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-vascular bundles=.
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 parenchyma; secondly, of the =xylem=, composed of vessels and tracheids, wood fibres and wood parenchyma; thirdly, of medullary rays (restricted to certain types); 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 the centre of the stem is occupied by pith parenchyma. Each bundle is surrounded by parenchyma 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.
[Illustration: PLATE 124
CROSS-SECTION OF A RADIAL VASCULAR BUNDLE OF SKUNK CABBAGE ROOT (_Symplocarpus fœtidus_ [L.], Nutt.)
1. Vessels. 2. Bundle sheath. 3. Parenchyma. 4. Sieve cells.]
[Illustration: PLATE 125
CROSS-SECTION OF A PHLOEM-CENTRIC BUNDLE OF CALAMUS RHIZOME (_Acorus calamus_, L.)
1. Vessels. 2. Sieve cells. 3. Phloem parenchyma. 4. Parenchyma surrounding the bundles.]
In sarsaparilla root, the pith is composed of thick-walled, porous pith parenchyma 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.
Surrounding 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 peripheral, 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 bundle 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.
[Illustration: PLATE 126
CROSS-SECTION OF A CLOSED COLLATERAL BUNDLE OF MANDRAKE STEM (_Podophyllum peltatum_, L.)
1. Vessels. 2. Sieve cells. 3. Cambium. 4. Fibres. 5. Parenchyma. 6. Intercellular space.]
[Illustration: PLATE 127
BI-COLLATERAL BUNDLE OF PUMPKIN STEM (_Curcurbita pepo_, L.)
1. Vessels. 2. Sieve tubes.]
BI-COLLATERAL VASCULAR BUNDLES
In the bi-collateral 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 bundle 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 bundle (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-collateral bundle occurs in many leaves. The xylem in such cases is central, the phloem strands occupying upper and lower peripheral positions.
INDEX
Abbé condenser, illustration, 11
Absorption tissue, introduction, 121 tissue of leaves, 125
Aerating tissue, introduction, 151
Annular vessels, illustration of, 129
Bark, of white pine powdered, description of, 250 of white pine powdered, illustration of, 251 unrossed white pine, cross-section, 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 groups of, illustrations, 102 non-porous and non-striated, 96 non-porous and non-striated, illustrations, 101 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 spigelia stem, 235 porous and non-striated, illustrations, 98 porous and striated, 92 porous and striated, illustrations, 97 storage function of, 179 striated and non-porous, illustrations of, 99
Bi-collateral vascular bundles, description of, 298
Buchu stems, cross-section, illustration of, 243 cross-section, illustration of, 244 powdered, 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 hesperidin, test for, 196 inulin, 194 inulin, tests for, 194 leucoplastids, 183 mucilage, 194 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 division 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 motherwort, illustrations, 107 of ruellia 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, 11, 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, 119 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, illustrations 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
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, multiseriate stalked, 166 multicellular, multiseriate stalked, description of, 166 multicellular, multiseriate stalked, occurrence, 166 multicellular sessile, 164 multicellular stalked, 164 multicellular, uniseriate 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, multiseriate branched, of Shepherdia, 78 multicellular, multiseriate branched, 77, 82 multicellular, multiseriate branched, illustrations, 79, 81 multicellular, multiseriate non-branched, 74 multicellular, uniseriate branched, illustration, 76 multicellular, uniseriate non-branched, 72 multicellular, uniseriate non-branched, illustrations of, 73
Hand cylinder microtome, illustration, 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
Hypodermal 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, illustrations of, 268 stems, description of, 241 stems, powdered, illustration of, 240
Insect flowers, closed, powdered, illustration 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 powdered, illustration of, 263
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, ærating 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 section, 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, illustration 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, description of, 298
Origin of multicellular plants, 57
Outer bark of white pine, 248
Palisade parenchyma, conduction by, 150
Papillæ, 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
Periderm, 80 cork, 80 illustrations of, 86 of cascara sagrada, illustrations, 84 of white oak bark, illustration of, 87 parenchyma and stone cells, 85 stone cells, 85
Permanent mounts, 41
Pharmacognostic microscope, illustration, 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, illustration of, 255 radial-section, illustration of, 257
Radial vascular bundles, 292 skunk cabbage root, cross-section, 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, illustrations 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-section, 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
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, illustration of, 228 rhizome, cross-section, illustration 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 micrometer, 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, ærating 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, 110 description, in, 112 introduction, 109 occurrence, illustrations, 115 porous and non-striated, 111 porous and non-striated, illustrations 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, 174 cells, pith parenchyma, 173 cells, wood parenchyma, 173 tissue, 173 walls, description of, 179
Stored mucilage and resin, illustrations 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 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 mountain 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 root, 223 of ruellia stem, 237 of spigelia rhizome, 226 pitted, 131 pitted with bordered pores, 131 reticulate, 131 sclariform, 128 spiral, 127
Water pores, aerating function of, 151
Watchmaker’s loupe, 4 illustration, 4
Wood fibres, color of, 104 illustrations, 105 in cross-section of quassia wood, 254 in radial-section of quassia wood, 258 in tangential-section of quassia wood, 258 introduction, 104 structure of, 104
Wood parenchyma, conduction by, 150 in cross-section of quassia wood, 254 in radial-section of quassia wood, 258 of pink root, 221 of ruellia rhizome, 227 of ruellia root, 223 of ruellia stem, 237 of spigelia rhizome, 226 of spigelia stem, 235
Woods, description of, 254 diagnostic structures of, 258
Woody stems, buchu stem, description of, 242 mature buchu stem, 242
Xylem, of pink root, 221 of ruellia rhizome, 226 of ruellia root, 223 of ruellia stem, 237 of spigelia rhizome, 226 of spigelia stem, 235
Transcriber’s Notes
The Table of Illustrations at the beginning of the book was created by the transcriber.
Inconsistencies in hyphenation such as “extra-ordinary”/“extraordinary” have been maintained.
Minor punctuation and spelling errors have been silently corrected and, except for those changes noted below, all misspellings in the text, especially in dialogue, and inconsistent or archaic usage, have been retained.
Page 53: “The outer portion of the nucelus” changed to “The outer portion of the nucleus”.
Page 54: “the centre of the nucelus” changed to “the centre of the nucleus”.
Page 62: “typical forms of arrangement of epidermal calls” changed to “typical forms of arrangement of epidermal cells”.
Page 104: “of logwood and santalum rubum” changed to “of logwood and santalum rubrum”.
Page 107: “the cross-section of catnip stem (_Nepeta cateria_” changed to “the cross-section of catnip stem (_Nepeta cataria_”.
Page 120: “Cross-section sarsaparilla root (_Smilex officinalis_” changed to “Cross-section sarsaparilla root (_Smilax officinalis_”.
Page 150: “cells are the narrowest parenchyma cells occuring” changed to “cells are the narrowest parenchyma cells occurring”.
Page 155: “Upper epidermis of deer tongue (_Trilisia odoratissima_” changed to “Upper epidermis of deer tongue (_Trilisa odoratissima_”.
Page 171: “Parenchyma cells with protuding” changed to “Parenchyma cells with protruding”.
Page 193: “grains of paradise (_Amomum meleguetta_” changed to “grains of paradise (_Amomum melegueta_”.
Page 237: “Marrubium perigrinum, which is a related species of horehound” changed to “Marrubium peregrinum, which is a related species of horehound”.