1 Introduction.- 1.1 Prehistoric and Ancient Use.- 1.2 Changing Uses of Forests.- 2 Definitions and Descriptions.- 2.1 Introduction.- 2.2 Sapwood.- 2.2.1 Definitions.- 2.2.1.1 Sapwood.- 2.2.1.2 Included Sapwood.- 2.2.2 Area of Sapwood in Log Cross-Sections.- 2.2.3 Variation of Area of Sapwood.- 2.2.3.1 In a Species.- 2.2.3.2 In Different Species.- 2.2.3.3 Due to Age of Tree.- 2.2.3.4 Due to Rate of Growth.- 2.2.3.5 Due to Environment.- 2.2.4 Sapwood Contents.- 2.2.5 Discolored Sapwood.- 2.3 Intermediate Wood.- 2.3.1 Description.- 2.3.2 Occurrence.- 2.4 Transition Zone.- 2.4.1 Definition.- 2.4.2 Description.- 2.4.3 Occurrence.- 2.4.3.1 Heartwood Boundary Stain.- 2.5 Heartwood.- 2.5.1 Definition.- 2.5.2 Description.- 2.5.2.1 Appearance.- 2.5.2.2 Level of Maximum Area.- 2.5.2.3 Regular Heartwoods.- 2.5.2.4 Irregular Heartwoods.- 2.5.2.5 Variations in Appearance.- 2.6 Tree Exudates and Extracellular Materials.- 2.6.1 Definitions.- 2.6.1.1 Intercellular Secretory Spaces, Cavities, and Shakes.- 2.6.1.2 Intercellular Canals.- 2.6.1.3 Pitch Tubules and Stones.- 2.6.1.4 Pockets, Veins, and Streaks.- 2.6.2 Types of Exudate or Deposit.- 2.6.2.1 Resin.- 2.6.2.2 Gum.- 2.6.2.3 Kino.- 2.6.2.4 Latex.- 2.6.2.5 Manna.- 2.6.2.6 Amber.- 2.6.2.7 Balsam.- 2.6.2.8 Maple Sugar.- 2.6.2.9 Crystalline Compounds.- 2.6.3 Rate of Formation.- 3 Historical Aspects.- 3.1 The Use of Durable Woods.- 3.2 Exudates.- 3.3 Varnishes and Lacquers.- 3.4 Gums.- 3.5 Tannins.- 3.6 Dyes.- 3.7 Perfumes.- 3.8 Rubber.- 3.9 Medicines.- 3.10 Lessons from History.- 4 Influence of Forestry Aspects.- 4.1 Variation of Heartwood Volume.- 4.1.1 Heritability.- 4.1.2 Effect of Growth Rate and Crown Size.- 4.1.3 Influence of Environment.- 4.1.4 Influence of Injury and Health.- 4.2 Formation of Exudates.- 4.2.1 From Bark and Wood.- 4.2.2 From Wood.- 4.2.3 Addition of Stimulants.- 5 Chemical Features.- 5.1 Water and Gases.- 5.2 Inorganic Compounds.- 5.3 Storage Substances and Intermediates.- 5.4 Nitrogenous Compounds.- 5.5 Ethylene.- 5.6 Type of Extractives.- 5.6.1 Galactans and Cyclitols.- 5.6.2 Terpenoids.- 5.6.3 Fatty Acids and Related Compounds.- 5.6.4 Phenolic Compounds.- 5.6.4.1 Simple Phenols and Phenolic Acids.- 5.6.4.2 Lignans.- 5.6.4.3 Stilbenoids.- 5.6.4.4 Flavonoids.- 5.6.4.5 Quinones.- 5.6.4.6 Polymerized Polyphenols.- 5.6.4.7 In Different Tissues.- 5.7 Amount of Extractives.- 5.7.1 Position of Sample in the Tree.- 5.7.2 Effects of Rate of Growth 1ll.- 5.7.3 Effect of Site.- 5.7.4 Genetic Differences.- 5.7.5 Crystals.- 5.8 Reagents for Heartwood Detection.- 5.9 Exudates.- 5.9.1 Resin.- 5.9.2 Gum.- 5.9.3 Kino.- 5.9.4 Latex.- 5.9.5 Manna.- 6 Biological Features.- 6.1 Sapwood.- 6.1.1 Wood Tissues.- 6.1.2 Lumen Volume.- 6.1.3 Deposition of Extractives on Wall Surfaces.- 6.1.4 Impregnation of Cell Walls.- 6.1.5 Parenchyma.- 6.1.5.1 Volume.- 6.1.5.2 Cell Wall.- 6.1.5.3 Cytology.- 6.1.6 Respiration and Enzymes Activity.- 6.2 Transition Zone.- 6.2.1 Seasonal Variations.- 6.2.2 Appearance.- 6.2.3 Water Content.- 6.2.4 Pit Aspiration and Tylosis Formation.- 6.2.5 Cytology of Parenchyma Cells.- 6.2.6 Respiration.- 6.2.7 Enzyme Activity.- 6.2.8 Formation of Extractives.- 6.3 Heartwood.- 6.3.1 Seasonal Formation.- 6.3.2 Appearance.- 6.3.3 Respiration and Enzyme Activity.- 6.3.4 Location of Extractives.- 6.4 Wound Wood and Chemically Affected Wood.- 6.4.1 Wound Wood.- 6.4.2 Paraquat-Treated Woods.- 6.4.2.1 Biochemical Changes Due to Paraquat.- 6.4.3 Ethylene-Treated Wood.- 6.4.4 Knots.- 6.5 Exudates.- 6.5.1 General.- 6.5.2 Resin Formation.- 6.5.2.1 Anatomy of Pockets.- 6.5.3 Gum Formation.- 6.5.4 Kino Formation.- 6.5.4.1 Anatomy of Veins and Pockets.- 6.5.4.2 Chemistry of Kino Formation.- 6.5.5 Rubber Tapping.- 7 Function, Formation, and Control of Heartwood and Extractives.- 7.1 Function and Volume of Sapwood.- 7.1.1 Function.- 7.1.2 Volume.- 7.2 Types and Formation of Heartwood.- 7.2.1 Introduction.- 7.2.2 Types of Heartwood.- 7.2.2.1 Regular Heartwoods.- 7.2.2.2 Other Types.- 7.2.3 Conclusions.- 7.3 Features of Heartwood and Woundwood.- 7.3.1 Some Theories of Heartwood Formation.- 7.3.1.1 Natural Causes.- 7.3.1.2 Accumulation of Gas and Control of Water Content.- 7.3.1.3 Initiation by Fungi and Hormones.- 7.3.2 Anatomical Changes.- 7.3.3 Occurrence of Extractives.- 7.4 The Transition Zone and its Formation.- 7.5 Function of Extractives and Exudates.- 7.6 Formation of Exudates and Extractives.- 7.6.1 Differences in Composition.- 7.6.2 Site of Formation.- 7.6.2.1 Exudates.- 7.6.2.2 Extractives.- 7.6.3 Amounts.- 7.6.4 Type of Extractives in Tissues.- 7.7 Initiation of Formation of Heartwood, Extractives, and Exudates.- 7.7.1 Initiation by Displacement of Water.- 7.7.2 Initiation by Changes in Ethylene Levels and in Hormonal Balance.- 7.8 Factors Controlling the Nature of Extractives and Exudates.- 7.9 Activities at Cellular Levels.- 7.10 Conclusions.- References.

