Hydrangea on varying amounts and access to aluminum ions

Hydrangea bloom colours, determined based on acidity or basicity of soil is a thing, yes. Unlike most plants, hydrangea colours don’t dependant and very on change of multiple pigments absorbing and reflecting light energy, but however they depend and change based on varying amounts and access to aluminum ions in the soil. Hydrangea flowers are much like litmus paper for a gardener, their colour changing solely on pH level of the soil.

This means that they are not necessarily a bloom of true flower, they are known more formally as an inflorescence.  Hydrangea flowers in a more acidic environment of soil, tend to obtain a more bluish colour due to the mobility of aluminum ions in an acidic environment. Upon reaching a threshold of 40 micrograms per gram however, once blue they do not get ‘bluer’. In an environment below threshold they reach a lavender colour where the hydrangea roots are receiving aluminum for that blue tint but not an excess amount.

Keep in mind a hydrangea exceeding threshold aluminum can kill the plant.  In a more basic solution of soil, the aluminum ions combine with hydroxide ions, making the product aluminum hydroxide ion. An ion which is immobile. Results of this is the hydrangea picking up a red/pink colour. However, in a very basic, hydroponic soil, tetrahydroxoaluminate is formed, and changes stability allowing for the ion to flow an act as if it were an aluminum ion.

In quick summary of understanding: RED= No Aluminum; BLUE= threshold reached;PURPLE= intermediate amount below threshold but aluminum is still available.  Now, Hydrangea due obtain one pigment. Delphinidin-3-glucoside. Found under the pigment family anthocyanins, it is the same group as pigments found in autumn leaves that change them red/orange. Delphinidin-3-glucoside is made up of a three carbon ring, various sugars connected and is low in pH level.

The pigment, with loss of one or more hydrogen ions, changes in levels of pH.   I chose to use this article as a relation to the biochemistry unit, because we covered a lot of topics and experiments involving identifying acids and bases, and determining pH level. I found it interesting how the article was able to not only teach the differences of acidity and basicity in the environment of these blooms but also how it works to effect the changes in their colourful bloom. Information found in this article was very interesting, I personally had no idea that a beautiful bloom such as this was based so solely on biochemistry and lacked in pigments and the usage of light energy for reflection and absorption. The best thing about using this article is that i was able to relate, compare, and learn facts, at a level I can completely understand. It provided the information that I needed but at a reasonable level of understanding.  Because this article is so based on the chemistry and reactions that change in pH level can result in, it made it a great opportunity for me to use this as a comparative article to the information i learned in biochemistry.

In the biochemistry unit I remember doing a lab on different acids and bases, we tested them for their different pH levels, to see how they would react and change the colour of the litmus paper, and what type of changes they could make in reactions. I find there is a lot of relation in that lab and how the hydrangea blooms work because we used litmus paper to obtain our results, and the hydrangea blooms work as an environments litmus paper in a way. They naturally change based on acidity and basicity. On top of that we also covered the chemicals of life, and the main organic chemicals of life consist of carbon, oxygen and hydrogen.

WIthout these the plants wouldn’t be able to do their job. I clued into this when i realized that the more basic solutions ionize and become aluminum hydroxide, and also that the structure of delphinidin-3-glucoside is a three carbon ring. I got thinking and put into assumption that if the only pigment, and the soil hadn’t obtained some of the key organic chemicals of life, that the hydrangeas would not be working in the way that they do today. They would lack this and consumption of aluminum would be different too.

Because aluminum bonds with a hydroxide ion, if that O, and H were not available that soil would not be basic and would likely prevent from any hydrangea to bloom in the colours of red through pink.  In conclusion, without biochemistry hydrangea plants would not bloom as uniquely as they do currently, and likely would result in different reactions.