CHAPTER X ARRANGEMENT OF VASCULAR BUNDLES (Part 1)

CHAPTER X ARRANGEMENT OF VASCULAR BUNDLES Having familiarized ourselves with the different types of mechanical and conducting cells, we shall now consider the different ways in which these cells are associated to form the vascular and fibro-vasctslar bimdles. The simplest form of the vascular bundle occurs in petals, floral bracts, and leaves. In these parts the vascular bundle is made up of conducting cells only. In the great majority of cases, however, the conducting cells are associated with mechanical cells to form the fibro-vascular bundle. The fibro-vascular bundle is made up of, first, the phloem, which consists of sieve tubes, companion cells, bast fibres, and parench)rma; secondly, of the zylem, composed of vessels and tracheids, wood fibres and wood parenchyma; thirdly, of medul- lary rays (restricted to certain tjpes); and fourthly, of the bundle sheath (restricted to certain types). TYPES OF FIBRO-VASCULAR BUNDLES There are three well-defined types of the fibro-vascular bundle, namely, the radial, the concentric, and the collateral types. RADIAL VASCULAR BUNDLES The radial type of bundle is met with most frequently in monocotyledonous roots. In this form (Plate 114) the xylem forms radial bands of tissue which alternate with isolated groups of phloem. The space between the phloem and xylem is filled in with either parenchyma or fibres, or both. In some cases the vessels of the xylem meet in the centre of the root, while in other cases 292 Cxos»-SECTtON OF A Radial Vasculab BUNDLE OF Skcne Cabbagb Root (Symplocarpui Jtrtidus [L.|, Nutt.) 2. Bundle sheath. 3. Parenchyma. 4. Seve cells. Cross-Section ok a Phloem -Centric Bundle of Calamus Rhizome {Acorus caiamus, L.) 2. Sieve cells. 3. Phloem parenchyma. 4. Parenchyma surrounding the bundln. ARRANGEBfENT OF VASCULAR BUNDLES 295 the centre of the stem is occupied by pith parench)ana. Each bundle is surrounded by parench)rma cells, and in iris, calamus, and veratrum, rhizomes, and endodermis, surrounds the bundles located in the centre of the stem, consisting of thin-walled (mechanical) cells. In sarsaparilla root, the pith is composed of thick-walled, porous pith parench)rma cells with starch. Outside the pith are arranged radial bands of oval vessels which decrease in size toward the periphery. Between the ends of these bands occur isolated groups of sieve cells. Surroimding the sieve cells and vessels are thick-walled, angled fibres. External to these cells is an endodermis composed of lignified brownish-colored cells one layer in thickness. CONCENTRIC VASCULAR BUNDLES There are two principal types of the concentric bundle, namely, xylem-centric, in which the xylem is centric and the phloem is peripheral, as in Veratrum root; and phloem-centric (Plate 125), in which the phloem is centric and the xylem pe- ripheral, as in calamus rhizome. COLLATERAL VASCULAR BUNDLES There are three types of collateral vascular bundles — namely, closed collateral, bi-collateral, and open collateral. In the closed collateral bundle the phloem and xylem are not separated by a cambium layer, and in many cases the bundle is surrounded by thick, angled walled fibres, as in palm stem. The term closed bundle refers to the fact that there is no cambium between the xylem and phloem, therefore the bimdle is "closed*' to further growth, and not to the fact that it is frequently surrounded by fibres which prevent further growth. In podophyllum stem (Plate 126) the xylem portion of the bundle faces the centre of the stem and the phloem portion of the bundle faces the epidermis. The xylem and phloem are separated by a cambium layer, and both are surrounded by thick-walled angled fibres which are the chief mechanical cells of the stem. This bundle is, in fact, mechanically closed, but not physiologically because a cambium is present. Cross-Section of a Closed Collaterai. Bundle i {Podophyllum pettatum, L.) 3. Sieve cells, 3. Cambium. 5. Parenchyma. 