The continuity of primary and secondary growth in Cordyline terminalis (Agavaceae)

1985 ◽  
Vol 63 (11) ◽  
pp. 1907-1913 ◽  
Author(s):  
Darleen A. DeMason ◽  
Mark. A. Wilson
Keyword(s):  
Vascular System ◽  
Secondary Growth ◽  
Central Cylinder ◽  
Vascular Bundles ◽  
Outer Cortex ◽  
Azure B ◽  
Secondary Thickening ◽  
Radial Extent ◽  
Secondary Tissue ◽  
Wide Zone

The primary thickening meristem in Cordyline terminalis (L.) Kunth was found to be continuous with the secondary thickening meristem in vegetative shoots. This could be seen in longitudinal and transverse sections stained with azure B, aniline blue–black, or safranin and fast green. The primary thickening meristem was a wide zone in the crown, and initial cells were arranged in anticlinal files which were continuous from an area within the central cylinder to the outer cortex. The secondary thickening meristem was narrow in radial extent and consisted of initial cells which were arranged in short, anticlinal files. When vascular bundles were followed (and plotted) acropetally from serial transverse sections starting with groups of anastomosing secondary bundles, secondary bundles were continuous with both major and minor axial primary bundles or with procambial strands. All bundles were collateral in the crown but became amphivasal in the intermediate region of the central cylinder and remained so in the secondary tissue. Procambial strands ran along or within the thickening meristem at all levels of the stem. These observations lead us to believe that in Cordyline terminalis (i) the primary and secondary thickening meristems function as a single entity and (ii) the primary and secondary bundles describe a single, continuus vascular system.

scholarly journals Is the secondary thickening in palms always diffuse?

2013 ◽  
Vol 85 (4) ◽  
pp. 1461-1472 ◽  
Author(s):  
MARLI P. BOTaNICO ◽  
VERONICA ANGYALOSSY
Keyword(s):  
20Th Century ◽  
Secondary Growth ◽  
Central Cylinder ◽  
Early 20Th Century ◽  
Apical Region ◽  
Vascular Bundles ◽  
Cell Enlargement ◽  
The Past ◽  
Secondary Thickening ◽  
Meristematic Activity

Unlike other arboreal monocotyledons, the secondary growth of palms has for the past 100 years been described as diffuse. Solely cell enlargement and random parenchyma divisions, without the activity of a meristem, characterize such growth. Some previous works of the early 20th century have, however, mentioned the presence of a secondary meristem in the stems of palms, but this information was forgotten since then. Addressing to this question, we analysed palm stems of four species, with the aim to understand the possible presence of such secondary growth. We found that a meristematic band occurs between the cortex and the central cylinder and gives rise to new vascular bundles and parenchyma internally, producing parenchyma and fibres externally. It appears secondarily, i.e., it undergoes meristematic activity in the median and basal stem regions, far away from the apical region. In fact, a meristematic band is present and may be more common than currently believed, but uneasy to detect in certain palms for being restricted to specific regions of their stems. In conclusion, the diffuse secondary thickening is here shown not to be the only mechanism of secondary growth in palms. The presence of a meristem band in the stems of palms merits careful reconsideration.

Initiation and structure of the secondary vascular system in Phytolacca dioica (Phytolaccaceae)

1984 ◽  
Vol 62 (12) ◽  
pp. 2580-2586 ◽  
Author(s):  
Bruce K. Kirchoff ◽  
Abraham Fahn
Keyword(s):  
Vascular System ◽  
Secondary Growth ◽  
Tissue Response ◽  
Vascular Cambium ◽  
Vascular Cylinder ◽  
Primary Growth ◽  
Secondary Thickening ◽  
Dividing Cells ◽  
Cathodic Side ◽  
Vascular Connections

Phytolacca dioica (L.) is characterized by anomalous secondary thickening by means of supernumerary cambia. After a period of primary growth and the formation of an initial (normal) vascular cambium, supernumerary cambia are initiated outside of the primary vascular cylinder. The initiation of the first supernumerary cambium takes place through approximately the number of nodes equal to the denominator of the phyllotactic fraction characterizing a given axis. At each node a segment of supernumerary cambium is initiated opposite the leaf traces supplying the leaf inserted at that node. The segments of differentiated cambium are preceded by regions of obliquely and anticlinally dividing cells. In the single juvenile axis studied supernumerary cambial segments also appear above the node to the cathodic side of the entering leaf traces, and opposite the medullary bundle immediately anodic to these traces. Vascular connections among the primary and supernumerary vascular cylinders occur between leaf insertions on the same orthostichy. The levels at which these connections occur vary among stems. The switch from ordinary to anomalous secondary growth may be caused by a change in tissue response to stimuli produced by leaves.

