Beautiful, but deceitful and poisonous!

What is beautiful, but deceitful and poisonous?  This blog usually focuses on things biological, so it must be an animal or a plant, and perhaps it could be either.  In this case it is the oleander shrub that fits that description.

Nerium oleander flowers

Beautiful pink flowers of the highly poisonous oleander 

Oleander is such a popular addition to roadside plantings and gardens that it now occurs world-wide in warm, wet Mediterranean type climates where its long-lasting profusion of white, pink, or red flowers brighten up the landscape.  It is remarkably drought-tolerant and protects itself from being munched by herbivores by sequestering toxic cardiac glycosides in its tissues, from its roots to the tips of its leaves.  No wonder it’s the dominant plant along freeways in California.

Large milkweed bug on Nerium oleander flowers

An indicator of oleander’s toxicity is the presence of insects, like the large milkweed bug, with warning coloration feeding on flower parts and seeds.

Oleander is, in fact, one of the more poisonous plants, but mammals, especially humans seem to be more sensitive to its toxins than birds.  However, folk tales about drifters during the Dust Bowl years dying from having stirred their stew with oleander twigs are probably false.

Clearly, oleander is beautiful and poisonous, but what about being deceitful?  How can a plant be deceitful?

Nerium oleander flowers

Oleander flowers are brightly colored, sometimes fragrant, with a central opening meant to entice pollinators to explore.

But oleander flowers produce no nectar, and thus there is no reward for pollinators to keep exploring the profusion of flowers on the plant.  It’s false advertising and deceptive on the part of the plant.  But does it work, that is, does enough pollination occur to allow seeds to be produced?

flowers and seed pods of Nerium oleander

How many flowers with no nectar reward will a pollinator visit before it gives up and moves on?

Apparently, insects that pollinated this oleander explored many of the flowers in a cluster, moving enough pollen to produce several seed pods.  But the number of seed pods on the entire plant is scanty.

flowers and seed pods of Nerium oleander

Only a single pod was produced in this group of flowers

The only good news for bee pollinators is that the lack of nectar in the flowers means they would not contaminate their honey with cardiac glycoside poisons.

12 thoughts on “Beautiful, but deceitful and poisonous!

    • I didn’t either, but got curious when I saw the milkweed bug on there and wondered if it would lay eggs on the plant when there were so few pods present. Then I wondered why there were so few pods when there were soooooo many flowers. And so it goes…always another question.

  1. Algumas pessoas já usaram os seus paus para fazer espetadas e saíram-se muito mal, é preciso ter muito cuidado.

    Translation: Some people have already used their sticks to make skewers and they have done very poorly, you have to be very careful.

  2. Not many of the modern cultivars of oleander produce seed. They were bred to not do so because they seed pods and seed are undesirable. However, the breeding also deprived oleanders of their fragrance. There are a few old oleanders about that are still fragrant, but they can be a bit messy with their seed. There are also some that produce seed without fragrance. Sadly, oleanders are not as common as they once were. Many are succumbing o disease.

    • Actually, since it is an introduced plant, I’m glad oleanders aren’t very fertile. They seem to be vigorous growers that establish a large footprint even without sexual reproduction. Thanks for the info, Tony!

      • I have only found seedlings a few times. they are quite rare. They can grow like weeds here, but do not proliferate like weeds.
        Sadly, while working with some old specimens just yesterday, I found what looks like scorch. I know that it is a problem nearby.

        • Interesting! Well, other than the problem of the paucity of products of sexual recombination, it seems oleander has done quite well just surviving with vegetative reproduction. And if the plant is as drought and heat tolerant as research indicates, it will survive whatever the climate throws at it, I guess.

        • I certainly hope so. It was such a tough and reliable plant for so long. Now, so many are succumbing to the scorch disease. I happened to notice a weird batch in a nursery recently. I remember them because I had not seen any in such a while. I did not look at them because they were that pale white that looks almost yellowish orange (that I do not like so much). Now, I am thinking that I should have looked at them to see if they were a new cultivar that is resistant to the scorch disease.

  3. Pingback: Florida flowers: The ornate oleander – Midnight Harmony

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