6. Intercellular space. ' Mandbake Sisk Bl-COLLATSKAL. BUNDLE OF PuUPKIN SteU (.CurCHrbUa pepo, L.) 2. ^eve tubes. 298 HISTOLOGY OF MEDICINAL PLANTS BI-COLLATERAL VASCULAR BUNDLES In the bi-coUateral vascular bundle (Plate 127) the xylem is in between two groups of phloem — namely, an inner group and an outer group. In pumpkin stem a bimdle occurs in each angle of the stem. The entire bundle is surrounded by parenchyma cells. In an individual bundle the xylem consists of large circular vessels and a phloem containing large sieve cells, many of which show the yellow porous sieve plates. OPEN COLLATERAL VASCULAR BUNDLES In the open collateral bimdle (Plate 100) the xylem and phloem are separated by the cambium layer, which, through its divisions, causes the stem to increase in thickness each year. This type of bundle is characteristic of the stems and roots of dicotyledonous plants. The bi-coUateral bimdle occurs in many leaves. The xylem in such cases is central, the phloem strands occupying upper and lower peripheral positions. INDEX Abb^ condenser, illustration, 1 1 Absorption tissue, introduction, 121 tissue of leaves, 125 Aerating tissue, introduction, 151 Annular vessels, illustration of, 129 Bark, of white pine powdered, de- scription of, 250 of white pine powdered, illustra- tion of, 251 unrossed white pine, cross-sec- tion, illustration of, 249 Barks, description of, 248 diagnostic structures of, 253 structural variations of, 252 Base sledge microtome, 35 sledge microtome, illustration, 35 Bast fibres, 89 branched, 92 branched, illustrations, 95 crystal bearing, 90, 92 description of, 100 grroups of, illustrations, 102 non-porous and non-striated, 96 non-porous and non-striated, il- lustrations, 1 01 non-porous and striated, 96 occurrence in powdered drugs, 103 of barks, illustrations, 91, 93, 94 of klip buchu leaf, 262 of ruellia rhizome, 226 of ruellia root, 223 of ruellia stem, 235 of spigclia stem, 235 porous and non-striated, illus- trations, 98 porous and dtriated, 92 porous and striated, illustrations, 97 storage function of, 179 striated and non-porous, illus- trations of, 99 Bi-coUateral vascular bundles, de- scription of, 298 Buchu stems, cross-section, illustra- tion of, 243 cross-section, illustration of, 244 pow^dered, description of, 245 powdered, illustration of, 246 Cambium of pink root, 221 of ruellia rhizome, 226 of ruellia stem, 237 of spigelia rhizome, 223 of spigelia stem, 235 Camera lucida, 22 illustrations, 22 Care of microscope, 28 Celery fruit, diagrammatic drawing of, 287 Cell contents, 182 aleurone grains, 197 aleurone grains, description of, 198 aleurone grains, form of, 197 aleurone grains, structure of, 197 aleurone grains, tests for, 198 chlorophyll, 182 crystals, 200 crystals, composition of, 200 crystals, micro-, 200 crystals, raphides, 200 crystals, rosette, 200 crystals, solitary, variation of, 205 cystoliths, 210 cystoliths, forms of, 210 cystoliths, occurrence of, 215 cystoliths, tests for, 215 hesperidin, 196 hesperdiin, test for, 196 inulin, 194 inulin, tests for, 194 leucoplastids, 183 mucilage, 194 299 300 INDEX Cell contents, mucilage associated with raphides, tests for, 194 mucilage, tests for, 194 organic, 182 starch grains, formation of, 183 starch grains, hilum nature of, 188 starch grains, hilum of, 185 starch grains, mounting of, 188 starch grains, occurrence of, 184 starch grains, outline of, 185 starch grains, size of, 185 starch grains, tests for, 188 tannin, 196 tannin, occurrence of, 196 tannin, test for, 197 volatile oil, test for, 196 volatile oils, 196 Cell di'ision common to onion root, 56 Cell plate, 55 Cell sap, 53 Cell, typical, 53 Cell wall, 53 Chromatin, 54 Chromatin granules, 55 Chromatophores, 53 Chromosomes, 55 Closed collateral bundles of mandrake stem, cross-section illustration of, 296 Collateral vascular bundles, 295 Collenchyma cells, composition of walls, 109 illustrations, 108 occurring in catnip and mother- wort, illustrations, 107 of rucllia stem, 235 structure