Anatomy of Purple Nutsedge

Weed Science ◽  
1970 ◽  
Vol 18 (5) ◽  
pp. 631-635 ◽  
Author(s):  
G. D. Wills ◽  
George Ann Briscoe
Keyword(s):  
Leaf Surface ◽  
Vascular System ◽  
Single Layer ◽  
Growing Season ◽  
Lower Surface ◽  
Cyperus Rotundus ◽  
Vascular Bundles ◽  
Outer Cortex ◽  
Purple Nutsedge ◽  
Photosynthetic Cells

Purple nutsedge(Cyperus rotundus L.)develops as a series of shoots connected by bulbs, rhizomes, and tubers. The leaves contain parallel, collateral vascular bundles with the majority of the photosynthetic cells concentrated in the sheathing girdle around each bundle. The upper leaf surface consists of a single layer of large epidermal cells covered by a thick cuticle. Stomates occur only in the lower surface. The vascular bundles vary from collateral to amphivasal as they pass from the leaves through the bulb into the rhizomes and tubers. Newly developing rhizomes and tubers appear white and fleshy with a parenchymatous epidermis and cortex. Mature rhizomes appear brown and wiry with a deteriorated outer cortex and a lignified inner cortext and endodermis. Tubers and bulbs form similarly at the rhizome apices with each accumulating starch. The interconnecting vascular system appears to remain intact throughout the growing season.

scholarly journals General and peculiar features of vascular organization and development in shoots of Bougainvillaea glabra Choisy (Nyctaginaceae)

2015 ◽  
Vol 41 (1) ◽  
pp. 39-70 ◽  
Author(s):  
Z. Puławska
Keyword(s):  
Vascular System ◽  
Vascular Bundles ◽  
Lateral Extension ◽  
Fast Growing ◽  
Secondary Thickening ◽  
Lateral Shoots ◽  
Developmental Feature ◽  
Slow Growing

In the present study developmental relations between peripheral meristematic cylinder and vascular bundles of the young parts of the shoots and the relations between these bundles from the young elongating parts and those formed during secondary thickening has been elucidated. The suggestion is advanced that the limited lateral extension of bundles is an important developmental feature of the vascular system of <i>Bougainvillaea glabra</i> Choisy. The organization of the vascular system in thick fast growing sprouts and in the thin slow growing lateral shoots are described. It is shown that the quantitative differences in vascular organization, between both types of shoots are the manifestation of a close morphological harmonistation of the entire shoot, and particularly of its entire vascular system.

scholarly journals Morphoanatomy of the stem in Cyperaceae

2009 ◽  
Vol 23 (3) ◽  
pp. 889-901 ◽  
Author(s):  
Ana Claudia Rodrigues ◽  
Maria Emília Maranhão Estelita
Keyword(s):  
Apical Meristem ◽  
Vascular System ◽  
Secondary Growth ◽  
Cyperus Rotundus ◽  
External Morphology ◽  
Life Phase ◽  
Secondary Thickening ◽  
Primary Body ◽  
Stem Type ◽  
Phase Activity

Cyperaceae are usually perennial, with underground stems mainly rhizomatous, however, other stem types may also occur, such as corms and tubers. The underground stems of five Cyperaceae species were examined. Cyperus rotundus and Fuirena umbellata have plagiotropic rhizomes, while C. esculentus, C. odoratus, Hypolytrum schraderianum and Bulbostylis paradoxa have orthotropic rhizomes. Corms occur in C. rotundus and C. esculentus, and stolons in C. esculentus. The primary body originates from the activity of the apical meristem and later, from the primary thickening meristem (PTM). Secondary growth results from secondary thickening meristem (STM) activity, and occurs in rhizomes of H. schraderianum, B. paradoxa, C. odotarus and F. umbellata. The procambium and the PTM give rise to collateral bundles in H. schraderianum, and amphivasal bundles in the remaining species. The STM gives rise to the vascular system with the associated phloem and xylem. According to our results, the concept of stem type in Cyperaceae depends on external morphology, function, life phase, activity of the thickening meristems and the relative amount of parenchyma.

