5.7.3 TRUNKS
Although the trunks of some tropical rainforest trees have special characteristics such as fluting, they tend to have very similar smooth, light-coloured cylindrical shaped trunks. As the crown and leaves of a mature emergent tree are well out of sight, species can often only be distinguished by making a slash through the outer and inner bark of the trunk with a machete. The colours, texture, odours, taste and the presence or nature of exudates can then be used to identify the tree.
For instance, L.G. Cooper describes Terminalia superba (White Afara) as having a light yellow slash, and Lophira procera (Iron Wood) as having a hard, red slash, often showing a yellow powder under the outer bark.
5.7.4 LEAF, FLOWER AND FRUIT FORMS
The trees of the tropical rainforest show an incredibly wide variety of leaf, flower and fruit forms, far too many to be listed here. However an interesting feature of tropical rainforest trees (and rarely found elsewhere) is Cauliflory, whereby flowers and fruits occur on leafless woody trunks and branches (such as cocoa), and sometimes even on aerial roots.
It is also worth noting that flower and fruit forms may be elaborately adapted for pollination or seed dispersal by animals. The mass of vegetation makes pollination or dispersal by wind an ineffective strategy, especially in the middle and lower layers where wind rates are negligible, thus bats, of all the animals are essential in this respect.
5.8 BIODIVERSITY OF THE LEM RAINFOREST
The dynamics of the natural tropical rainforests exhibit the essence of ecosystems on the grandest scale: finite supplies of nutrients are efficiently recycled in a highly energetic system. These rainforest ecosystems are the most bioactive and biomassive on earth, and this is the key to their biodiversity.
Species evolution into more diverse forms is like a fast breeder nuclear reactor: the more species there are in an ecosystem, the more interaction there will be both within and between species, resulting in the evolution of yet more species that in turn feed the process. The bigger the gene pool, the greater the number of possible gene combinations, and the greater the chances of a useful genetic mutation.
Genes, Inheritance, Mutation And Evolution
Genes: are the basic units of inheritance—they are sometimes described as hereditary units. They are passed on from parent to progeny in a conservative but imperfect way; this is what makes evolution possible.
Genetics is the study of genes and their interactions, heredity and variation; it is a massive, demanding and complex area of scientific enquiry.
Inheritance: characteristics such as flower colour or skin tone are inherited by an organism from its parents, through information carried by the genes. However the expression of these genes will then be affected by the environment within which an organism develops (for example, the child of tall parents will not grow to be tall herself unless she is well fed).
Patterns of inheritance are complicated by the fact that one set of genes for all traits are inherited from each parent, so that any given individual will normally have