I have two asplenium nidus, about four years old, in separate beds in a climate controlled atrium(72 degrees, 50% humidity). Both were thriving, upright, unblemished plants until a few days ago. One suddenly sagged badly literally overnight. The new rubbery growth was wilted, with the last few inches of the fronds kinked down like a dog's broken ear. After a few days, the mature fronds are beginning to droop downward as well, more noticeably at the frond tips. There is no discoloration or blemish anywhere. I have cared for these plants for over a year, and their growing conditions have not changed. Adjoining plants are normal, and the other fern is normal as well, so I am mystified. Any ideas appreciated. Thanks