|QUINN JAMES A|
|MOWREY DANIEL P|
|WHALLEY RALPH D|
Submitted to: American Journal of Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/1/1994
Publication Date: N/A
Interpretive Summary: Buffalograss is a major species of short-grass rangeland from central Mexico through Montana. It has been suggested that buffalograss invaded North America through the consumption and deposition of seed as the buffalo migrated northward. We investigated this hypothesis by feeding buffalograss seed to cattle then evaluating the digested seed. We found that passage of buffalograss diaspores through cattle had a positive effec on germination and seedling growth from intact diaspores, that damage other than that due to mastication (15%) was minimal, and that the retention time was 1-5 days. We suggest that this combination of retention time and free-ranging migratory herbivores during the northward expansion of the short-grass semi-arid grassland enhanced the migration of buffalograss northward to Montana from its area of origin in central Mexico.
Technical Abstract: Janzen proposed that the foliage of herbaceous plants may serve as the attractant for large herbivore dispersal of seeds, selecting not only for traits enhancing passage of viable seeds through the animal but also for the edibility of the plant's foliage. We tested this "Foliage is the Fruit" (FF) hypothesis by collecting (Buchloe dactyloides, buffalograss) and collating (Bouteloua gracilis, blue grama) data from the two dominant grasses of the short-grass prairie. We found that passage of buffalograss diaspores through cattle had a positive effect on germination and seedling growth from intact diaspores, that damage other than that due to mastication (15%) was minimal, and that the retention time was 1-5 days. Palatability of buffalograss, as indicated by closeness of grazing of male and female clones along transects, was high but showed no relation to sex, and lab analyses of foliage quality and digestibility confirmed the high quality of the foliage but again produced no consistent evidence for one sex being superior in attractiveness. After reviewing evidence that blue grama shows corresponding FF traits, dispersal by dung, and a northward migration from Mexico, we conclude that blue gram and buffalograss, which dominate major portions of the largest North American steppe Province, provide strong support for the FF hypothesis.