Extrafloral Nectaries on Luffa Leaves

Did you recognize the big yellow flower from the Wordless Wednesday post with the carpenter bee? This might give you a hint:

It was from a luffa or sponge gourd, Luffa aegyptiaca (previously named L. cylindrica.)

Why were the ants on the underside of the flower in the last photograph of that post? It turns out that the luffa plant has been crawling with rover ants, even before it started to flower.

For a clue, let’s look at the underside of the luffa leaves. What are those green bumps on the leaf surface between the veins?

You might wonder if they are the leaf openings called stomata, but the stomata are the smaller dots.

Close up the bumps look like tiny green volcanoes.

Those are extrafloral nectaries, or EFNs. Extrafloral nectaries are nectar-producing glands found in areas of the plant outside of the flowers. Extrafloral nectaries occur in at least 66 different plant species and vary in size, shape and placement. The type of found in luffa are called “button-shaped.”

Like the nectar produced in the floral nectaries, extrafloral nectar is a liquid solution of sugar in water, with trace amounts of amino acids. The nectar attracts many different kinds of insects, but ants are often the most common visitors. The ants often chase away or capture plant-feeding insects, thus protecting the plant.

This means we can add luffas to the list of plants that might be useful for gardening for ants.

For more information, see:

Vivek Mohan Agarwal and Neelkamal Rastogi. 2010. Ants as dominant insect visitors of the extrafloral nectaries of sponge gourd plant, Luffa cylindrica (L.) (Cucurbitaceae). Asian Myrmecology, 3, 45–54. (free .pdf available at the “Read full PDF” link after the abstract.)

Have you seen the journal Asian Myrmecology? Currently the articles are offered for free online at the website.

12 Replies to “Extrafloral Nectaries on Luffa Leaves”

  1. This was a great article to let me know why the ants are coming – being attracted to the Luffa. But the ants are also eating off the plant where they are trying to create flowers. There are one or two ants at nearly every single joint (where the leaf comes in). First it was the little black ants (name unknown), but the ant trap I laid out did the charm. Now however, there is a larger black and red ant that has come in their place. Still, not one flower, because they are chowing down all throughout the day and night. I’m open for suggestions to remove this ant, but not necessarily kill them. I know neem oil doesn’t work – I spray on my plants as preventative every couple month, because of huge pest problems I have had in years past. I may just be resolved to remove the plants or just watch them grow with no fruit all season long. LOL . This is an aquaponics system and I refuse to use poisons. Deterrents – let’s go. bT however is not going into my garden!

  2. Are you absolutely sure?

    Other than leafcutter ants, there aren’t many kinds of ants that chow on plants. Instead, they eat the caterpillars and other bugs that attack plants. Ants get a bad rap because caterpillars and slugs — the true culprits that are eating the plant — often hide during the day.

  3. I am having the same issue. Over 3 months of beautiful plants with no flowers while my other squash have already been producing fruit. Little black ants are all over the joints where the flowers and new growth are coming from. Am going to try some diatomaceous earth to see that helps.

  4. Ants are probably not the issue, but if you want to make sure, putting a band of something sticky, like double-sided tape or Tanglefoot (https://www.tanglefoot.com/), around the base of the plant will likely keep the ants off it.

  5. I’ve planted luffa plants and small soon gourd plants this year (planted at the same time, in the same vicinity). The small spoon plants have yielded gourds out the wazoo, while no luffa plants have even started to flower. I’m not too worried yet, I know they have different expected harvest durations.
    The spoon plants, along with my zucchini and yellow squash plants, have been nearly wiped out by a squash bug infestation. Interestingly, the squash bugs haven’t touched the luffa plants. I’m curious if the medium-size black and crawling all over my luffas have protected them from the squash bugs, or if the squash bugs are not generally interested in luffa plants (or both?). Maybe they’re not interested in the luffas because they haven’t started flowering yet?
    Anyway, as long as the ants aren’t doing any harm I’m going to keep them around.

  6. I hope someone has found the answer! My luffa plant ( god was only able to keep one alive and growing after 2 failed atempts and 2 packets of seeds!) now I have a gorgeous plant with many bud clusters but they are all covered with about 6 ants each that look like they are searching for something AND THE BUDS, as soon as they are a teeny bit open get chewed off!!!! Any solution to this ( organic only)?

  7. I have the same issue! At first I thought the ants were beneficial – and they may mostly be. But at the same time they’re sucking the sweet sap off my luffas theyre sucking them dry and the tiny flower buds are yellowing before they open. Im sad I have to get rid of the ants because I love watching them dance all over the plant. They’re so happy! But now I realize they’ve got to go. Im hoping to hear that someone had luck with diatomaceous earth?

  8. It is the ants chewing off the future flowers. I have had some success spraying organic ant deterrent over the past few years. It’s happening this year as well. I just came back fro. The garden.

  9. Those of you who are losing flowers, are you willing to try an experiment? Put some sticky material like Tanglefoot or even vegetable oil around some of the stems to keep away the ants. Leave others alone. This is called an “ant-exclusion experiment.”

    I suspect you might find out that the ants aren’t the culprits, and that lack of pollination (female flowers that aren’t pollinated fall off) or herbivores might be the real cause. The plants have extrafloral nectaries to lure ants into getting rid of pests, so you see the ants and assume they are the problem.

  10. I also have lots of ants. First the black ants. Now the bigger redder ones. Lots of them. I am wondering if there is a point that it may be too many. They don’t seem to harm the plant though. There were female flower buds turn yellow. I don’t think it’s the ant. Otherwise it would be all the flower buds. I think it’s the consecutive above 90 degrees heat for the 4th week that did it. A few days of afternoon rain cool it. I can see it coming back to life. I did tried in the past with success to rid of the ants that were eating my peas flowering buds. I used dry turmeric powder n mixed in optional cinnamon or Szechuan peppercorns whatever I had available. Then sprinkle the powders on the plant. U would need to reapply after rain. I found it from YouTube. It really worked. It doesn’t harm the plant or any other pollinators.

  11. I have same problem with all kinds of ants and no flowers. Ants were building little sand piles in the joints of my cow peas so I wonder if they are doing the same with the luffa

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