A graphical representation of a frost event at the Rocky Mountain Biological Laboratory (Colorado). The temperature dipped to 25.1 F on 11 June 2004. Winter snowpack melted at the monitoring location on 8 May that year. The late-spring frost killed flower buds that had developed in the four weeks following snowmelt.
A flowering plant of Helianthella quinquenervis (aspen sunflower, Asteraceae) at the Rocky Mountain Biological Laboratory(RMBL). This species has flower buds that are frost-sensitive. The plants have a mutualism with ants, which are attracted by extrafloral nectar secreted by the bracts that cover flower buds.
Ants (Formica obscuripes) searching for extrafloral nectar on the involucral bracts around a flower head in bud in the frost-sensitive herb Helianthella quinquenervis. The ants help to deter oviposition by flies (Tephritidae) that try to lay eggs on the flower heads. Because fly larvae eat developing seeds, the ants benefit the plants. Thus, the ant / herb interaction represents a mutualism....
A meadow with thousands of plants of Helianthella quinquenervis (aspen sunflower, Asteraceae) at peak bloom. This species is a common long-lived perennial plant in meadows near the Rocky Mountain Biological Laboratory. This photo was taken during a year without frost damage. Compare the presence and density of sunflowers with the photograph of the same meadow in a year when frost damage killed...
Photo of a meadow with thousands of Helianthella quinquenervis (aspen sunflower, Asteraceae) plants. In the year that this photo was taken, a springtime frost killed all but a few flower buds. Compare with the photo of the same meadow in a year without frost. The lack of flowers in years having springtime frost has ecological consequences. There is no pollen or nectar for pollinators (bees and...
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