Heartwood and Tree Exudates

Occurrence and distribution of free flavonoid aglycones in plants

The systematic treatment and circumscription of the group of plants presently recognised as the genus Acacia has a complex history. The genus was first described by Philip Miller in 1754 and until 1842, when George Bentham clearly defined it's generic limits (by restricting the name Acacia to mimosoid plants having numerous free stamens), a number of species which are now referable to genera within tribes Ingeae and Mimoseae had been referred to it. As presently defined, Acacia is a cosmopolitan genus containing in excess of 1350 species and together with the monotypic genus Faidherbia Chev. (which occurs in Africa and the Middle East), comprises tribe Acacieae within subfamily Mimosoideae. The current classification of Acacia views the genus as comprising three large subgenera, namely subg. Acacia (c. 161 species, pantropical), subg. Aculeiferum Vassal (235 species; pantropical) and subg. Phyllodineae (DC.) Seringe (syn. subg. Heterophyllum Vassal) (960 species, largely confined to Australia). In 1986, Pedley proposed that these three subgenera be attributed generic rank, namely Acacia, Senegalia Rafinesque and Racosperma C.Martius, respectively, but this proposal was not widely adopted. Subsequently, the results of monographic and floristic works have greatly expanded knowledge, not only of Acacia, but also of its presumed relatives in tribes Ingeae and Mimoseae. Cladistic analyses of chloroplast genes have been especially informative in developing a better understanding of phylogenetic relationships of the group. The new data clearly show that the genus as presently defined (i.e. Acacia sens. lat.) is not monophyletic. Furthermore, five separate monophyletic groups can be recognised within Acacia sens. lat. and it is recommended that these each be recognised as a distinct genus. The five genera correspond to those recognised by Pedley, except that Senegalia sens. lat. is now regarded as comprising three genera, namely Senegalia sens. str., Acaciella Britton & Rose [based on Acacia subg. Aculeiferum sect. Filicinae (Benth.) Pedley] and an undescribed genus based on a group of species related to Acacia coulteri Benth. Acacia subg. Acacia appears to be located in tribe Mimoseae. The relationships of subg. Phyllodineae, subg. Aculeiferum sens. str., sect. Filicinae, the 'Acacia coulteri' group and Faidherbia are not fully resolved, although in all studies these groups are shown to be monophyletic. Although it is appropriate that each be recognised as a distinct genus, the application of the names Acacia and Racosperma is currently under consideration and it is therefore not appropriate to use these names until this matter is resolved.

Overview of the generic status of Acacia (Leguminosae: Mimosoideae)

Phytochemistry of Acacia—sensu lato

Publisher Summary This chapter discusses important sources of polysaccharides and their molecular constitutions. Two associated plant polysaccharides are the D-fructo-furanans and β-D-glucans containing mixed linkages. The association of lignin with polysaccharides through chemical linkages as well as in the form of physical incrustation is of profound economic importance in relation to the digestion of feedstuffs by ruminants and the exploitation of carbohydrate resources through enzymatic breakdown. Pectic substances or pectins have long been considered to include diverse types of polysaccharide structure based on appropriately linked units of D-galacturonic acid, D-galactose, and L-arabinose and are, like the hemicelluloses, of great economic importance. The capacity of a plant to assemble numerous sugar residues in an orderly matter must in some measure reflect certain genetic characteristics of the species concerned. The relationships of the hemicelluloses and pectic substances in primary cell walls to the polysaccharides available in abundance from tissues in developed, mature plant stuffs are interesting because the same economy of use of relatively few sugars linked in a limited number of ways is observed throughout. The presence or absence of minor structural features in a purified, homogeneous (or at least not demonstrably heterogeneous) polysaccharide preparation is of limited significance in the cases in which the isolation of the polysaccharide requires lengthy and involves physical and chemical extraction procedures.

Mary D. Tindale

Papers

A phytochemical survey of the Australian species of Acacia

An extended phytochemical survey of Australian species of Acacia: Chemotaxonomic and phylogenetic aspects