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Ants at nectaries on Bracken Fern
Ants (genus uncertain) at nectaries on Bracken Fern. The nectaries (better named as foliar- rather than extra-floral as ferns do not have flowers) are the small dark patches on the leaf stem.
"Bracken extrafloral nectaries secrete sugars and amino acids at low and variable rates. Nectar production increased rapidly to a peak in mid-June, then declined slowly to zero in late August. Seasonal patterns of ant activity on bracken fronds usually mirrored nectar availability." From J. H. Lawton and P. A. Heads (1984). Bracken, Ants and Extrafloral Nectaries. I. the Components of the System in Journal of Animal Ecology 53(3):995.
It has been speculated that the ant-bracken association is one of mutual benefit to both species but various studies over the years have shown that bracken-adapted insects are not seriously affected by the ants and have developed strategies to minimize being killed by the ants.
Distinguished from other Pteridium aquilinum varieties by the terminal segments of pinnules 2-4 times longer than wide; segment margins and abaxial surface of blade midrib and costae shaggy.
Petiole 15--100 cm. Blade broadly triangular to sometimes ovate, 3-pinnate or 3-pinnate-pinnatifid at base, 20--80 × 25--50 cm; blade margins and abaxial surface shaggy, rachises and costae glabrous or sparsely pilose abaxially. Pinnae (proximal) broadly triangular, distal pinnae narrowly triangular.. more
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