It has been postulated that differences in environmental conditions among hosts species existing at microsites influence spatial patterning of plant parasites. Distribution pattern among halophytic host species for the parasite, Cuscuta salina, is patchy at the Palo Alto saltmarsh in Northern California. The preferred host, among several halophytic host species, is Salicornia virginica. To test this hypothesis studies of the biotic and abiotic environments of host plant species were examined. Marked spatial heterogeneity was present within the biotic and abiotic environments of the three infested host species examined. Significantly different among the three host species were succulence of shoot tissues, salt accumulations on shoot surfaces as well as water contents of associated soils. Ionic accumulations in plant tissues also indicated spatial differences for specific ions. However, examinations of soil nutrients in soils associated with parasitic infestations as compared with soils of non-infested areas failed to indicate any spatial differences between the two soil types. The data presented here in this study suggest that parasitic host preference may indeed be influenced by spatial heterogeneity among host plant species and their associated soil environments.

Key words: parasite, plant and soil nutrients, plant host species, saltmarsh