Club member, Heather Spicer gave a fascinating presentation on the flora she saw on a recent trip to South West USA. She travelled to several National Parks in Utah and Nevada and was amazed at the variety of plants growing in extreme conditions. Heather was particularly impressed by the Creosote Bush, the Bristlecone Pine and Quaking Aspens. Each of these plants has adapted to desert conditions over many centuries and some specimens are considered amongst the oldest living organisms on earth.
Heather explained that the Creosote Bush Larrea tridentata, is an evergreen bush known for the distinctive odour of creosote emitted after rain. As the creosote bush grows older, its oldest branches eventually die and its crown splits into separate crowns. This normally happens when the plant is 30 to 90 years old. Eventually the old crown dies and the new one becomes a clonal colony from the previous plant, composed of many separate stem crowns all from the same seed.
The Bristlecone Pine Pinus longaeva, has a gnarled and stunted appearance. They often only have a small strip of living tissue connecting the roots to a few live branches. Live Bristlecone Pines have been dated to over 5,000 years old – a remarkable age for a tree growing in a harsh environment.
Quaking Aspens Populus tremuloides, propagates itself primarily through root sprouts, and extensive clonal colonies are common. As Heather explained, all trees in a given clonal colony are considered part of the same organism, one clonal colony, named Pando, is considered the heaviest and oldest living organism at six million kilograms and is approximately 80,000 years old.