UNIFORM GARDEN STUDIES ON THE ARTEMISIA TRIDENTATA NUTT. COMPLEX IN INTERIOR BRITISH COLUMBIA
The behavior of Artemisia tridentata ssp. tridentata and A. tridentata ssp. vaseyana in uniform gardens at Kamloops, Nickel Plate, and Greenstone as well as in some natural habitats supported the separation of the two subspecies. Kamloops (1140 ft) is located in the typical habitat of ssp. tridentata and Nickel Plate (5600 ft) represents the typical habitat of ssp. vaseyana.In their natural habitats ssp. vaseyana flowered about 2 weeks earlier than ssp. tridentata and their flowering periods did not overlap. In the Kamloops uniform garden ssp. vaseyana collections showed two distinct flowering patterns considered to be two ecotypes. The ssp. tridentata collections from the outer edge of the distribution of the subspecies flowered 1 week earlier than collections from the center of the range.Most of the ssp. tridentata plants set out in the Nickel Plate garden died within 3 years but most survived in the one at Greenstone. Almost one-half of the plants of ssp. vaseyana died in the Kamloops garden, mostly during the summers, except for the Nickel Plate material, which appeared more hardy. About 40% of the United States ssp. tridentata killed out in the local tridentata environment (Kamloops), mostly over winter.Leaves of ssp. vaseyana plants were typically wider than those of ssp. tridentata but leaf lengths were variable and not a good diagnostic character. The ssp. vaseyana plants had a spreading-decumbent growth form while ssp. tridentata plants grew more upright.