SECONDARY GROWTH IN THE STEM OF SOME SPECIES OF ALTERNANTHERA AND ACHYRANTHES ASPERA (AMARANTHACEAE)

IAWA Journal ◽  
2000 ◽  
Vol 21 (4) ◽  
pp. 417-424 ◽  
Author(s):  
Kishore S. Rajput ◽  
K.S. Rao
Keyword(s):  
Secondary Growth ◽  
Sieve Tube ◽  
Axial Parenchyma ◽  
Achyranthes Aspera ◽  
Companion Cells ◽  
Cambial Variant ◽  
Mother Cells

Secondary growth in Achyranthes aspera, Alternanthera polygamous, A. pungens, A. sessilis, and A. triandra was achieved by the development of a cambial variant resulting in successive rings of xylem and phloem. Each new cambium was developed at a distance about two to three cells external to the phloem produced by the previous cambium. The development of phloem was not synchronous in the species studied. Phloem development started either simultaneously with xylem or after the formation of a few xylem derivatives. In Achyranthes, xylem production started first followed by the development of phloem. Phloem mother cells differentiated into sieve tube elements, companion cells and axial parenchyma. Xylem was storied and exclusively composed of axial elements. Radial elements were absent in all the xylem rings of the stem. Vessels were angular and mostly solitary, but radial and tangential multiples were also observed occasionally. Xylem fibres were nonseptate and nucleated. Development of phloem and the rayless nature of the xylem is discussed.

Structure of Stem and Cambial Variant in Spatholobus Roxburgii (Leguminosae)

IAWA Journal ◽  
1993 ◽  
Vol 14 (2) ◽  
pp. 191-204 ◽  
Author(s):  
M.N.B. Nair
Keyword(s):  
Vascular Tissue ◽  
Secondary Growth ◽  
Sieve Tube ◽  
Secretory Cells ◽  
Secondary Phloem ◽  
Phloem Parenchyma ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Ray Cells ◽  
Cambial Variant

The stern of Spatholobus roxburghii, a tropicalliana, has alternating layers of xylem and phloem as a result of formation and activity of successive cambia. Successive cambial rings are developed by dedifferentiation of groups of parenchyma cells outside the discontinuous band of sclereid-fibres. The sclereid- fibre band is formed by the development of sclereids between the primary bark fibres. Each successive cambium first produces a layer of sclereid-fibres which separates the vascular tissue produced by one cambial ring from the other. After secondary growth, the epidermis is replaced by periderm. In the older stern phelloderm contributes to the formation of new cambiallayers. Secondary phloem has sieve tube members; companion cells, phloem parenchyma, phloem fibres and secretory cells. The wood shows a tendency towards ring-porosity only in the first xylem layer. The subsequent layers are diffuseporous. The vessels are wide and narrow. Perforated ray cells or radial vessels are frequent in the wood and probably help in vertical conduction by interconnecting vessel endings. In this scandent species parenchyma cells are abundant. It is inferred that they help the vessel segments to remain undamaged when the woody stern twists around supports.

Structure and ontogeny of the fissured stems of Callaeum (Malpighiaceae)

IAWA Journal ◽  
2017 ◽  
Vol 38 (1) ◽  
pp. 49-66 ◽  
Author(s):  
Pablo A. Cabanillas ◽  
Marcelo R. Pace ◽  
Veronica Angyalossy
Keyword(s):  
Secondary Xylem ◽  
Vascular System ◽  
Secondary Growth ◽  
Natural Fracture ◽  
Production Rates ◽  
Axial Parenchyma ◽  
Parenchyma Cells ◽  
Ray Cells ◽  
Cambial Variant ◽  
Stem Development

Stem ontogeny and structure of two neotropical twining vines of the genus Callaeum are described. Secondary growth in Callaeum begins with a typical regular cambium that gradually becomes lobed as a result of variation in xylem and phloem production rates in certain portions of the stem aligned with stem orthostichies. As development progresses, lignified ray cells of the initially formed secondary xylem detach on one side from the adjacent tissues, forming a natural fracture that induces the proliferation of both ray and axial nonlignified parenchyma. At the same time, parenchyma proliferation takes place around the pith margin and generates a ring of radially arranged parenchyma cells. The parenchyma generated in this process (here termed disruptive parenchyma) keeps dividing throughout stem development. As growth continues, the parenchyma finally cleaves the lignified axial parts of the vascular system into several isolated fragments of different sizes. Each fragment consists of xylem, phloem and vascular cambium and is immersed in a ground matrix of disruptive parenchyma. The cambium present in each fragment divides anticlinally to almost encircle each entire fragment and maintains its regular activity by producing xylem to the centre of the fragment and phloem to the periphery. Additionally, new cambia arise within the disruptive parenchyma and produce xylem and phloem in various polarities, such as xylem to the inside and phloem to the outside of the stem, or perpendicularly to the original cambium. Unlike the very distinctive stem anatomical architecture resulting from this cambial variant in Callaeum, its secondary xylem and phloem exhibit features typical of lianas. These features include very wide conducting cells, abundant axial parenchyma, high and heterocellular rays and gelatinous fibres.

