25 



recruitment may not be detrimental to the 

 persistence of populations. Population size 

 may be buffered by the long-lived nature of the 

 plants. 



Pollination. 



a. Mechanisms: Astragalus barrii is probably 

 dependent on insects for pollination. 



b. Specific known pollinators: None known. 



c. Other suspected pollinators: None known. 



d. Vulnerability of pollinators: Not known. 

 Seed dispersal. 



a. General mechanisms: The pods of A. barrii 

 are deciduous, and may roll or blow about, 

 aiding in seed dispersal (Roberts 1977) . 

 Pods dehisce from the base upwards along 

 both the dorsal and ventral sutures 

 allowing for seed release. 



b. Specific agents: Not known. 



c. Vulnerability of dispersal agents and 

 mechanisms: Not known. 



d. Patterns of propagule dispersal: 



Populations and subpopulations generally 

 have a clumped distribution, which may be 

 due to localized seed dispersal, although 

 other factors such as substrate 

 availability ma^ play a major role. 



Seed biology. 



a. Amount and variation of seed production: 

 Apparently only one seed reaches maturity 

 within each pod of A. barrii (Barneby 

 1964) . 



b. Seed viability and longevity: Unknown. 



c. Dormancy requirements: Unknown. 



d. Germination requirements: Scarification 

 appears to enhance germination of A. 

 barrii seeds (Locklear 1987) . 



e. Percent germination: Unknown. 



