Genetic Garden

The Parks’ Genetic Garden commemorates the contribution to genetics of Professor Cyril Dean Darlington, Director of the John Innes Institute and the Sherardian Professor of Botany, Oxford from 1953 to 1971.

Cyril Darlington established his reputation as one of the foremost researchers in the field on chromosome studies at a time when the chromosomal basis of heredity was not universally accepted. He promoted the fundamental (but then novel and highly contentious) belief that genetics could illuminate every branch of biology.

Among other things he revolutionised the teaching of the plant sciences in Oxford and parallel to, but separate from, the Botanic Garden (which was founded and arranged on a purely taxonomic basis) he began to establish a Genetic Garden. 

Darlington started thinking about creating a Genetic Garden almost as soon as he arrived in Oxford in 1953. He asked the University for space to create a garden funded and maintained by the Botany Department, and was given the space to the rear of 9/10 South Parks Road. This was planted in 1957, and was developing well when the University decided to demolish the houses to make way for a new science building. 

Darlington approached the Curators of the University Parks about relocating the garden, and, after some negotiation, they agreed to surrender a tennis court behind the Botany glasshouses in the Science Area. In 1964, this was fenced off, to be accessed only from the Science Area and used only for teaching; it was maintained by Botany. The new garden was laid out in formal beds, with groups of plants arranged in relation to areas of interest for teaching and research.

In 1998, the Genetic Garden was redesigned, replanted and opened up to visitors. Mature trees and shrubs planted in 1964 were retained, and herbaceous plants and bulbs from Darlington’s 1964 scheme were replanted, although laid out in an informal style. Other plants of (then) more recent genetic interest were added.

After another 25 years, the Genetic Garden again needs to be recreated, taking account of developments in plant genetics. Over the past two years, the Parks Superintendent has worked with a group of eight botanists and biochemists to produce an entirely new plan for a garden that will provide teaching space for undergraduates, and an illustration of interesting plant genetics for visitors, including children.

As the garden matures, visitors will be able to learn interesting facts about hybridisation and plant breeding, genetic variation and the environment, grafting, and what plants can do and still survive when things go wrong.

Below are some of the subjects that will be illustrated in the rejuvenated garden:

Hybridisation and plant breeding

Malus (apples) on different rootstocks will demonstrate plant breeding and grafting. Crops like wheat and barley will demonstrate changes over time as breeding has improved yields.
We will include hybrid plants planted next to their two parents, for example, Forsythia x intermedia and its two parents F. suspensa and F. viridissima as well as the Osmanthus hybrid, O. x burkwoodii, and its two parents O. delavayi and O. decorus. With osmanthus, it is possible to see the intermediary at all stages, while in forsythia, the intermediate characteristics are seen at leaf and flowering stages.

Dianthus were early candidates for hybridisation, using Sweet Williams, Dianthus barbatus, and carnations, Dianthus caryophyllus. The Oxford University Herbaria has the first 1717 hybrid, which was a milestone in plant breeding.

Genetic variation and the environment

Ecogeographical variation in junipers will illustrate variation in the sizes of mature plants.

Sexual dimorphism

This is the condition where different sexes of the same species look very different. We will illustrate this with variegated holly, where male and female flowers are on completely different plants, which look very different and yet are genetically the same species. This feature gave rise to an interesting quirk in the naming of hollies: Ilex ’Silver King’ is female while I. ’Silver Queen’ is male; in the golden variety the name reversal also occurs. 

Domestication

Dahlias, chrysanthemums and tulips all show a massive range of variation, all selected from the wild form, but now showing little resemblance to the original wild forms. A significant advantage in planting dahlias and chrysanthemums is that they flower early in the Michaelmas term, so are well-timed for teaching undergraduates. There is also good herbarium material, which is also useful for teaching Botany.

B chromosomes

B chromosomes are additional (or supernumerary) chromosomes that are not essential for the survival of a species, found in some plants, fungi and animals (including all mammals). Although B chromosomes do not carry essential genes, they can influence the genetic characteristics and adaptability of the organisms that possess them. We will illustrate these effects using chives, Allium schoenoprasum and Tulbaghia violacea.

When things go wrong

It is interesting what plants can do and still survive when things go wrong. This is illustrated by both variegated and contorted plants.