Nevada. However, a form near Salmon, Idaho, is palatable to deer. The form near 

 Salmon is intermediate in morphology between A. tripartita and A. tridentata spp. 

 Wyoming ensis (E. F. Schlatterer, letter 12/1/77). 



Subspecies . --Artemisia tripartita ssp. rupicola (Wyoming threetip sagebrush) is a 

 dwarf shrub with decumbent branches that rarely grow over 1.5 dm tall. It is frequently 

 found layering and may have a crown spread of 3 to 5 dm (Beetle 1960) . Leaves of the 

 vegetative branches are often 3 cm long and deeply divided into linear lobes, each at 

 least 1 mm wide (Beetle 1959, 1960). Flower heads bear 3 to 11 disc flowers and are 

 arranged into leafy, narrowly racemose panicles. Flowers bloom in late August and 

 September. Seed ripens in October, Wyoming threetip sagebrush has a rather limited 

 range. It occurs on rocky knolls from 2,430 to 2,740 meters (7,000 to 9,000 feet) in 

 elevation in central and southeast Wyoming (Beetle 1960) . Brunner (1972) reported this 

 subspecies also occurs in southern Oregon but has not yet been found in Nevada, It 

 typically grows on sites adjacent to those of mountain big sagebrush. 



Artemisia tripartita ssp, tripartita (tall threetip sagebrush) is a freely branching 

 shrub up to 2 meters high. It can layer easily when the conditions are right, but is 

 seldom found layering in the field. After burning, it may stump-sprout (Beetle 1960), 

 Leaves of the vegetative branches are 1,5 to 4 cm long and deeply divided into 3 linear 

 lobes less than 1 mm wide. The lobes may be further divided (Beetle 1959, 1960). Flower 

 heads bear 4 to 8 disc flowers and are arranged into panicles that may sometimes be re- 

 duced to a spicate form. Flowers bloom in late August and September. Seeds ripen in 

 October. This subspecies occurs in dry, well-drained soils at 900 to 2,300 meters 

 (3,000 to 7,500 feet) elevation from British Columbia south through Washington to 

 northern Nevada and eastward to northern Utah and western Montana. Its type locality 

 is listed as "Plains of Rocky Mountains" (Beetle 1960) . 



Artificial hybridization in section Tridentatae of Artemisia 



Our experiments in hybridizing Artemisia section Tridentatae were undertaken with 

 plant improvement in mind (McArthur and Plummer 1974; McArthur and Pope 1975). The 

 section contains many taxa with different combinations of traits. We think some of 

 these traits such as growth form, palatability , adaptation, protein and volatile oil 

 content, and vegetative spread might be brought together in various combinations for 

 the land manager's benefit. 



The experiments were designed to determine: (1) Does hybridization occur and if so 

 (2) can it be controlled, and (3) to what extent are section Tridentatae plants self- 

 fertile? These questions are, of course, all interrelated. We have referred to 

 evidence for hybridization under each species that has been discussed. This evidence 

 is in the form of morphological and chemical intermediates. More definite evidence is 

 available. We have found triploid and pentaploid seedlings at the Snow Field Station 

 (McArthur and Pope, data on file at the Shrub Sciences Laboratory, Provo, Utah). The 

 best explanation for their occurrence is that plants of different polyploid levels 

 hybridized. The Tridentatae are mostly wind pollinated, a condition that gives oppor- 

 tunity for hybridization. Estes (1968) presented solid cytological, morphological, 

 and pollen stainability (an indication of pollen viability) data for hybridization in 

 the A. tudovioiana complex. Estes' (1968) hybrids included some interspecific hybrids. 

 On the other hand, Persson (1974) produced intraspecif ic hybrids in the A. maritima 

 complex, but she was not able to produce any interspecific hybrids. 



Controlled hybridization of sagebrush (section Tridentatae) is no easy matter. 

 The small perfect flowers are impossible to hand emasculate. Our attempts to induce 

 male sterility by using hot water and the ethelyne analog, Ethrel , were not successful. 

 The hot water treatment at 40° and 45° C for 2, 5, and 10 minutes stopped all seed 

 development when applied just prior to flower head opening. Higher water temperatures 



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