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Elias Landolt; Irmgard Jäger-Zürn; R. A. Schnell:

Extreme Adaptations in Angiospermous Hydrophytes

1998. XII, 290 pages, 226 figures, 7 tables, 17x24cm, 850 g
Language: English

(Encyclopedia of Plant Anatomy, Band XIII Teil 4)

ISBN 978-3-443-14026-7, bound, price: 102.00 €

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Keywords

plantanatomyAngiospermous HydrophytesLemnaceaeduckweeds

Contents

Content Description top ↑

Hydrophytes, that are aquatic or subaquatic vascular plants, represent a class of plants extremely variable, but at the same time extremely heterogeneous in terms of their systematic position, the variability of their habitats and their modes of life.

A direct consequence of that heterogeneity is the wide range of anatomic peculiarities of hydrophytes, which is very hard, if not impossible to capture in a single volume. It was, therefore, chosen to treat three families of hydrophytes, Lemnaceae (Duckweeds), Hydrostachyaceae and Podostemaceae. They differ most markedly from terrestrial plants, notably by having a partly or completely thalloid vascular system. These families turned out to be a lucky choice, as their morphology has developed (or rather preserved) aberrant structures which force the question of their evolution to be asked anew.

A model which explains the observed features as extreme adaptions, tacitly implies that these aquatic plants were initially terrestrial plants which have returned to an aquatic habitat, instead of plants which survived in the aquatic or 'amphibious' environment they originally evolved in. This question of origin must be asked for all major adaptions, such as the diverse types of heterotrophy observed in phanerogams; the answer may be found looking at the biogeography or ecological conditions, but most likely these questions may not be answered by studying the anatomy of these plants.

Contents top ↑

I. Anatomy of the Lemnaceae (duckweeds). By E. LANDOLT, Zürich
Abbreviations 1
1. Introduction 1
1.1. History of the Lemnaceae investigations; literature 1
1.2. Human importance of Lemnaceae 2
1.3. Taxonomic organization 4
1.4. Systematic position within the monocotyledons 7
2. Organization and structure of the Lemnaceae 8
2.1. Appearance and structure of the plant body 8
2.2. Interpretation of the frond 18
2.3. Mode of growth; growth rate 23
2.4. Life-span and ageing; position and number of daughter fronds 23
3. Growing fronds 28
3.1. Shape, size, and weight 28
3.2. Colour and brightness 29
3.3. Elements of the normal cell 31
3.4. Specialized cells 37
3.5. Epidermis, stomata, and papules (papillae) 40
3.6. Meristematic and parenchymatic tissue; air spaces 49
3.7. Nerves and tracts of elongated cells; vascular and sieve elements 56
3.8. Pouches (pockets) and cavities protecting daughter fronds 64
3.9. Connection between mother and daughter frond (stipe) 64
3.10. Devices of stabilization 67
3.11. Roots 69
3.12. Prophyllum in Spirodela 76

4. Resting fronds 77
4.1. Appearance, size and shape; anatomical features 77
4.2. Tolerances of turions against environmental conditions 80
4.3. Factors causing formation and germination of turions 80
4.4. Ecological significance of resting fronds and turions 81
5. Flowers and fruits 82
5.1. Aspects of flowering fronds; position and number of flowers 82
5.2. Flowering organs; formation of flowers 85
5.3. Flower prophyllum 88
5.4. Stamens 89
5.5. Pistil 92
5.6. Interpretation of the flowering organs 94
5.7. Pollination 95
5.8. Fruit development 97
5.9. Fruits and seeds 100
5.10. Germination of seeds 106

5.11. Ecological significance of seeds 107
6. Ecology and distribution in relation to morphological and anatomical
characters 108
6.1. Ecological significance of morphological and anatomical features 108
6.2. Ecology and distribution 111
Acknowledgements 116
Bibliography 116
II. Anatomy of the Hydrostachyaceae
By I. JÄGER-ZÜRN, Königstein
Introduction 129
General plant structure 130
1. Vegetative structures 133
1.1. Germination 133
1.2. Stem 135
1.3. Leaves 140
1.3.1. Anatomy of leaves 144
1.3.2. Emergences of leaves 148
1.3.3. Developmental morphology of leaves 152
1.4. Roots 154

1.4.1. Root tip 158
1.4.2. Root-borne shoots 158
2. Floral structures 159
2.1. Inflorescences 159
2.2. Flowers 161
2.2.1. Female flower 161
2.2.2. Male flower 165
2.2.3. Bracts 168
2.3. Embryology 169
2.3.1. Female embryology 169
2.3.2. Embryo 175
2.3.3. Seed 177

2.3.4. Male embryology 177
3. The systematic position of the Hydrostachyaceae 181
3.1. Points of view for a higher order classification of Hydrostachyaceae on
account of new data 183
3.1.1. Embryological data 183
3.1.2. Flower morphological data 184

