
Author(s):  
W. A. Charlton
Keyword(s):  
Key Words ◽  
Shoot Apex ◽  
Leaf Development ◽  
Leaf Primordia ◽  
The State ◽  
Axillary Buds ◽  
Reverse Direction ◽  
Ulmus Glabra ◽  
Young Leaves

Further variations of the rotated-lamina syndrome are described in Magnolia spp. and Rhamnus imeretinus, as well as an abnormal adult shoot of Ulmus glabra without lamina rotation. All magnolias investigated show lamina rotation, but there are four possible forms of shoot symmetry: (i) dorsiventral distichous shoots with the form of rotated-lamina syndrome previously described, i.e., laminae of young leaves all face towards the same (upper) side of the bud or towards the parental axis in axillary buds; (ii) another form of dorsiventral symmetry in which lamina rotation occurs in the reverse direction; (iii) spiral phyllotaxis with laminae rotated to face up the genetic spiral; and (iv) spiral phyllotaxis with laminae rotated to face down the genetic spiral. Shoot symmetry and development of lamina rotation in leaf primordia correlate with the taxo-nomic subdivision of the genus. Shoots of R. imeretinus are dorsiventral, with leaves arranged in four ranks, and lamina rotation occurs towards the upper side of the shoot. The sense of rotation of leaf primordia reverses with a periodicity of two plastochrons. In the abnormal shoot of Ulmus without lamina rotation, phyllotaxis was distichous and leaf primordia were symmetrical. The various cases are discussed in relation to the previously erected hypothesis that control of development in dorsiventral shoots with the rotated-lamina syndrome resides in alternating states of asymmetry in the shoot apex, and the corollary that a shoot with spiral phyllotaxis and one sense of lamina rotation should result if the state of asymmetry is maintained and does not alternate. Key words: Magnolia spp., Rhamnus imeretinus, Ulmus glabra, leaf, development, dorsiventrality, lamina rotation.

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.

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.

scholarly journals The Diverse Roles of Auxin in Regulating Leaf Development

Plants ◽  
2019 ◽  
Vol 8 (7) ◽  
pp. 243 ◽  
Author(s):  
Yuanyuan Xiong ◽  
Yuling Jiao
Keyword(s):  
Leaf Development ◽  
Leaf Blade ◽  
Recent Progress ◽  
Auxin Transport ◽  
Leaf Primordium ◽  
Auxin Signaling ◽  
Plant Organs ◽  
Leaf Patterning ◽  
Flat Structures ◽  
Photosynthesis And Respiration

Leaves, the primary plant organs that function in photosynthesis and respiration, have highly organized, flat structures that vary within and among species. In recent years, it has become evident that auxin plays central roles in leaf development, including leaf initiation, blade formation, and compound leaf patterning. In this review, we discuss how auxin maxima form to define leaf primordium formation. We summarize recent progress in understanding of how spatial auxin signaling promotes leaf blade formation. Finally, we discuss how spatial auxin transport and signaling regulate the patterning of compound leaves and leaf serration.

Chusquea nedjaquithii (Poaceae: Bambusoideae, Bambuseae, Chusqueinae), a new endemic species from Oaxaca, Mexico

Phytotaxa ◽  
2014 ◽  
Vol 184 (1) ◽  
pp. 23 ◽  
Author(s):  
Eduardo Ruiz-Sanchez ◽  
Teresa Mejía-Saulés ◽  
Lynn G. Clark
Keyword(s):  
Endemic Species ◽  
Leaf Blade ◽  
Herbarium Specimens ◽  
Number Of Species ◽  
Foliage Leaf ◽  
Mexican State ◽  
Sierra Madre ◽  
Sierra Madre Del Sur ◽  
Vegetative Characters

Chusquea is the most diverse among woody bamboo genera, with 174 described species. Not surprisingly, Chusquea is the most diverse bamboo genus in Mexico, and with the description of C. nedjaquithii the number of species will increase to 20, representing almost 45% of the total Mexican woody bamboo diversity. Based on fieldwork in the Mexican state of Oaxaca and revision of herbarium specimens we describe and illustrate C. nedjaquithii, a species endemic to the Sierra Madre del Sur in Oaxaca, Mexico. Chusquea nedjaquithii is similar to C. liebmannii but differs in having culms with deciduous hairs, an oblate central bud and fewer subsidiary buds, strongly geniculate branches in one row forming an incomplete verticil, oblique foliage leaf blade bases, and longer inner ligules in the foliage leaves. A key to the Mexican Chusquea species based on vegetative characters is provided.

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