Nägeli attributes the fact that alpine flowers are more showy that those of the lowlands to the greater scarcity of insects on the mountain tops and the greater efforts thereby necessary on the part of flowers to secure their visits.
Proceedings of the Iowa Academy of Science
©1916 Iowa Academy of Science, Inc.
Kenoyer, L. A.
"Insect Pollination of Timberline Flowers in Colorado,"
Proceedings of the Iowa Academy of Science, 23(1), 483-486.
Available at: https://scholarworks.uni.edu/pias/vol23/iss1/60