3.1.3. Cladistics 186
3.1.4. Myxospermy 186
3.1.5. Palynological data 186

3.1.6. Phytochemical data 187
3.1.7. Phylogenetic relationships based on molecular data 188

Addition in proof 191
Acknowledgement 192
Genus Hydrostachys: List of species and synonyms 192
References 193
III. Anatomie des Podostémacées [III. Anatomy of the Podostemaccae]
1. Par R. A. A. SCHNELL, Paris

1. Introduction [Introduction] 197
1.1. Généralités [General views] 197
1.2. Historique [A historical recall] 199
1.2.1. Les travaux anciens [Past works] 199

1.2.2. Les travaux récents [Recent wurks] 200

1.3. Aspects taxonomiques [Taxonomical features] 202

1.3.1. La question des Hydrostachyacées [The Hydrostachyaceae
question] 202
1.3.2. Le cas des Tristicha [The case of Tristicha] 202
1.3.3. Subdivisions des Podostémacées [Subdivisions in the
Podostemaceae] 203
1.4. Les affinités des Podostémacées [Affinities of Podostemaceae] 203
1.4.1. Dans le cadre des flores actuelles [with the present floras] 203
1.4.2. Une origine très ancienne? [An ancestral origin?] 204
1.5. Traits morphologiques généraux [Main morphological features] 205
2. Morphologie de l'appareil végétatif [Morphology of the vegetative body] 207
2.1. Ontogénie. La »racine« [Ontogeny. The so-called root] 207
l 2.2. Développement de la »racine« [Root development] 211
1 2.3. Le thalle. Ses structures [The thallus and its structures] 214
2.4. Les feuilles [The leaves] 216
2.4.1. Divers types morphologiques [Various morphological types] 216
2.4.2. Les feuilles de nature thalloïde [The thalloid-like leaves] 216
2.4.3. La feuille de Mourera fluviatilis [The leaf in Mourera fluviatilis] 220
2.4.4. Variations de la feuille au sein d'un même genre [Leaf variations
within the genus frame] 224
2.4.5. Les microphylles [The minute leaves] 224
2.4.6. La feuille du Tristicha [The leaf in Tristicha] 224
3. Anatomie de l'appareil végétatif [Anatomy of the vegetative body] 224
3.1. Le tissu général [The fundamental tissue] 224
3.2. Les éléments sécréteurs [The secreting cells] 227
3.3. Les appendices du thalle [The thallus appendices] 228
3.4 Les émergences des Mourera [The warts in Mourera] 230

3.5. Interprétation des structures précédentes [Interpretation of the above
structures] 233
3.6. Les thalles très finement divisés [The carved thallus] 237
3.7. Les thalles très divisés issus de Racines thalloïdes« [The carved thallus
from thalloid roots] 238
3.8. Feuilles à rôle absorbant chez les espèces à microphylles [Absorbing
leaves by microphylles-bearing species] 238
3.9. Trifurcations et pseudo-dichotomies [Thrce-forked twigs and false
dichotomies] 238
3.10. Les nodules de silice [The silice partiales] 240
3.11. L'accumulation d'amidon [The starch storage] 241
3.12. Les stèles [The steles] 242
3.13. La gaine des stèles. Collenchyme et sclérenchyme [The sheath:
collenchyme and sclerenchyme] 243
3.14. Les trachéides [The tracheids] 244
3.15. Le phloème. Historique [The phloem] 248
3.16. Les recloisonnements dans les stèles et le phloème [Cell partitions in
steles and phloem] 249
3.17. Conclusion sur les stèles [Conclusion regarding the steles] 251
4. La fleur et le fruit [Flower and fruit] 251
4.1. La fleur [The flower] 251
4.1.1. Localisation des fleurs [Location of the flowers] 251
4.1.2. Structure générale de la fleur [General flower structure] 252
4.1.3. Le périanthe [The perianth] 255
4.1.4. L'androcée [The androcaeum] 256
4.1.5. Le gynécée [The gynecaeum] 256
4.1.6. L'anthèse et la pollinisation [Anthesis and pollination] 26(
4.2. Le fruit [The fruit] 26
4.3. Les graines et leur dispersion [Seeds and their dispersal] 262

4.4. Le cycle annuel (Yearly cycle] 270
5. Les Podostémacées et le milieu [Podostemaceae and environment] 271
5.1. La nutrition [Nutrition] 271
5.2. Ecologie des Podostémacées [Ecology] 271
5.3. L'action de l'homme sur les Podostémacées [Man impact] 272
5.4. Biagéographie des Podostémacées [Biogeography] 273
6. Conclusion générale [General conclusions] 274
6.1. Les problèmes [The problems] 274
6.2. Les feuilles primordiales de la plantule [Seedling primitive leaves] 275
6.3. Le problème des plantes ancestrales [The question of ancestral plants] 275
6.4. Les faits chorologiques et l'hypothèse d'une origine gondwanienne
[Chorology and supposed Gondwanian origin] 276
6.5. Le problème des relations possibles entre les formes à
microphylles et les structures thalloïdes [Presumed relationships
between microphylles stems and thalloid structures] 277
6.6. Résumé synthétique [Synthetic summary] 278
Bibliographie [References] 279
General Index 285