1. Invasive Horticultural Species  This presentation covers a few of the many invasive horticultural species in the United States. The emphasis of the slides reflects their original use for CA and AZ. Author: Richard W. Hoenisch WPDN Training and Education rwhoenisch@ucdavis.edu

2. Ailanthus altissima Tree of Heaven Native to China and introduced into California in the 1850s as a shade tree, as an important Chinese medicinal plant, and as a food plant for a species of silkworm. It was first introduced to Europe (France and England) by a French Jesuit priest returning from Nanking in 1751 for the manufacture of lacquer. It was introduced into the eastern US from Europe in 1784 as an ornamental.

3. Tree of Heaven Spreading by Suckers J. M. DiTomaso

4. Tree of Heaven Seed Production © 1995 Saint Mary's College of California © 2005 Luigi Rignanese

5. Tree of Heaven Propagation and Spread  Spread by seed and by creeping roots  325,000 + seeds per tree  Seeds last about 1 year  Seeds need 40 days of moisture to germinate  Dioecious – male and female plants

6. Tree of Heaven Seedlings © 2005 Luigi Riganese

7. J. M. DiTomaso Crimson Fountain Grass Crimson Fountain Grass reproduces from seed. Individual plants can live for 20 years or more. Seeds can last up to 6 years in the soil. Population increases in density after a burn.

8. Pennisetum setaceum Crimson Fountain Grass  Originally native to Africa and the Middle East, fountain grass has been introduced to many areas, including Arizona, California, Florida, Hawaii, Fiji, South Africa, and Australia. It has spread in large part because of its popularity as an ornamental plant. It is easily dispersed by vehicles, humans, livestock, and, over short distances, by wind, by water, and possibly by birds.  The remarkable spread of this species into a broad range of habitats in Hawaii is attributed to its ability to adapt. Hawaii is the perfect habitat.

9. Crimson Fountain Grass

10. J. M. DiTomaso Cultivars such as Rubrum, Cupreum, and Eaton Canyon do not produce viable seeds

11. 11 Buffel Grass Pennisetum ciliare  Introduced into AZ at Tucson as a forage grass in the 1930s with planting trials with the Soil Conservation Service between 1938 – 1952  Began to get out of control around 1984  Reproduces by seed, rhizomes, and stolons  Out competes native plants  A serious fire hazard Photo courtesy of the Arizona-Sonora Desert Museum

12. 12 Invasive Tamarisk Species  Saltcedar – Tamarix ramosissima  Chinese Tamarisk – Tamarix chinensis  Athel Tamarisk – Tamarix aphylla  Smallflower Tamarisk – Tamarix parvifolia J. M. DiTomaso Saltcedar in flower.

13. 13 Tamarix ramosissima Saltcedar, Late Tamarisk Mr. & Mrs. Robert G. Young. USDA NRCS Native to eastern Asia, it has an extensive root system with a high evapo-transpiration rate in arid climates. Block waterways & out-competes native vegetation. When dry becomes a serious fire hazard.

14. 14 Tamarix chinensis T. chinensis has naturalized over wide regions and is an invasive. It naturalizes aggressively and is a voracious consumer of water It is notoriously dangerous in fires because its resinous leaves burn explosively

15. 15 Tamarix aphylla Athel Tamarisk, Athel Tree, Flowering Cypress Athel Tamarisk is widely planted as an ornamental, especially in the South West, and is less invasive than the other species. Native to northern Africa, the Middle East, and India

16. 16 Tamarix parviflora Smallflower Tamarisk, Early Tamarisk A native of SE Europe, it is very invasive with very deep roots that can access deep soil moisture, drying up wetlands. Roots extract salts from deep under ground and excrete them through the leaves, thus raising the surrounding salinity.

17. 17 Tamarisk Identification T. parviflora Tamarix ramosissima J. M. DiTomaso T. chinensis

18. 18 Tamarisk Identification J. M. DiTomaso Foliage of athel tamarisk, T. aphylla, and saltcedar, T. ramosissima

19. 19 Tamarisk Propagation T. ramosissima seedlings T. ramosissima seed T. parviflora resprouting from stem fragment. J. M. DiTomaso T. ramosissima new saplings along creek bed Jose Hernandez