Sclerenchyma

Sklerenchym, n. (Biol.) sclerenchyma. sklerosieren, v.i. become indurated, harden. Skleroskophkrte, /. scleroscope hardness. Skonto, m. discoimt,... 

Wood fiber (type of sclerenchyma cell) Larger, more slender than the tracheid tapering heavy wall thickening and lignification pits are reduced in size and number relative to tracheids Protoplast lost as cell attains maturity Strength... 

Sclerenchyma Conductive tissue Sclerenchyma cells Mechanical support... 

Scintillation detector, 26 420, 433-434 SCISS P-Scission reactions, 24 280-281 SCK micelles, 20 489, 490 Sclareol, 24 573 Sclareolide, 24 573 Sclerenchyma cells, 22 18 Scleroglucan, 20 578, 4 724t... 

Wardrop (13,14) examined sclerenchyma fibers of Liriodendron tulip-ifera and sclereids of Pyrus communis, previously fixed with KMn04, and concluded that the vesicles supplied their contents to the cell wall, though the origin of the vesicles was not established. As discussed before, however, permanganate fixation is undesirable for these cytological observations. 

Oxidation of Salts from Ferulic and / -Fluoroferulic Acids. When stem sections were incubated with ferulic acid, isopropylamine or sodium salts, the cell walls of the youngest xylem or sclerenchyma elements were stained a light pink color. No reaction was observed in other cell walls (Table I). The same result was obtained with fluorinated analogues. The fact that only peroxidases from lignifying cell walls are able to oxidize ferulic compounds and syringaldazine must be emphasized. Absorption spectra of the pink oxidation products of ferulic acid and / -fluoroferulic acid in the presence of hydrogen peroxide and peroxidases extracted from tobacco cell walls ( covalently bound fraction) showed a peak at 520 nm. 

The collenchyma, present in herbs, is composed of elongated supporting cells and the sclerenchyma of woody plants is made up of supporting cells with hard lignified cell walls and a low water content. 

Typical mature roots have different shapes (conical, conical-cylindrical, cylindrical, fusiform) and different sizes (3 to 15 centimeters in diameter), depending on variety, age and growth conditions. The color of the outer peel varies from white to dark brown. The cross-section of cassava roots shows the two major components which are the peel and the central pith (Figure 12.1). The peel is composed of the outer layer (called the periderm) and the inner layer (called the cortical region or cortex), which contains sclerenchyma, cortical parenchyma and phloem tissue. The large central pith of the roots is the starch-reserve flesh, comprised of cambium and parenchyma tissue and xylem vessels. 

Fig. 4.2.3. A UV photomicrogrpah of thickened secondary wall of Larix leptolepis sclerenchyma cell. (Imagawa 1981)...

Over the millennia, food plants and animals have been selected and bred to reduce their intrinsic toughness animals have developed strategies for coping with foods that are difficult to harvest and chew. For instance, the parallel sclerenchyma... 

Plants are predominantly composed of parenchyma and woody tissues. Parenchyma cells dominate the green tissues in leaves and are composed of a protein-rich protoplast surrounded by a cellulose wall. Woody plant cells dominate all support (sclerenchyma) and transport (xylem and phloem) stmctures in a plant. They are composed of several layers (middle lamella, primary wall, secondary wall, and tertiary wall) with varying proportions of cellulose, hemicellulose, and lignin (Fengel and Wegener, 1984). 

Crystal fibers are longitudinal rows of superimposed parenchyma cells each of which contains a single monoclinic prism or rosette aggregate. Crystal fibers are found adjacent to sclerenchyma fibers such as bast or woody fibers. 

When sclerenchyma is composed of cells which are greatly elon-... 

Fig. 43,—Sclerenchyma fibers from different sources, i, Prom powdered cinnamon bark 2, End of bast fiber of flax stem showing transverse markings (6) 3, middle portion of flax fiber showing characteristic cross markings at b 4, bast fiber from cinchona bark 5, branched bast fiber from choke cherry bark 6. above, end, and below, median portion of bast fiber of jute. All highly magnified.

Bast fibers Wood fibers Sclerenchyma fibers Stone cells Collenchyma... 

Fig. 68.—Photomicrograph of cross-section of stem of Aristolochia sipko, where cambial activity is just beginning, a, Epidermis b, coUenchyma c, thin-walled parenchyma of the cortex, the innermost cell layer of which is the starch sheath or endodermis d, sclerenchyma ring of the pericycle e, thin-walled parenchyma of the pericycle /, primary medullary ray g, phloem h, xylem interfascicular cambium medulla or pith. X 20. (From Stevens.)...

Pig. 8o.—Photomicrograph of a representative portion of Greenbrier stem showing epidermis (,e.p.), cortex (c), endodermis (e.n.d.), cylinder sheath (c.s.), sclerenchyma fibers of closed collateral bundle ( ), fundamental parenchyma (J.p.), trachea (/). X 22. 

V. Drupaceous Fruits (Succulent fruits in which the mesocarp is more or less succulent, but the endocarp leathery or stony).— A Drupe is a one-celled, one-seeded drupaceous fruit such as the fruit of the Plum, Peach, Prune, Sabal, Rhus, Piper, Cherry, etc., whose endocarp or putamen is composed wholly of stone cells or stone cells and sclerenchyma fibers. Fig. 103 (i). 

Ten pages have been added to Chapter V on Cytology. Under Protoplasm and its Properties, six pages have been written on the subject of Irritability and Irritable Reactions. Under Non-Pro toplasmic Cell Contents several additional commercial starches are discussed and two original plates on starch grains added. Additional cuts on Collenchyma, Stone Cells, Sclerenchyma Fibers, Trichomes and Fibrovascular Bundles have been inserted in Chapter VI. 

The most metabolic activity of plants is carried out in the tissue called parenchyma, which generally makes up the bulk of the volume of all soft edible plant structures. The epidermis, which sometimes is replaced by a layer of corky tissue, is structurally modified to protect the surface of the organ. The highly specialized tissues collenchyma and sclerenchyma provide mechanical support for the plant. Water, minerals, and products of metabolism are transported from one part to another of the plant through the vascular tissues, xylem and phloem, which are the most characteristic anatomical features of plants on the cross section. 

Ferulate 5-hydroxylase (F5H) catalyzes the third P-450 hydroxylation step at the C5 position of the phenolic ring to ultimately afford, via the monolignol pathway, 5-hydroxyconiferyl (22) and/or sinapyl (23) alcohols. This P-450 was first detected in xylem and sclerenchyma-enriched tissues from poplar Populus x euramericana), with microsomal extracts able to catalyze hydroxylation of ferulic acid (6) to 5-hydroxyferulic acid (7) in the presence of NADPH with apparent values of 6.3 pmoll / This enzyme was thus characterized as F5H. 

---