What is Albinism?
Albinism is the hereditary absence of pigmentation in a plant or animal. The genetic traits for albinism are recessive.
Biological pigments are produced by living organisms. The wavelengths of light which are not absorbed by a particular pigment, therefore reflected instead, are what we observe as colour.
The main function of biological pigments in plants is photosynthesis. In this process a green pigment, chlorophyll, and several other red and yellow pigments are used to produce energy for the plant.
It is thought that albino seedlings result from a genetic mutation, whereas albinism in just the stems or leaves of a plant is thought to form through the mutation of a single or group of cells.
How to Identify Albino Plants
Visually, albino plants can be identified as the white forms of normally coloured plants. Albino plants have slower growth rates than their non-albino counterparts.
Albinism in plants can be identified at a molecular level by the incomplete differentiation of chloroplast membranes, and by the complete or partial loss of chlorophyll. This results in the plants ability to use light to photosynthesise, thereby produce energy, being compromised. This reduces its likelihood of survival.
Plants which are not albino
- Plants that have white parts such as flowers, which have some chlorophyll present, are not albino.
- Etiolated plants; plants that are pale from existing in dark conditions.
- Plants where the green colour is masked by a wax, for example some spruce trees.
How do Albino Plants Survive?
Albino plants can only survive if they are able to ‘steal’ nutrition from neighbouring plants, thereby becoming parasitic to that plant. For this reason the majority of albino plants can only take in a small amount of nutrients before dying. Most albino plants only last for several days, and are only able to survive this long by using the energy originally stored in the seedcase.
Albino plants cannot survive in direct sunlight as they do not have the pigmentation required to protect them from direct rays.
White variegation on part of a plant is due to that individual’s inability to produce chlorophyll in a particular area, this is a type of albinism. These types of plants are known as chimaeras due to their tissues having more than one type of genetic makeup.
Albino Redwoods – A Special Case
Albino redwoods have white needles, but despite this lack of chlorophyll they can grow to a large size as a parasitic plant at the base of an ordinary redwood tree. Albino redwoods are extremely rare, only approximately 60 examples are known of. There are even fewer examples of chimeric redwoods, meaning that they have both ordinary and white pine needles. As they are able to photosynthesise to some extent, chimera’s can grow to a larger size than albinos.
Redwoods are particularly successful as albino plants due to the way that they grow. Although redwoods are able to grow in various ways (from seeds, cuttings or stumps) the way that allows albino plants to survive, is through the growth of redwoods from the roots of a ‘mother’ tree. The trees grown in this way are thereby connected to one another via a shared root system. This allows any albino redwoods to take nutrition from other trees which have been able to photosynthesise.
Albino redwoods have been known to live up to 100 years, with the tallest observed specimen growing over 20 metres tall. The needles of an albino redwood not only differ in colour, they are also thinner, softer, more malleable and less waxy.
By studying albino redwoods, scientists are able to learn about the genetics of normal redwood trees. In chimera’s they can study how the absence of a gene affects a particular function of the plant.
Other Common Albino Plants
Albinism is observed fairly frequently in sweet cherry varieties, such as Hedelfingen, Bing and Black Tartarian.