of, 106 Compound microscope, illustration, 10 microscope, mechanical parts of, 7,8 microscope of Robert Hooke, illustration, 8 microscope, optical parts of, 9, II, 12 microscopes, introduction, 7 Concentric vascular bundles, 295 Conducting tissue, introduction, 126 Cork cells, origin of, 88 Cortical parenchyma, conduction by, 147 of ruellia stem, 235 Cortex, of pink root, 219 of ruellia rhizome, 226 of ruellia root, 221 of ruellia stem, 235 of spigelia rhizome, 223 of spigelia stem, 233 Cover glasses, 43 illustrations, 44 Crystal cavities, 176 cells, storage function of, 179 Cutting sections, 31 Cystoliths, illustrations of, 214 Cytoplasm, 53 Daisies, white, powdered, description of, 282 illustration of, 283 Dissecting microscope, illustration, 5 needles, 46 needles, illustration, 46 Drawing apparatus, illustration, 23 Ectoplast, 53 Embryo, diagnostic structures of, 291 Endocarp of celery fruit, 288 Endodermal cells, illustrations of longitudinal sections, 11 9 illustrations of cross-sections, 117 introduction, 116 structure of, 116, 118 Endodermis, of klip buchu leaf, 262 of pink root, 219 of ruellia root, 223 Endosperm of celery fruit, 288 of seeds, 291 Epicarp of celery fruit, 285 Epidermal cells of leaves, storage function of, 179 Epidermis, surface deposits of, 62 of herbaceous stems, illustra- tions of, 152 of klip buchu leaf, 260 of leaves, illustrations of, 155 of mountain laurel, 264 of pink root, 219 of ruellia rhizome, 226 of ruellia root, 221 of ruellia stem, 235 of seeds, 289 of spigelia rhizome, 223 of spigelia stem, 233 of testa, 63 INDEX 301 Epidermis of trailing arbutus, 264 Equatorial plane, 55 plate, 55 Fibro-vascular bundles, composition of, 292 of klip buchu leaf, 262 types of, 292 Flowers, diagnostic structures of, 284 parts of, 270 Folding magnifier, 4 illustration, 4 Fruits, cellular structure of, 285 diagnostic characteristics of, 288 diagnostic structures of, 288 Glandular hairs of peppermint, 178 illustrations of, 165 multicellular, 164 multicellular, multiscriate stalked, 166 multicellular, multiseriate stalked, description of, 166 multicellular, multiseriate stalked, occurrence, 166 multicellular sessile, 164 multicellular stalked, 164 multicellular, uniscriate stalked, 164 stalked, illustrations of, 167 storage function of, 178 unicellular, 164 unicellular, multiseriate stalked, 164 unicellular sessile, 164 unicellular stalked, 164 unicellular, uniseriate stalked, 164 Glandular tissue, introduction, 164 Glass slides, 44 illustrations, 44 Greenough binocular microscope, 15 illustration, 15 Guard cells, 151 Hairs, multicellular, multicellular non-branched, illustration, 75 multicellular, multiscriate branched, of Shepherdia, 78 multicellular, multiscriate branched, 77, 82 multicellular, multiseriate branched, illustrations, 79, 81 Hairs, multicellular, multiseriate non- branched, 74 multicellular, uniseriate branched, illustration, 76 multicellular, uniseriate n o n - branched, 72 multicellular, uniseriate n o n - branched, illustrations of, 73 Hand cylinder microtome, illustra- tion, 34 microtome, 31 microtome, illustration, 31 table microtome, 34 table microtome, illustration, 34 Horehound, powdered, description of, 237 powdered, illustration of, 238 spurious, powdered, description of, 237 spurious, powdered, illustration of, 239 Hypoderm of seeds, 289 Hypodcrmal cells, of leaves, storage function of, 179 illustrations, 120 structure of, 118 Hypoderms, of klip buchu leaf, 260 of ruellia root, 221 Illumination for microscope, 26 Indirect cell division, 54, 55 Inner bark of white pine, 248 epidermis of seeds, 291 Insect flower leaves, powdered, illus- trations of, 268 stems, description of, 241 stems, powdered, illustration of, 240 Insect flowers, closed, powdered, illus- tration of, 279 open, description of, 280 open, powdered, illustration of, 281 powdered, description of, 278 Intercellular spaces, 158 illustrations of, 160, 161 Internal phloem, of spigelia stem, 235 Inulin, illustrations of, 195 Karyokinesis, 