Ontogeny of the Primary Thickening Meristem in Seedlings of Bougainvillea spectabilis

Stevenson, Dennis; Popham, Richard A.

doi:10.2307/2441317

Cited by 21 publications

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“…Secondary phloem and xylem can differentiate on opposite sides of the PTM, at isolated locations, in newly produced conjunctive tissue. The cambium of desmogen strands is referred to as a desmagic cambium (Stevenson and Popham, 1973).…”

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confidence: 99%

“…63 Mirskaja (1929/1930, Maheshwari (1930), Hamner (1938), Inouye (1956), Balfour (1965), Studholme and Philipson ( 1966), and Kato (1963) . Only one investigation has dealt with complete ontogenetic development of the PTM in a dicotyledonous plant (Stevenson and Popham, 1973), and no study of the effects of photoperiod on PTM development in dicotyledons has been published. Results of investigations by various workers will be described using our terminology.…”

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confidence: 99%

“…Inability to locate the PTM is due to anastomosing of prodesmogen strands and procambial strands, which disrupts the continuity of the PTM. DISCUSSION-We have used the term prodesmogen to refer to the strand of meristematic cells differentiating in newly produced conjunctive tissue, and, following differentiation of xylem and phloem in the strand, we use the term desmogen strand (Stevenson and Popham, 1973). Prodesmogen strands have been referred to as the procambial ring (Louis, 1935;Gregoire, 1934), and the secondary desmogen (Scott and Brebner, 1893).…”

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Ontogeny and Correlative Relationships of the Primary Thickening Meristem in Four-O'Clock Plants (Nyctaginaceae) Maintained Under Long and Short Photoperiods

Mikesell¹,

Popham²

1976

American Journal of Botany

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The developmental anatomy of Mirabilis jalapa was investigated during the first 90 days of growth. The primary thickening meristem (PTM) initially differentiates in the pericycle at the top of the cotyledonary node 18 days after germination, then basipetally in the pericycle through the hypocotyl. The PTM differentiates acropetally into the stem and in the pericycle of the primary root, commencing 22 days after germination. Endodermis is easily identifiable in hypocotyls as well as in primary roots because of Casparian thickenings in its cells. It has not been definitely identified in stems. There are three rings of primary vascular bundles in the stem. The PTM differentiates as segments of cambium in a layer of cells (probably in the pericycle) on an arc between vascular bundles of the outer bundle ring. Later, arcs of PTM differentiate externally to the phloem of each bundle. Each arc forms a connection between original segments of PTM lying on either side of each vascular bundle. Thus, the PTM becomes a continuous cylinder. The PTM differentiates in the pericycle outside vascular tissue in the hypocotyl and root. Differentiation of the PTM and the mode of secondary thickening is similar in plants exposed to short (8-hr) and to long (l8-hr) photoperiods, but some differences were observed. The PTM differentiates closer to the stem apex in all plants over 18 days of age growing vegetatively under long photoperiods. That is, the diffuse lateral meristem, in whose cells the PTM differentiates in young internodes, is shorter in nearly all investigated plants growing in long photoperiods. The hypocotyl and base of the primary root of 40-dayold plants in short photoperiods were more enlarged than those of the same age plants in long photoperiods; but, at the end of 64 days, the hypocotyl and primary root base were larger in plants growing under short photoperiods. Thirty-four days after seed germination, flower initiation occurs in plants exposed to short photoperiods. One hundred fifty days after seed germination, flowers differentiate on plants exposed to long photoperiods. 427

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Ontogeny and Correlative Relationships of the Primary Thickening Meristem in Four-O'Clock Plants (Nyctaginaceae) Maintained Under Long and Short Photoperiods

Mikesell¹,

Popham²

1976

American Journal of Botany

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“…In this respect, Bougainvillea spectabilis is similar to monocotyledons. However, in this nyctaginaceous species there are nodal anastomoses between veins of the inner and outer systems (Stevenson and Popham, 1973). Such a feature is not seen in the inflorescence axis of Andropogon gerardii and I could find no clear statement that such a condition occurs in other monocotyledons.…”

Section: Development Of the Vascular System-mentioning

confidence: 69%

“…The situation in the Nytaginaceae is not so clear. The outer bundles, at least in Bougainvillea spectabilis, are smaller than the inner and apparently develop later (Stevenson and Popham, 1973). In this respect, Bougainvillea spectabilis is similar to monocotyledons.…”