Structure of Wood and Cambial Variant in the Stem of Dalbergia Paniculata Roxb.

IAWA Journal ◽  
1990 ◽  
Vol 11 (4) ◽  
pp. 379-391 ◽  
Author(s):  
M. N. B. Nair ◽  
H. Y. Mohan Ram
Keyword(s):  
Succinate Dehydrogenase ◽  
Dehydrogenase Activity ◽  
Sieve Tube ◽  
Secondary Phloem ◽  
Succinate Dehydrogenase Activity ◽  
Successive Cambia ◽  
Phloem Parenchyma ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Cambial Variant

The wood of Dalbergia paniculata is unique as it consists of concentric layers of broad xylem, alternating with bands of narrow phloem. This anomaly results from the periodic formation of successive cambia in the secondary phloem. Some phloem parenchyma cells dedifferentiate to form a discontinuous ring of cambium. Such parenchyma cells have higher succinate dehydrogenase activity than the neighbouring cells of secondary phloem. The newly differentiated cambial layer functions bidirectionally, and its products give rise to xylem internally and phloem externally. The phloem along with cambium present internal to the newly formed xylem becomes included.The wood is diffuse-porous and the intervessel pits are vestured. The phloem has welldifferentiated sieve tube members and companion cells.

Structure of the secondary xylem and development of a cambial variant in Serjania mexicana (Sapindaceae)

IAWA Journal ◽  
2021 ◽  
pp. 1-11
Author(s):  
Kishore S. Rajput ◽  
Amit D. Gondaliya ◽  
Roger Moya
Keyword(s):  
Secondary Xylem ◽  
Secondary Growth ◽  
Stem Anatomy ◽  
The Family ◽  
Ray Cells ◽  
Cambial Variant ◽  
Proportional Increase ◽  
Plant Families ◽  
Ray Parenchyma Cells ◽  
Cambial Variants

Abstract The lianas in the family Sapindaceae are known for their unique secondary growth which differs from climbing species in other plant families in terms of their cambial variants. The present study deals with the stem anatomy of self-supporting and lianescent habit, development of phloem wedges, the ontogeny of cambial variants and structure of the secondary xylem in the stems of Serjania mexicana (L.) Willd. Thick stems (15–20 mm) were characterized by the presence of distinct phloem wedges and tangentially wide neo-formed cambial cylinders. As the stem diameter increases, there is a proportional increase in the number of phloem wedges and neo-formed vascular cylinders. The parenchymatous (pericyclic) cells external to phloem wedges that are located on the inner margin of the pericyclic fibres undergo dedifferentiation, become meristematic and form small segments of cambial cylinders. These cambia extend tangentially into wide and large segments of neoformations. Structurally, the secondary xylem and phloem of the neo-formed vascular cylinders remain similar to the derivatives produced by the regular vascular cambium. The secondary xylem is composed of vessels (wide and narrow), fibres, axial and ray parenchyma cells. The occurrence of perforated ray cells is a common feature in both regular and variant xylem.

scholarly journals Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton & Rose, Stephanocereus A. Berger and Brasilicereus Backeberg

2007 ◽  
Vol 21 (4) ◽  
pp. 813-822 ◽  
Author(s):  
Patricia Soffiatti ◽  
Veronica Angyalossy
Keyword(s):  
Secondary Xylem ◽  
Sieve Tube ◽  
Vascular Bundles ◽  
Campos Rupestres ◽  
Espinhaço Range ◽  
Diagnostic Characters ◽  
Bordered Pits ◽  
Companion Cells ◽  
Southern Bahia ◽  
Perforation Plates

