Volume XXII - 1956

Among the adventurously inclined, flower hunting may seem a poor substitute for arctic exploration or hunting elephants. Searching for aquatic flowering plants in Crater Lake, however, has an element of excitement which we believe greatly exceeds the general impression of such endeavor. Besides the exhilaration of just being on Crater Lake with its beautiful water encircled by the sheer cliffs of the caldera, the scarcity of flowering aquatics in the lake makes new discoveries especially rare and thrilling. Until recently only four species, occurring in small isolated colonies, were known (Rowles & Fairbanks 1954). Another intriguing factor is the great depth at which plants generally occurring in shallow water are found in this lake.

Drawing made from the whorl-leaved milfoil collected in Crater Lake.

During the 1956 summer, after searching much of the shore area of Crater Lake, we located a spot to the northwest of Wizard Island which seemed to have a colony of plants of some kind growing on the rocky bottom. Grappling for the suspected plants in 20 to 25 feet of water was a slow process due to a wind which greatly reduced visibility and made boat operation difficult. After several unsuccessful attempts we brought up a water-milfoil, a plant which had never been reported before in Crater Lake National Park.

There was no doubt that the new plant was water-milfoil and belonged to the genus Myriophyllum, for this genus is a distinctive assemblage of plants. Determination of the species was more difficult since keys to species of Myriophyllum depend in large part upon flowers, fruits and emergent leaves and we had only the submerged leaves and stem (Fig. 1). Our new plant could be any of the three major species in Oregon: American milfoil (Myriophyllum exalbescens Fernald), whorl-leaved milfoil (M. verticillatum L.), or western milfoil (M. hippurioides Nutt.).

The morphological features of the submerged leaves, such as the number of leaf whorls at each node and the number of leaflets per leaf, and the reported ecological distribution of these three species were compared with the Crater Lake plant by Richard McP. Brown, assistant park naturalist at Crater Lake National Park, Doctors J. W. Moore and T. Morley, Department of Botany, University of Minnesota, and ourselves. We have each independently concluded that Myriophyllum verticillatum is the most likely possibility, although a more positive identification must await the acquisition of emergent leaves and flowering material.

References

ROWLEY, JOHN R., and FAIRBANKS, C. WARREN, 1954. "Aquatic flowering plants of Crater Lake." Nature Notes from Crater Lake 20:36-39.

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!