Flower Behavior in Linum lewisii: Some Ecological and Physiological Factors in Opening and Abscission of Petals

Flower behavior, particularly petal abscission,, of Linum lewisii was observed in the field and laboratory of the Rocky Mountain Biological Laboratory, Crested Butte, Colorado. Flower opening is primarily a response to light but is slower when temperatures are low. Normally the flowers open until the petals form an angle of 180?. If cut flowers are desiccated slowly, the distal 1/3 of the petals recurve strongly beyond 180?. Flowers close during the afternoon of the day of anthesis. Petals are weakly attached and can be readily dislodged by mechanical factors. Petal abscission occurs sporadically from midafternoon of the day of anthesis through the following morning; and can be hastened by wind or rain. Petal abscission is sensitive to temperature and moisture supply. It is accelerated by abscisic acid and retarded by indoleacetic acid. The evidence indicates petal abscission in L. lewisii involves the synthesis of hydrolytic enzymes in the abscission zone in a manner similar to? that of leaf abscission.