Bristlecone Pine: A Novel Conifer with an Ancient History
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The bristlecone pine (Pinus aristata) is a plant with an ancient history that continues to enhance residential landscapes today. Known as one of the oldest living trees in the United States, bristlecone pines range from 1,500 to 2,500 years of age. Its durable wood allows it to stand intact for hundreds of years until its root system decays. This characteristic has permitted scientists to assemble an historical timeline using the tree rings of both living and dead bristlecone pine and its close relative Pinus longaeva that dates back 10,000 years. The tree rings not only provide insight into past climatic conditions but also assist in calibrating accurate carbon-14 dating.
The native habitat of this pine is located on the climatically harsh eastern ridges of the Rocky Mountains extending south from Wyoming to New Mexico. The plant's survival depends on its ability to overcome extreme temperature changes, deficient amounts of water, and exposure to strong winds. Rather than growing taller, these plants focus on existing in a harsh, arid environment. Bristlecone pines grow only .01-inch in trunk girth each year and a mere 30 feet in height in a lifetime. The roots maximize water absorption by growing shallow and extensive systems in the alkaline, rocky terrain. The needles have also adapted by exuding a waxy layer to reduce evaporation and prevent desiccation in the arid winds.
Bristlecone pine, also known as foxtail pine, retains its needles for several years creating a distinct "foxtail" bushy needle and branching habit. This form adds picturesque structure to the winter garden when used as an accent plant in the landscape or in a mixed border. An easy way to identify Pinus aristata is by examining its needles. If you see resin forming tiny white dots on the needles, you are looking at a bristlecone pine. The white resin on the green needles creates a bluish cast over the entire plant.
In the residential landscape, bristlecone pines grow 8 to 20 feet with an irregular spread. They can survive a broad range of soil types in USDA Hardiness Zones 4 to 7, but do not tolerate shade. In the landscape, bristlecone pines are suitable when used as an accent plant or in a rock garden.
At Reiman Gardens, see a bristlecone pine used as an accent plant in a northern mixed border in the Dunlap Courtyard.
Jennifer Gray Nunez, Reiman Gardens, (515) 294-2710, firstname.lastname@example.org
Jean McGuire, Continuing Education and Communication Services, (515) 294-7033, email@example.com