Anatomy of Yellow Nutsedge (Cyperus esculentus)

Weed Science ◽  
1980 ◽  
Vol 28 (4) ◽  
pp. 432-437 ◽  
Author(s):  
G. D. Wills ◽  
R. E. Hoagland ◽  
R. N. Paul
Keyword(s):  
Vascular System ◽  
Single Layer ◽  
Lower Surface ◽  
Vascular Bundles ◽  
Cyperus Esculentus ◽  
Outer Cortex ◽  
Yellow Nutsedge ◽  
Basal Bulb ◽  
Anatomical Arrangement ◽  
Pass Through

Yellow nutsedge (Cyperus esculentusL.) develops as a series of shoots, bulbs, and tubers connected by rhizomes. The leaves contain parallel, collateral vascular bundles with the majority of the chlorophyll-containing cells concentrated in two sheathing girdles around each bundle. The upper leaf surface consists of a single layer of large epidermal cells covered by a thick cuticle. Stomates occur primarily in the lower surface. The vascular bundles are collateral in the leaves and amphivasal in the rhizome, changing their anatomical arrangement as they pass through the basal bulb. Newly developing rhizomes and tubers are white and fleshy with a parenchymatous epidermis and cortex. Mature rhizomes are brown and wiry with a deteriorated outer cortex and a lignified inner cortex and endodermis. Tubers and bulbs form similarly at the rhizome apices with the tubers accumulating starch. The rhizome vascular system remains intact throughout the growing season.

Reassessing species boundaries in the Syagrus glaucescens complex (Arecaceae) using leaf anatomy

Botany ◽  
2021 ◽  
pp. 379-387
Author(s):  
D.H.T. Firmo ◽  
S.A. Santos ◽  
M.E.M.P. Perez ◽  
P. Soffiatti ◽  
B.F. Sant’Anna-Santos
Keyword(s):  
Species Identification ◽  
Leaf Anatomy ◽  
Vascular System ◽  
Identification Key ◽  
Species Boundaries ◽  
Vascular Bundles ◽  
Geographical Isolation ◽  
Species Occurrence ◽  
Species Diagnosis ◽  
High Degree

The Syagrus glaucescens complex comprises three species: Syagrus glaucescens Glaz. ex Becc., Syagrus duartei Glassman, and Syagrus evansiana Noblick. Recently, a new population of S. evansiana that possesses a high degree of endemism was reported in the Serra do Cabral mountain. Here we intend to study the leaf anatomy of the S. glaucescens complex and confirm whether this newly found population (from now on called Syagrus aff. evansiana) belongs to S. evansiana or not. Specimens were collected to investigate their leaf anatomy, which showed distinct differences between S. aff. evansiana and S. evansiana. The midrib anatomy revealed novelties for the S. glauscecens complex, proving useful for species diagnosis. Features such as accessory vascular bundles around the vascular system of the midrib and the number of collateral bundles are diagnostic for species identification. In addition, morphological and anatomical analyses indicated a correlation with the species occurrence. We found greater similarity between S. glaucescens and S. duartei, while S. evansiana and S. aff. evansiana are more alike. Here, we propose a new identification key based only on the leaf anatomy. Despite their morphological similarities, S. aff. evansiana and S. evansiana presented differences in leaf anatomy, which — when associated with their geographical isolation — suggests a fourth taxon in the complex.

scholarly journals Morphology and anatomy of leaf mine in Richterago riparia Roque (Asteraceae) in the campos rupestres of Serra do Cipó, Brazil

2002 ◽  
Vol 62 (1) ◽  
pp. 179-185 ◽  
Author(s):  
G. F. A. MELO DE PINNA ◽  
J. E. KRAUS ◽  
N. L. de MENEZES
Keyword(s):  
Host Plant ◽  
Vascular System ◽  
Glandular Trichomes ◽  
Protective Layer ◽  
Vascular Bundles ◽  
Campos Rupestres ◽  
Structural Alterations ◽  
Serra Do Cipó ◽  
Phenolic Substances

The leaf mine in Richterago riparia is caused by a lepidopteran larva (lepidopteronome). The leaves of R. riparia show campdodrome venation; the epidermis is unistratified, with stomata and glandular trichomes in adaxial and abaxial surfaces. The mesophyll is bilateral and the vascular system is collateral. During the formation of the mine, the larva consumes the chlorenchyma of the mesophyll and the smaller vascular bundles (veins of third and fourth orders). Structural alterations in the tissues of the host plant were not observed, except for the formation of a wound meristem and the presence of cells with phenolic substances next to the mine. Three cephalic exuviae of the miner were found in the mesophyll. This lepidopteronome is parenchymatic and the epidermis remains intact, but forms a protective layer for the mining insect.

