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January Gardener 2016

Updated: Sep 28, 2021

Science in the Garden

Extract from a talk given last November by Tony Arnold ACIHort to the Tatworth & District Horticultural Society (County of Somerset in England UK. )

The talk was motivated by questions frequently asked by gardeners and aimed to clarify possible confusion over many aspects of horticulture and related science The perception of scientists can be scary to many gardeners – but a little science knowledge can be useful to us all.

At the commencement of the talk the audience were shown a copy of the Royal Charter signed by Her Majesty the Queen in 2014 conferring Chartered status on the Institute of Horticulture


  • Plant names can be identified fairly easily worldwide by family, genus and species.

  • Plant structure, propagation and reproduction were covered in layman’s terms.

  • Nutrients and soils were one of the most frequently asked subjects for clarification.

  • Plant wellbeing and adaptation to weather and climate change were briefly discussed at the end of the talk.

Plants and trees are very special to us all and life without them would be unthinkable.

Some plants which were previously thought to be extinct have evolved from 200 million years ago. Examples recently discovered were the Ginko biloba in China, the Wallemi pine recently in Australia and the Metasequioa (redwood) was previously thought to be extinct. Modern day ferns are similar to prehistoric cycads. The Araucaria monkey puzzle tree has also successfully survived and evolved from prehistoric times.

Plant names and identification were covered in some detail, the difference between common names and botanical names being emphasised. Labelling and special horticultural terms were covered to help gardeners understand the differences between plant species. The importance of getting the appropriate cultivar was highlighted – size is important when buying a tree!

A quick quiz on common and botanical names was enjoyed by the audience and a short role play (thank you to Emma Down for taking part) explained that it is not necessary to use or commit to memory the Latin names of plants – just carry a small notebook and write down those of particular interest was best advice.

Plant family names are important to gardeners as plants in the same family have similar characteristics e.g. flowering, attraction to insects, similar soil pH and many others. Many different popular plant families e.g. leguminaceae (pea), and brassicaceae (mustard) are of particular interest to vegetable growers, but also have attractive ornamental species e.g. laburnum and sweet peas (leguminaceae) an eg stocks and aubretia (brassicaceae).

Other ornamentals covered briefly by the talk included the ericaceous (rhododendron), ranunculaceae (buttercup), caprifoliaceae (honeysuckle) and roseaceae (rose) families.

Tree families were covered looking for similar characteristics, e.g. if catkins, trunk width, height and canopy. Conifer families have many species but are easily divided between pines, cypress and redwoods and the single species araucaria (monkey puzzle tree).

Plant reproduction attracted a lot of interest – plants have a much more varied and complicated sex-life than humans!

Hybridising and grafting were explained. Hybrids are plants produced by crossing two different plants i.e. two genera or two species. The plants produced are often sterile but can be incredibly strong and robust.

Grafting plants together is a tremendously important part of horticulture used in modern day fruit and wine production.

One example of an unusual graft of particular interest to the audience was the combination of a cytisus grafted onto a laburnum, which results in a laburnocytisus which bears a complete mix of both flowers.

Nutrients and soil – the talk centered on the main point that many gardeners only have a rough idea of what is required for a good soil, what makes a perfect loam, and why in addition soil needs organic matter. The audience were passed a sample of soil dissolved in distilled (neutral) water together with a pH meter as an example of how gardeners could get a better idea of how to analyse their own soil. Plant soil pH was of great interest as many gardeners were already aware of the importance of pH requirements for certain plants.

Nutrients were covered with the importance of maintaining sufficient nitrogen, phosphorous and potassium. Plant foods were discussed e.g. solid and liquid and how these are taken up by a plant’s vascular system and converted to plant energy with photosynthesis and then respiration. Plant behaviour was also touched upon, with a lot of interest in plant hormones and the beneficial adding of seaweed.

Aquaponics was discussed as a very modern day method of propagating plants on an industrial scale, at home and, amazingly, in outer space, where experiments are being conducted at this very moment for RHS Schools Campaign.

Finally, the talk finished with a very brief discussion on plant wellbeing and adaptation to climate change, and how the rules of planting will be changing.


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