Shoot ontogeny in Arctostaphylos uva-ursi (bearberry): origin and early development of lateral vegetative and floral buds

1984 ◽  
Vol 62 (9) ◽  
pp. 1933-1939 ◽  
Author(s):  
W. R. Remphrey ◽  
T. A. Steeves
Keyword(s):  
Early Development ◽  
Shoot Apex ◽  
Developmental Study ◽  
Vegetative Shoot ◽  
Leaf Base ◽  
Flower Buds ◽  
Foliage Leaf ◽  
Lateral Bud ◽  
Vegetative Shoot Apex ◽  
Bud Initiation

In the course of a general developmental study of Arctostaphylos uva-ursi (L.) Spreng. (bearberry), observations were made on the pattern of lateral bud initiation and development. Three types of foliar organs (foliage leaves, transitional leaves, and bud scales) are initiated by a vegetative shoot apex each year in a predictable sequence. A robust bud, initiated as a detached meristem and delimited by a shell zone, developed in the axil of each foliage leaf. Smaller, poorly developed buds, sometimes arising from tissues of the leaf base, developed in transitional-leaf axils, but they rarely persisted. Although scale axils seldom contained buds, there was evidence to suggest that buds may have started to form but soon became arrested. In the development of an inflorescence, small bracts were initiated by the terminal apex instead of foliage leaves or cataphylls. Flower buds were then initiated in the axils of the bracts and the terminal apex became inactive. The relative roles of shoot apex and subtending leaf primorida in regulating the development of buds are discussed.

Ontogenetical and experimental studies of the floral apex of Portulaca grandiflora. 1. Histology of transformation of the shoot apex into the floral apex

1969 ◽  
Vol 47 (1) ◽  
pp. 133-140 ◽  
Author(s):  
Siti Raswati Soetiarto ◽  
Ernest Ball
Keyword(s):  
Shoot Apex ◽  
Experimental Studies ◽  
Floral Meristem ◽  
Vegetative Shoot ◽  
Floral Organs ◽  
Mature Flower ◽  
Floral Apex ◽  
Portulaca Grandiflora ◽  
Floral Primordia ◽  
Vegetative Shoot Apex

The vegetative apex was a low dome consisting of two layers of tunica surmounting a very small corpus. Foliar primordia originated as periclines in the flanks of T2. The transition apex became first a steep cone and then a hemisphere. All floral primordia—the two bracts, the two sepals, the several whorls of petals, the several whorls of stamens, and the carpels—originated in the manner of leaves, as periclines in T2 on the flanks of the apex. All appendages, including carpels, were therefore lateral. In the early transition, the apex had a brief stage in which there were three tunica layers, but the inner one was lost with the onset of the sepals. The bracts and the first sepal continued the normal positions of primordia for the vegetative phyllotaxy of 3/8, but with the second sepal, this phyllotaxy was lost, and petals, stamens, and carpels were produced in whorls. While leaves, bracts, sepals, and petals were produced in acropetal sequence, stamens were produced in basipetal sequence, and carpels appeared simultaneously. After carpels were formed, the rest of the floral apex underwent a brief period of expansion growth, achieving a diameter comparable to that of a shoot apex, but its substance was eventually incorporated into the carpel margins, which later produced the ovules. This agrees with the determinate nature of the floral apex. During the development of the first series of floral organs, the floral apex underwent continued increase in area, finally achieving a diameter several times that of the vegetative shoot apex. Its size and form were such that they were compared to those of some inflorescence apices. After development of the first series of floral organs, the subjacent tissues to the floral meristem underwent divisions and elongation at right angles to the axis, causing at first a flattening of the meristem, and eventually a cup-shaped form, with the carpels attached in the bottom of a bowl. The mature flower was thus perigynous, but this development arose quite differently from the perigyny as it is known from ontogenetic studies in the Rosaceae.

The shoot apex and the ontogeny of axillary buds in Cuminum cyminum L

1969 ◽  
Vol 17 (2) ◽  
pp. 241 ◽  
Author(s):  
JJ Shah ◽  
K Unnikrishnan
Keyword(s):  
Shoot Apex ◽  
Peripheral Zone ◽  
Axillary Bud ◽  
Vegetative Shoot ◽  
Apical Position ◽  
Leaf Initiation ◽  
Axillant Leaf ◽  
Meristematic Activity ◽  
Vegetative Shoot Apex ◽  
The One

The structure and plastochronic changes of the shoot apex, and the origin, development, procambialization, and vascular relationships of the axillary bud in Cuminum cyminium were investigated. Pre-leaf initiation, leaf initiation, and post-leaf initiation phases of the shoot apex are identified. The inflorescence is axillary. During flowering the main vegetative shoot apex is semispherical, stratified, and devoid of any distinction between the central and peripheral zones. The vegetative axillary bud is differentiated from the peripheral zone of the shoot apex at the second node. It is delimited by an arcuate shell zone which helps in changing the apical position of the bud to foliar. The emergence of the bud is effected by the meristematic activity of tunica and corpus cells. A single prophyll is formed at right angles to the axillant leaf. Usually the bud trace procambium is differentiated during prophyll initiation. Occasionally it may be seen earlier, but not in connection with the earliest visible bud meristem. There are four to six strands of the bud trace directly interconnecting not only the strands of the prophyll and axillant leaf traces but also those of the second or sometimes even the third bud leaf and the axillant leaf. The bud trace procambial connection is formed by basipetal and acropetal differentiation of procambium in which the bud meristem cells and vacuolated ground meristem cells below the bud are involved. The cells of the peripheral zone of the bud apex below the prophyll primordium procambialize in a basipetal direction. As a continuation from the strand of the axillant leaf trace, the adjacent vacuolated ground meristem cells below the bud acropetally differentiate into procambial cells in the direction of the basipetal procambium and they make connection with it. All the strands of the bud trace are not simultaneously developed. The vegetative and inflorescence buds show varying vascular relationships between the strands of the leaf traces and those of the bud traces. The node differentiated during the vegetative phase of the plant is trilacunar and the one formed at flowering time is tetra- or pentalacunar. The nature and number of bud trace strands, however, suggest fundamental similarities between vegetative and inflorescence buds.

scholarly journals The forever young gene encodes an oxidoreductase required for proper development of the Arabidopsis vegetative shoot apex

1994 ◽  
Vol 6 (6) ◽  
pp. 835-847 ◽  
Author(s):  
Joseph D. Callos ◽  
Marion DiRado ◽  
Bibo Xu ◽  
Friedrich J. Behringer ◽  
Bruce M. Link ◽  
...  
Keyword(s):  
Shoot Apex ◽  
Vegetative Shoot ◽  
Vegetative Shoot Apex ◽  
Young Gene

Normal and Abnormal Development in the Arabidopsis Vegetative Shoot Apex

1992 ◽  
Vol 4 (6) ◽  
pp. 631 ◽  
Author(s):  
June I. Medford ◽  
Friedrich J. Behringer ◽  
Joseph D. Callos ◽  
Kenneth A. Feldmann
Keyword(s):  
Shoot Apex ◽  
Abnormal Development ◽  
Vegetative Shoot ◽  
Vegetative Shoot Apex
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