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Tag Archives: extrafloral nectaries

Wild words : extrafloral nectary

03 Wednesday May 2023

Posted by sconzani in insects, plants

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Bracken, extrafloral nectaries, nectaries on Bracken, nectary, Pteridium aquilinum

Nectary: noun, biology; ‘a nectar-secreting glandular organ in a flower (floral) or on a leaf or stem (extrafloral)’ (Oxford Dictionary).

230503 extrafloral nectaries (1)

Like most people, I knew that most flowers produce nectar as a reward to attract pollinators but I’ve only recently learned that many plants produce nectar through extrafloral nectaries, as the definition explains, on their leaves or stems. I read that these particular nectaries can be found on many species of fern, and I’ve finally found some examples on the stems of Bracken (Pteridium aquilinum) that has just begun to sprout locally. The nectaries are the small smooth pale lumps on the back of the stipe, and, in Bracken, their purpose is apparently to attract ants that will then defend the fern against the insects that might eat it, like some species of bug and fly, and the larvae of various moths, amongst others.

230503 bracken and ant

ant leaving nectary on Bracken

However, I also found a journal article, referenced below, which reported that the ants actually had ‘no significant effect on bracken-specific herbivores’ so, in this case, the plant may be producing nectar for nothing.

Reference: ‘Bracken, Ants and Extrafloral Nectaries. I. the Components of the System’, J. H. Lawton and P. A. Heads, Journal of Animal Ecology, vol. 53, no. 3, October 1984, pp. 995-1014. I do not have access to Jstor so was only able to read the information contained in the article summary.

230503 common froghopper nymphs

Common froghopper nymphs on Bracken

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The Brimstone, the vetch and the ants

20 Friday May 2022

Posted by sconzani in flowers, insects, wildflowers

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Tags

ants, ants nectaring on EFNs, Brimstone, Common vetch, EFNs, extrafloral nectaries, Grass vetchling, nectar sources on plants, Vetches, Vicia species

Two for the price of one today: a lovely female Brimstone butterfly, which I was really happy to catch feeding on Common vetch.

220520 vetch and ants (1)

But, lurking beneath the flower, you may be able to spot a small creature. It’s an ant and, if you’ve ever looked closely at the flowers of any of the vetch family (Common, Bush, Tufted, and the vetchlings), you may have noticed they all prove attractive to ants.

220520 vetch and ants (2)

I’ve only recently discovered the reason for this: these plants all have extrafloral nectaries (EFNs), tiny glands on the stems and other areas of a plant, where nectar is secreted. The vetches aren’t the only plants to have these EFNs – according to a report on the University of Florida website (and there are many other scientific papers online, if this subject intrigues you), EFNs have been found in over 2000 plant species. Scientists don’t seem completely sure why plants ‘feed’ ants in this way, though it may be a means of rewarding ant species for their protection against the plant-munching larvae of other insect species.

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About me

sconzani

sconzani

I'm a writer and photographer; researcher and blogger; birder and nature lover; countryside rambler and city strider; volunteer and biodiversity recorder.

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