(Anatomy of Brazilian Cereeae (subfamily Cactoideae, Cactaceae): Arrojadoa Britton & Rose, Stephanocereus A. Berger wâBrasilicereus Backeberg). Arrojadoa, Stephanocereus and Brasilicereus are endemic Brazilian Cereeae, occurring along the Espinhaço Range, in the campos rupestres, cerrados and caatingas, from northern Minas Gerais to southern Bahia. The genera are columnar, erect to semi-erect cacti, except for one species, A bahiensis, which is globose. This study describes the anatomy of dermal, fundamental and vascular systems, aiming to find diagnostic characters for the genera and species. Basal portions of stems were sectioned transversely and longitudinally, and stained with Astrablue and Safranin. The species share a uniseriate epidermis, with thick cuticle; well developed collenchymatic hypodermis, containing prismatic crystals; cortex with numerous mucilage cells, druses and vascular bundles; outside cortex as a palisade parenchyma; periderm composed of lignified cork cells alternating with suberized cells; pheloderm consisting of a few layers of thin-walled cells; phloem composed of solitary or multiple of two to three sieve tube elements, companion cells, axial and radial parenchyma; secondary xylem with solitary to multiple vessels, with simple perforation plates and alternate bordered to semi-bordered pits; axial parenchyma scanty vasicentric to incomplete; libriform septate fibres; large rays. Unlignified parenchyma is seen in the secondary xylem, varying from a few cells to bands among axial and radial elements. The following are considered diagnostic characters: the shape of lignified phellem cells, cubic to radially elongate, which individualizes S. leucostele; an underdeveloped hypodermis and the occurrence of sclereids in the cortex are exclusive to Brasilicereus markgrqfii.

The secondary phloem of Austrobaileya scandens

1970 ◽  
Vol 48 (2) ◽  
pp. 341-359 ◽  
Author(s):  
Lalit M. Srivastava
Keyword(s):  
Tannic Acid ◽  
Cross Sections ◽  
Significant Proportion ◽  
Sieve Tube ◽  
Secondary Phloem ◽  
Sieve Elements ◽  
Sieve Cells ◽  
Companion Cells ◽  
Parenchyma Cells ◽  
Definition Of

The origin of sieve elements and parenchyma cells in the secondary phloem of Austrobaileya was studied by use of serial cross sections stained with tannic acid – ferric chloride and lacmoid. In three important respects, Austrobaileya phloem recalls gymnospermous features: it has sieve cells rather than sieve-tube members; a significant proportion of sieve elements and companion cells arise independently of each other; and sieve areas occur between sieve elements and companion cells ontogenetically unrelated to each other. The angiospermous feature includes origin of most sieve elements and parenchyma, including companion cells, after divisions in phloic initials. In these instances companion cells show a closer ontogenetic relationship to sieve elements than do other parenchyma cells. The combination of gymnospermous and angiospermous features makes phloem of Austrobaileya unique when compared to that of all those species that have been investigated in detail. It is further suggested that the term albuminous cells is inappropriate and should be replaced by companion cells but that the ontogenetic relationship implicit in the definition of companion cells is too restrictive and should be abandoned.

Comparative Structure Of Vascular Cambium And Its Derivatives In Some Species Of Sterculia

IAWA Journal ◽  
1996 ◽  
Vol 17 (3) ◽  
pp. 311-318 ◽  
Author(s):  
K. S. Rao ◽  
Kishore S. Rajput ◽  
T. Srinivas
Keyword(s):  
Sieve Tube ◽  
Vascular Cambium ◽  
The South ◽  
Structural Variations ◽  
Axial Parenchyma ◽  
Vessel Elements ◽  
Comparative Structure ◽  
The Mean ◽  
Cambial Cells ◽  
Sheath Cells

Structural variations in cambium, xylem and phloem collected from main trunks of Sterculia colorata, S. alata, S. villosa, S. urens and S. foetida growing in the South Dangs forests were studied. In all five species, the cambium was storied with variations in the length of fusiform cambial cells. Compared to other species S. foetida had the longest and S. urens the shortest fusiform cambial cells. Cambial rays in all the species were compound (tall) and heterocellular with sheath cells. Their height and width were maximal in S. foetida and in S. villosa respectively. In all the species the storied nature of fusiform cambial cells was maintained in derivative cells that developed into sieve tube elements; vessel elements and axial parenchyma of both phloem and xylem. However, fibres of phloem and xylem were nonstoried. The dimensions of elements in phloem and xylem varied among the species. The variation in the mean length of sieve tube elements and vessel members coincided with that of fusiform cambial cells.

