The University College Dublin ‘Evolution of Land Plants’ garden

The UCD ‘Evolution of Land Plants’ garden is an outdoor classroom designed to teach land plant evolution at University College Dublin (UCD). It first showcased at Bloom in the Park 2016, the Irish version of Chelsea Flower Show, where it won a Gold medal and Best Concept Garden, before being installed at UCD.

The idea for the garden was conceived by Assoc. Prof. Paul McCabe, Head of Botany, UCD. It was designed and created by Dr. Caroline Elliott-Kingston, Lecturer in Horticulture and Crop Physiology, UCD and Ms. Nicola Haines, Tierney Haines Architects.

The garden is visually divided into five sections from left to right. Each section represents a different time period from circa 600 million years ago (mya), when no plants lived on land, to present day. Each section contain a land and fresh water area, divided by a timber frame, and Sections 2-5 showcase a major innovation in land plant evolution.

The first timber column on the left in Section 1 (600-500 mya) contains the words ‘Before land plants’. This area has no land plants but contains freshwater algae (Chara sp.) in the pond.

Section 2 ‘Cuticle’ (500-400 mya) illustrates the first major innovation, the beginnings of a waterproof coating that allowed plants to move out of fresh water onto land without desiccating. It contains mosses and liverworts (Bryophytes).

Section 3 ‘Vascular tissue’ (400-300 mya) depicts the origination of ‘internal plumbing’ (xylem tissue) to transport water up through plants from roots to tips, allowing them to grow tall for the first time. This area contains ferns and horsetails (Pteridophytes).

Section 4 ‘Seed’ (300-200 mya) illustrates the origination of seeds. Before this, plants reproduced only by spores. This section contains conifers and cycads (Gymnosperms).

Section 5 ‘Flower’ (200 mya – present) showcases the variety of flowering plants (Angios
perms) that dominate Earth. Each section contains plants from the previous sections to explain that these plant types still exist.

Plants did not provide colour on land, other than varying shades of green, until flowers evolved. The final section bursts with colour to show how plants use flower colour and scent to co-opt animals, insects and birds into dispersing their pollen and seeds. Almost all food on Earth for both humans and animals is provided by flowering plants so this section includes horticultural fruit and vegetable crops and cereals.

Each section has a pond that diminishes in size as visitorswalk along the evolutionary path to depict plants’ diminishing reliance on water for successful reproduction over evolutionary time. They still require water for growth of course.In contrast, the land area in each sectionexpands from left to right, to illustrate the increasing diversity and expanding number of species on Earth over the past circa half billion years.

Corten steel panels are attached to the timber frame in sections 2 to 5. Each panel includes an animal that existed on Earth at that time. There is no panel behind the first section to show that there were no animals on land before plants as plants are the basis of all food webs on Earth. The panel position on the frame gets higher as one moves along the path to show that plants have generally got taller over evolutionary time.

When ‘walking through evolutionary time’ in this garden, it is hoped that students and visitors will better understand the major innovations in land plant evolution that allowed plants to colonise Earth and led to the wonderful greening of our planet. The garden is open to all to visit.

 

Article by:

Caroline Elliott-Kingston Dip. Hort., BSc.Botany, PhD, MCIHort

Nicola Haines BSc.Arch, Dip.Arch, RHS Level 3 Hort