scholarly journals Presence of Xylella fastidiosa in Sweet Orange Fruit and Seeds and Its Transmission to Seedlings

2003 ◽  
Vol 93 (8) ◽  
pp. 953-958 ◽  
Author(s):  
W.-B. Li ◽  
W. D. Pria ◽  
P. M. Lacava ◽  
X. Qin ◽  
J. S. Hartung
Keyword(s):  
Vascular System ◽  
Sweet Orange ◽  
Xylella Fastidiosa ◽  
Germination Rate ◽  
Citrus Fruit ◽  
Vascular Bundles ◽  
Specific Amplification ◽  
Root Grafts ◽  
Citrus Seeds

Xylella fastidiosa, a xylem-limited bacterium, causes several economically important diseases in North, Central, and South America. These diseases are transmitted by sharpshooter insects, contaminated budwood, and natural root-grafts. X. fastidiosa extensively colonizes the xylem vessels of susceptible plants. Citrus fruit have a well-developed vascular system, which is continuous with the vascular system of the plant. Citrus seeds develop very prominent vascular bundles, which are attached through ovular and seed bundles to the xylem system of the fruit. Sweet orange (Citrus sinensis) fruit of cvs. Pera, Natal, and Valencia with characteristic symptoms of citrus variegated chlorosis disease were collected for analysis. X. fastidiosa was detected by polymerase chain reaction (PCR) in all main fruit vascular bundles, as well as in the seed and in dissected seed parts. No visual abnormalities were observed in seeds infected with the bacterium. However, the embryos of the infected seeds weighed 25% less than those of healthy seeds, and their germination rate was lower than uninfected seeds. There were about 2,500 cells of X. fastidiosa per infected seed of sweet orange, as quantified using real-time PCR techniques. The identification of X. fastidiosa in the infected seeds was confirmed by cloning and sequencing the specific amplification product, obtained by standard PCR with specific primers. X. fastidiosa was also detected in and recovered from seedlings by isolation in vitro. Our results show that X. fastidiosa can infect and colonize fruit tissues including the seed. We also have shown that X. fastidiosa can be transmitted from seeds to seedlings of sweet orange. To our knowledge, this is the first report of the presence of X. fastidiosa in seeds and its transmission to seedlings.

Shade avoidance responses are mediated by the ATHB-2 HD-zip protein, a negative regulator of gene expression

Development ◽  
1999 ◽  
Vol 126 (19) ◽  
pp. 4235-4245 ◽  
Author(s):  
C. Steindler ◽  
A. Matteucci ◽  
G. Sessa ◽  
T. Weimar ◽  
M. Ohgishi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Proliferation ◽  
Cell Expansion ◽  
Lateral Root ◽  
Vascular System ◽  
Secondary Growth ◽  
Negative Regulator ◽  
Specific Cell ◽  
Shade Avoidance ◽  
Growth Responses

The ATHB-2 gene encoding an homeodomain-leucine zipper protein is rapidly and strongly induced by changes in the ratio of red to far-red light which naturally occur during the daytime under the canopy and induce in many plants the shade avoidance response. Here, we show that elevated ATHB-2 levels inhibit cotyledon expansion by restricting cell elongation in the cotyledon-length and -width direction. We also show that elevated ATHB-2 levels enhance longitudinal cell expansion in the hypocotyl. Interestingly, we found that ATHB-2-induced, as well as shade-induced, elongation of the hypocotyl is dependent on the auxin transport system. In the root and hypocotyl, elevated ATHB-2 levels also inhibit specific cell proliferation such as secondary growth of the vascular system and lateral root formation. Consistent with the key role of auxin in these processes, we found that auxin is able to rescue the ATHB-2 lateral root phenotype. We also show that reduced levels of ATHB-2 result in reciprocal phenotypes. Moreover, we demonstrate that ATHB-2 functions as a negative regulator of gene expression in a transient assay. Remarkably, the expression in transgenic plants of a derivative of ATHB-2 with the same DNA binding specificity but opposite regulatory properties results in a shift in the orientation of hypocotyl cell expansion toward radial expansion, and in an increase in hypocotyl secondary cell proliferation. A model of ATHB-2 function in the regulation of shade-induced growth responses is proposed.

Sign in / Sign up

Export Citation Format

Share Document