Qualitative Structural Changes during Bark Development in Quercus Robur, Ulmus Glabra, Populus Tremula and Betula Pendula

IAWA Journal ◽  
1991 ◽  
Vol 12 (1) ◽  
pp. 5-22 ◽  
Author(s):  
M. Trockenbrodt
Keyword(s):  
Quercus Robur ◽  
Betula Pendula ◽  
Structural Changes ◽  
Secondary Growth ◽  
Sieve Tube ◽  
Populus Tremula ◽  
Ulmus Glabra ◽  
Phloem Fibre ◽  
Second Year ◽  
Bark Structure

The development of bark structure of Quercus robur L., Ulmus glabra Huds., Populus tremula L. and Betula pendula Roth is being described. Profound structural changes can be observed during the first years after secondary growth has started. In all four species the epidermis is replaced by a periderm, the cortex shows intensive dilatation growth, and the groups of primary bark fibres are pushed apart. The collapse of sieve tube members starts with the second year. With proceeding secondary growth, the specific formation of sclerenchymatic tissue, especially sclereids, and the dilatation growth are processes which strongly affect the bark structure of Quercus robur, Populus tremula and Betula pendula. In addition, wide, fused phloem rays develop in Quercus robur. The structure of Ulmus glabra bark is affected by the formation of phloem fibre-/sclereid-like cells and mucilage cells and by dilatation growth. The histological pattern of Ulmus glabra bark stabilises to a great extent after the first few years, the other barks investigated show further developmental processes over many years. In all species the formation of a rhytidome is the last distinct modification of bark structure.

WOOD ANATOMY OF THE TRIBE MILLETTIEAE WITH COMMENTS ON RELATED PAPILIONOID LEGUMINOSAE

IAWA Journal ◽  
2004 ◽  
Vol 25 (4) ◽  
pp. 485-545 ◽  
Author(s):  
Peter Gasson ◽  
Elspeth Wray ◽  
Brian D. Schrire
Keyword(s):  
Wood Anatomy ◽  
Secondary Growth ◽  
Molecular Data ◽  
Sensu Stricto ◽  
Axial Parenchyma ◽  
The Core ◽  
C 23 ◽  
Form Part ◽  
Cladistic Analyses ◽  
Morphological And Molecular Data

The tribe Millettieae has traditionally included some 43 to 47 genera although more recent phylogenetic evidence has shown that a smaller core-Millettieae group of c. 23 genera may form part of a recircumscribed Millettieae sensu stricto. We have examined the wood of 27 genera, 16 of which are in the core-Millettieae and the remaining 11 belong in 4 groups, mostly with closer affinities outside Millettieae s.str. The wood anatomy of the various genera is nevertheless very uniform. Most genera are diffuse porous with no predominant vessel pattern. They have paratracheal parenchyma ranging from scanty through vasicentric, aliform and confluent, and often banded. Rays are mainly up to 5 cells wide. Axial parenchyma and rays are nearly always storied. The lianas Paraderris elliptica, Derris uliginosa, Ostryocarpus cf. riparius and Wisteria spp. have alternating bands of xylem and phloem, which are also found in some Dalbergieae. Even in the genera without such anomalous secondary growth there are many similarities between the wood of Millettieae and Dalbergieae. The wood of some genera in Sophoreae and Swartzieae is also compared. Our observations will be put in the context of recent cladistic analyses on both morphological and molecular data by other authors.

Sieve tube elements in the stem of Neptunia oleracea Lour

1968 ◽  
Vol 16 (3) ◽  
pp. 433 ◽  
Author(s):  
JJ Shah ◽  
MR James
Keyword(s):  
Aquatic Plant ◽  
Sieve Tube ◽  
Sieve Plate ◽  
Callose Deposition ◽  
Nuclear Disintegration ◽  
Full Development ◽  
Companion Cells ◽  
Sieve Plates ◽  
Structural Aspects ◽  
Sieve Tube Element

Some structural aspects of the phloem of Neptunia oleracea, an aquatic plant, are reported. The sieve tube elements on an average are 190μ long and 13μ wide and have compound sieve plates at varying degrees of inclination. The developing sieve tube element has a single large spindle-shaped slime body, which presumably has an outer membrane. The slime body undergoes dispersal before or after full development of the sieve plate, but often nuclear degeneration occurs first. Distinct slime plugs are absent. Plastids and other granular bodies are attached to many of the strands, which are less than 0.5μ in diameter. During the process of nuclear disintegration the nuclear membrane is indistinct, and extruded nucleolus is not observed. Sieve areas and connections are comparatively few in number, and the sieve areas and wall connections as well as the sieve plates show scanty callose deposition. Plastids are abundant in the sieve tube elements, especially near the sieve plates. The companion cells of two consecutive sieve tube elements are placed on alternate sides and hence their longitudinal continuity is not always maintained. Companion cells do not exceed the length of the sieve tube element.

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