54, 55 Klip buchu, cross-section, illustration of, 261 powdered, description of, 262 [>owdered, illustration of, 263 302 INDEX Labeling, 47 Latex cavities, 176 tube cavities, 176 tubes, 142, 144 tubes, illustration of, 145 vessels, illustrations of, 146 Leaf epidermis, 59 illustrations, 60, 61 Leaf parenchyma, conduction by, 150 Leaves, diagnostic structures of, 267 stomata, 260 Lenticel, illustration of cross-section, 159 Lenticels, aerating function of, 157 structure of, 158 Linin, 54 Long paraffin process, 29 Machine microtomes, 32 Measuring cylinder, 40 illustration, 40 Mechanical stage, 21 stage, illustration, 22 tissue, 89 Medullary ray, 139 bundle, 139 bundle in tangential-section of quassia wood, 258 cell, 141 cell, arrangement of, in the ray, 142 cell, structure of, 142 cells, in cross-section of quassia wood, 254 cells, in radial-section of quassia wood, 258 cells, in tangential-section of quassia wood, 258 cells, of ruellia stem, 237 Medullary rays, illustration of cross- sections of, 143 illustration of longitudinal sec- tion, 140 in cross-section of quassia wood, 254, in radial-section of quassia wood, 254 of pink root, 221 of ruellia rhizome, 227 of ruellia root, 223 of spigelia rhizome, 226 of white pine bark, 250 Mesocarp of celery fruit, 285 Method of mounting specimens, 41 Micro-crystals, illustrations of, 201 lamp, 27 Micrometer eye-pieces, 21 illustrations, 20, 21 Microphotographic apparatus, 24 illustration, 24 Microscope, how to use, 25 Microscopic measurements, 19 Microtome, care of, 36 Middle bark of white pine, 248 lamella, 55 layers of seeds, 291 Minor rotary microtome, 36 illustration, 36 Mountain laurel, cross-section, illus- tration of, 265 Mucilage cavities, 172, 176 Multicellular hair, 72 Nuclear membrane, 55 spindle, 55 Nucleoli, 55 Nucleus, 53 Objectives, illustrations, 11 Ocular micrometer, 19 illustration, 19 Oil cavities, occurrence, 178 of leaves, 178 of seeds, 178 unicellular, 172 Open collateral vascular bundles, de- scription of, 298 Origin of multicellular plants, 57 Outer bark of white pine, 248 Palisade parenchyma, conduction by, 150 Papillae, 67 illustrations of, 275 of stigmas, illustrations of, 276, 277 stigma, description of, 274 Paraffin, blocks, 31 embedding oven, illustration, 30 Parenchyma, aquatic plant, 150 cells of white pine, 248 conduction by, 144 cortical, illustrations of, 148 of mountain laurel, 264 of trailing arbutus, 264 pith, illustrations of, 149 Pericycle of pink root, 221 of ruellia root, 223 INDEX 303 Periderm, 8o cork, 80 illustrations of, 86 of cascara sagrada, illustrations, of white oak bark, illustration of, 87 parenchyma and stone cells, 85 stone cells, 85 Permanent mounts, 41 Pharmacognostic microscope, illus- tration, 12 Phloem, centric bundle of calamus, cross-section, illustration of, 294 of ruellia rhizome, 226 of ruellia stem, 235 of spigelia rhizome, 223 of spigelia stem, 233 Phloem parenchyma, conduction by, 150 of pink root, 221 of ruellia rhizome, 226 of ruellia root, 223 of ruellia stem, 235 of spigelia rhizome, 223 of spigelia stem, 235 Photosynthetic tissue, 163 Pink root, description of, 227 Pith parenchyma, conduction by, 147 of pink root, 221 of ruellia rhizome, 227 of ruellia root, 223 of ruellia stem, 237 of spigelia rhizome, 226 of spigelia stem, 235 Pitted vessels, with bordered pores, illustration of, 135 illustrations of, 134 Plant hairs, forms of, 67 introduction, 66 Polar caps, 55 Polarization microscope, 16 illustration, 16 Pollen grains, 270 non-spiny-walled, description of, 273 smooth- walled, illustrations of, 271 spiny-walled, description of, 273 spiny-walled, illustrations of, 272 Preparation of specimens for cutting, 28 Protoplast, 53 Quassia wood, cross-section, illustra- tion of, 255 radial-section, illustration of, 257 Radial vascular bundles, 292 skunk cabbage root, cross-sec- tion, illustration of, 293 Raphides, illustrations of, 203 Reading glass, 4 illustration, 4 Reagent set, illustration, 39 Reagents, list of, 38 