Section: Development Of the Vascular System-mentioning

confidence: 90%

The Vascular System of the Inflorescence Axis of Andropogon Gerardii (Gramineae) and Its Bearing on Concepts of Monocotyledon Vascular Tissue

Maze

1977

American J of Botany

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The vascular bundles in the inflorescence axis of Andropogon gerardii occur in inner and outer systems. The inner system is made up of large, early developing strands that, at earliest stages of development, are precocious (= the appendage they are to serve has not yet been initiated). The outer system consists of later developing smaller strands that are open ended in a proximal direction (= strands differentiate basipetally in the cortex below the appendage they serve). Bundles of both the inner and outer systems are not connected to other procambium early in their development but exist as isolated strands. The veins of the inner system of the inflorescence axis occur as sympodia. The presence of inner and outer systems in the vascular tissue is common to most monocotyledons. However, amongst monocotyledons, only certain grasses have been shown to have strands of the inner system that are isolated early in development. Many dicotyledons have large strands which are precocious and some have smaller, later developing strands which are open ended in a proximal direction, hence they occur as isolated strands. These smaller strands in dicotyledons occur between large strands. Certain dicotyledons have an inner and an outer system of veins. Of these, some have veins of the inner system that differ from the inner system bundles of monocotyledons in that they also form part of the outer system of veins, or develop at a different time. One other dicotyledon with an inner and outer system, Bougainvillea, differs from monocotyledons only in that the bundles of the outer system do not seem to be isolated early in their development and anastomoses are seen between the inner and outer systems. Thus, it appears that monocotyledons differ from dicotyledons only in the presence of independent inner and outer systems of vascular bundles in the former. Thus, the hypothesis of Zimmermann and Tomlinson that there are basic differences between monocotyledon and dicotyledon vascular systems is not substantiated. It is even suspected that monocotyledon and dicotyledon vascular systems will be demonstrated to be modifications of a basic plan consisting of large, acropetally differentiating and smaller, basipetally differentiating strands.

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Diversity, distribution, development, and evolution of medullary bundles in Nyctaginaceae

Neto

Pace

Douglas

et al. 2020

American J of Botany

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Premise Medullary bundles, i.e., vascular units in the pith, have evolved multiple times in vascular plants. However, no study has ever explored their anatomical diversity and evolution within a phylogenetic framework. Here, we investigated the development of the primary vascular system within Nyctaginaceae showing how medullary bundles diversified within the family. Methods Development of 62 species from 25 of the 31 genera of Nyctaginaceae in stem samples was thoroughly studied with light microscopy and micro‐computed tomography. Ancestral states were reconstructed using a maximum likelihood approach. Results Two subtypes of eusteles were found, the regular eustele, lacking medullary bundles, observed exclusively in representatives of Leucastereae, and the polycyclic eustele, containing medullary bundles, found in all the remaining taxa. Medullary bundles had the same origin and development, but the organization was variable and independent of phyllotaxy. Within the polycyclic eustele, medullary bundles developed first, followed by the formation of a continuous concentric procambium, which forms a ring of vascular bundles enclosing the initially formed medullary bundles. The regular eustele emerged as a synapomorphy of Leucastereae, while the medullary bundles were shown to be a symplesiomorphy for Nyctaginaceae. Conclusions Medullary bundles in Nyctaginaceae developed by a single shared pathway, that involved the departure of vascular traces from lateral organs toward the pith. These medullary bundles were encircled by a continuous concentric procambium that also constituted the polycyclic eustele, which was likely a symplesiomorphy for Nyctaginaceae with one single reversion to the regular eustele.

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Ontogeny of the Primary Thickening Meristem in Seedlings of Bougainvillea spectabilis

Cited by 21 publications

References 0 publications

Ontogeny and Correlative Relationships of the Primary Thickening Meristem in Four-O'Clock Plants (Nyctaginaceae) Maintained Under Long and Short Photoperiods

Ontogeny and Correlative Relationships of the Primary Thickening Meristem in Four-O'Clock Plants (Nyctaginaceae) Maintained Under Long and Short Photoperiods

The Vascular System of the Inflorescence Axis of Andropogon Gerardii (Gramineae) and Its Bearing on Concepts of Monocotyledon Vascular Tissue

Diversity, distribution, development, and evolution of medullary bundles in Nyctaginaceae

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