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.

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.]

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.

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.]

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”.