Fossil fuel embedded energy is still photosynthetic in origin. Terrestrial plants, on the other hand, tended to form coal and methane. Many of the coal fields date to the Carboniferous period of Earth's history. Terrestrial plants also form type III kerogen, a source of natural gas. There is a wide range of organic, or hydrocarbon, compounds in any given fuel mixture. The specific mixture of hydrocarbons gives a fuel its characteristic properties, such as boiling point, melting point, density, viscosity, etc. Some fuels like natural gas, for instance, contain only very low boiling, gaseous components. Others such as gasoline or diesel contain
The Private Life of Plants it makes use of almost no computer animation. The series also discusses fungi, although as it is pointed out, these do not belong to the kingdom of plants. The mechanisms of evolution are taught transparently by showing the advantages of various types of plant behaviour in action. The adaptations are often complex, as it becomes clear that the environment to which plants must adapt comprises not just soil, water and weather, but also other plants, fungi, insects and other animals, and even humans. The series shows that co-operative strategies are often much more effective than predatory ones, as these often