Internal factors in plant growth are mainly plant growth regulators, very similar to hormones in animals. These include:, Auxins, The most well-known one., Stimulates apical growth and fruit growth while inhibiting lateral meristematic growth., Present in small amounts, but as it is distributed evenly, has very noticeable effects on plants., Gibberellins, Similar to auxins in that they stimulate plant growth, except these are distributed equally throughout the plant., Cytokinins, Stimulate cell division and leaf mesophyll growth, Important in biotechnology for tissue growth stimulation., Ethylene, Is largely a contributor to ripening of fruit. Stimulates the process where the fruit becomes softer and more sugary as starch is converted to sugar., Abscisic Acid, Acts mainly as an inhibitor to control stomatal operations and mostly to induce dormancy to allow for survival in harsh conditions.
Light Requirements, Quality of Light Received, Impacted by angle of incidence, shade, cloud cover, time of day and differentiations between seasons., Quality of light impacts how well the plant can photosynthesize and how much it can., Quantity of Light Received, Impacted by the size of the plant, competition with other, larger plants, latitude and other factors., The more light the plant can receive the more it will be able to photosynthesize and the more glucose it will have at its disposal.
Soil Nutrients, Macronutrients, These must be acquired in large quantities., Carbon, oxygen and hydrogen are the main ones and are acquired through carbon dioxide and water., Other macronutrients include phosphorous, potassium and magnesium, Nitrogen is the most needed material in a plant other than water and carbon dioxide. This is obtained through nitrogen left in soil by dead matter, or nitrate ions created by bacteria in the soil., Micronutrients, These are only needed in smaller quantities., All play a vital role in plants, either as cofactors to make enzymes work or as part of important compounds., Some examples of these are boron, zinc and copper., Absence/lack of any nutrients will cause very serious deficiency in plants and sometimes death., Minerals are normally eroded from rocks and other objects nearby and go into the soil., Absorption, Positive ions are absorbed by plants when the root hairs emit H+ ions to switch places with the other ions to be uptaken by the plant., Negative ions are not held in the soil particles and thus are easier for the plant to uptake, but also easier to be washed away in heavy rain.
Budding, or growing a piece of the original plant producing a genetically identical clone as offspring, In this form of reproduction, the offspring cannot move very far
Pollen is carried from flower to flower by animals and/or wind to fertilize the ovules in other flowers, The gametes fuse and the ovule grows into a seed, The seed are protected by many things and adapted in many ways. Not all of these are present in every case:, Seed coat, The seed has a protective coat that protects it in its dormant stage. The seed will penetrate this when it is prepared to germinate (proper conditions are present)., Fruit, Fruits serve a double purpose in seed adaptation. They serve both as physical protection for the seed, and as a way to make seed dispersion more effective. They offer nutrients to animals that eat them, and put their droppings elsewhere containing the seeds., Waxy waterproof layer, Plants that thrive in/around water often have an extra waxy, waterproof coating to protect the seeds from pre-mature germination. Shown here are water lily seeds., Wing-like structures, Some trees such as the maple tree may have these to help the seed dispersion process., Parachute-like structures, Some plants such as the dandelion have seeds that have these to make the wind a very effective carrier in the seed dispersion process., Very specific germination conditions, Certain plants such as the Calvaria plant have seeds with very specific germination conditions. This plant's seeds would only germinate after passing through the digestive tract of the dodo.