14 



and subsequent fertilization. In the 

 Orchidaceae, the anthers, containing the pollen 

 grains, are grouped in masses called pollinia. 

 When insects visit the flowers, they come into 

 contact with the viscidium, a sticky disk 

 connected by a stalk to the pollinia. The 

 viscidium adheres to the insect, taking with it 

 the pollinia, which can then be carried on to 

 another flower. However, in cases where a 

 flower is not visited by an insect, the 

 viscidium shrinks as the flower whithers, 

 pulling the pollen masses away from the anthers 

 to hang forward above the stigma. Wind 

 movement is then sufficient to bring the pollen 

 into contact with the stigma, and self- 

 pollination is thus achieved (Williams and 

 Williams 1983) . It is possible that self- 

 pollination is prevalent in C. passerinum . as 

 no insect visitors were observed during field 

 surveys in 1988. 



SEED DISPERSAL AND BIOLOGY: Upon maturation of 

 the capsules, the walls split upon drying to 

 release the numerous seeds they contain. The 

 seeds of orchids are very small, and are 

 typically dispersed by wind. 



It is well known that most orchids rely on a 

 symbiotic relationship with certain soil fungi 

 (mycorrhizae) for effective seed germination 

 and subsequent growth. If the necessary 

 mycorrhizal fungi are lacking at a particular 

 site, it is not likely that a species such as 

 C. passerinum could become established there. 

 Currently, some aspects of this relationship 

 are being studied by Ales Suchomel, a botany 

 student at the University of Montana. 

 Specifically, his study will include the sowing 

 of seeds onto artificially fungi-enriched 

 substrates in the field, in sites which appear 

 to be suitable habitat but which do not 

 currently support the species. Comparisons 

 with germination results on artificial media 

 will be made. 



G. POPULATION ECOLOGY 



1. BIOLOGICAL INTERACTIONS 



COMPETITION: Owing to its specialized habitat, 

 C. passerinum would not possess strong 

 competitive ability in other more densely 

 vegetated areas to which it is not ecologically 

 adapted. However, within the microhabitats 



