Nature Notes From Crater Lake - Volume 22, 1956
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Boggy places are well known to the botanist as the habitat of carnivorous plants. Perhaps "carnivorous" is a little strong here, for it implies that the plants eat meat; "insectivorous" is more appropriate. The reason usually given for the relative abundance of such plants in bogs is that bog soils are poor in nitrogen, an element essential to all living things; nitrogen is a substantial constituent of protein, which animals possess in abundance. If a plant can become adapted to obtain its nitrogen from some animal source, then it can flourish in places where the salts of this element in the soil are absent or in low quantity.
Several rather extensive sphagnum ("peat") bogs are found in the northwestern part of Crater Lake National Park. One of the most interesting of these, in the vicinity of Crater Spring, south of the Crater Spur Motorway, I became acquainted with on July 27, 1956. On this date, a number of us made a trip into this boggy region to gather information on the fauna and flora; the story of this has been reported on elsewhere by Ranger-Naturalist John Wirtz.
One of the abundant insectivorous plants in the area was the mountain bladderwort, Utricularia intermedia Hayne; its small yellow flowers were conspicuous here and there in patches on the surface of the shallow water. The bladderworts possess small but complicated bladder-like traps, with which they capture crustaceans, aquatic insects, and occasionally other tiny animals. Also, growing abundantly in the sphagnum were two species of sundew, the round-leaved, Drosera rotundifolia L., and the long-leaved, D. anglica Huds. Almost solid mats of these covered large parts of the marshy area, the leaves appearing red because of the myriads of reddish, sticky-tipped hairs which line their upper surfaces. The hairs are glandular, the tips provided with a flypaper-like secretion which entraps insects or occasionally other minute animals.
One of the abundant groups of insects in these boggy areas is that of the butterflies of the family Lycaenidae, the small kinds commonly called "blues." As is habitual with many butterflies, one or more species of "blues" may often be seen hovering in a little cloud about a small wet space or other spot, numbering from a few to hundreds of individuals. I was not surprised then, to find on a single plant of Drosera rotundifolia, five little blue butterflies, each hopelessly entangled by the sticky secretion of the glandular hairs. One of the five was being shared with a leaf from an adjacent plant, the individual plants growing so closely together that it was difficult to segregate single plants. I took the five hapless butterflies, all but two of which appeared to be alive yet, and when I return to the laboratory, identified them. Four I determined to be Plebeius acmon West. and Hew.; the fifth, a closely related species, P. battoides Behr. What an easy way for a butterfly collector to obtain his specimens!