Flowers in all stages of bloom were studied at different locations to determine 

 which matured first, stigmas or stamens. No definite conclusion was reached. Both 

 organs may mature about the same time. Soon after the flower opens, the stigma 

 appears to be receptive and some of the outer stamens are starting to dehisce. 



Seeds are tightly held in the achene and are separated only by intense rubbing, 

 whereas, seeds of cliffrose relatives, antelope and desert bitterbrush (Purshia 

 glandulosa) readily separate from their achenes. Stansbury cliffrose averages 64,615 

 cleaned seeds per pound (142/g) (Plummer and others 1968) . 



Cliffrose has a chromosome number of n = 9 (Stebbins 1959) . 



Hybridization: Natural hybrids of Stansbury cliffrose crossed with antelope 

 bitterbrush (fig. 22) or desert bitterbrush are fairly common where the ranges of these 

 species overlap. 



A small population of putative Stansbury clif frose-Apache plume hybrids occurs 

 along Ranger Pass about 12 miles west of the Big Springs Ranger Station, Kaibab 

 National Forest, Arizona (fig. 23). Both parents also occur in this vicinity. This 

 population contains the only known natural hybrids between these two species. On 

 July 25, 1968, 72 seeds were collected from these hybrids and 16 (22.2 percent) 

 germinated. Only two of these seedlings grew into young plants. 



Artificial hybridization performed by treating emasculated flowers of Stansbury 

 cliffrose (fig 24) with pollen from Apache plume, antelope bitterbrush, and the 

 clif frose-bitterbrush hybrid has produced viable seed and seedlings (table 1). 



Viable seeds have also been obtained by artificially pollinating emasculated 

 flowers of bitterbrush, the bitterbrush-cliffrose hybrid, and pistillate flowers of 

 Apache plume with Stansbury cliffrose pollen (table 1). 



17 