Research microscope, 13 illustration, 14 Reserve cellulose, illustrations of, 180-181 Reticulate vessels, illustrations of, 133 Root hairs, 121, 122, 125 illustration of, 123 illustration of fragments, 124 Roots and rhizomes, 219 diagnostic structures of, 227 Rosette and solitary crystals, illus- trations of, 213 crystals, illustrations of, 204 crystals, inclosed, illustrations of, 206 Ruellia ciliosa, Pursh., powdered, illustration of, 229 ciliosa, Pursh., rhizome, cross- section, illustration of, 225 ciliosa, Pursh., stem, cross-sec- tion, illustration of, 236 root, description of, 227 root, illustration of, 222 Scalpels, 46 illustration, 47 Scissors, 46 illustration, 46 Sclariform vessels, illustrations of, 132 Seeds, parts of, 289 Secretion cavities, of celery fruit, 288 description of, 176 illustrations of, 169-171 introduction, 166 lysigenous, 168 schizogenous, 168 schizo-lysigenous, 168 unicellular, 168 304 INDEX Secretion cells, of klip buchu leaf, 262 of white pine, 248 Short paraffin process, 29 Sieve cells, of klip buchu leaf, 262 of pink root, 221 of ruellia rhizome, 226 of ruellia root, 223 of ruellia stem, 235 of spigelia stem, 235 Sieve plate, 138 illustration of, 137 Sieve tube, illustration of, 137 tubes, introduction, 136 tubes, structure, 136 Simple microscope, introduction, 3 Slide box, 48 box, illustration, 48 cabinet, 49 cabinet, illustration of, 49 forceps, 45 forceps, illustrations, 45 . tray, 48 tray, illustration, 48 Solitary crystals, illustrations of, 207- 209, 211, 212 unicellular hairs, 69 Special research microscope, 14 illustration, 14 Specimens, preservation of, 48 Spermoderm, of celery fruit, 288 of seeds, 289 Spigelia marylandica, powdered, il- lustration of, 228 rhizome, cross-section, illustra- tion of, 224 root, cross-section, illustration of, 220 stem, cross-section, illustration of, 234 Spindle fibres, 55 Spiral vessels, illustrations of, 129, 130 Spongy parenchyma of klip buchu, 260 Stage micrometer, 19 illustration, 19 Staining dish, 40 illustration, 40 Standardization of ocular microm- eter, 19 Starch grains, illustrations of, 186, 187, 189-193 Steinheil lens, 5 illustration, 5 Stems, diagnostic structures of, 233 dicotyledonous, 233 herbaceous, 233 monocotyledonous, 233 Stomata, aerating function of, 151 illustrations of cross-section, 156 relation to surrounding cells, 154 types of, 153 Stone cells, of ruellia root, 223 branched, 109 branched, illustrations of , no description, in, 112 introduction, 109 occurrence, illustrations, 115 porous and non-striated, 1 1 1 porous and non-striated, illus- trations of, 114 porous and striated, 109 porous and striated, illustrations of, 113 storage function of, 178 Storage cavities, 176 cavities, illustrations of, 177 cells, 173 cells, cortical parenchyma, 173 cells, illustrations of, 1 74 cells, pith parenchyma, 173 cells, wood parenchyma, 173 tissue, 173 walls, description of, 179 Stored mucilage and resin, illustra- tions of, 175 Surrounding cells, arrangement of, 154 Synthetic tissue, introduction, 163 Temporary mounts, 41 Testa cells, 65 epidermal cells, illustrations, 64 Tracheids of pink root, 221 Trailing arbutus leaf, cross-section, illustration of, 266 Tripod magnifier, 4 illustration, 4 Turntable, 46 illustration, 47 Under epidermis of klip buchu leaf, 262 epidermis of mountain laurel, 264 INDEX 305 Under epidermis of trailing arbutus, 264 hypodermis of klip buchu leaf, 262 palisade parenchyma of klip buchu leaf, 262 Unicellular clustered hairs, 72 clustered hairs, illustrations, 71 non-glandular hairs, 69 solitary branched hairs, 72 solitary hairs, illustrations, 70 Upper palisade parenchyma of klip buchu leaf, 260 palisade parenchyma of moun- tain laurel, 264 Vacuoles, 53 Vascular bundles, arrangement of, 292 occurrence of, 292 Vessels, annular, 127 and tracheids, introduction, 126 in cross-section of quassia wood, . 254 . in radial-section of quassia wood, 254 . in tangential-section of quassia wood, 258 of ruellia rhizome, 226 of ruellia ro