As a plant, my primary mechanism for attracting pollinators is through the offering of rewards, namely nectar and pollen. From this fundamental perspective, the Oleander (Nerium oleander) presents a complex case. I produce a significant amount of nectar, a high-energy sugar solution that is a sought-after food source for many flying insects and birds. This nectar is stored deep within my floral tubes, which are the elongated structures at the base of my petals. Therefore, the potential for attraction exists based on the promise of a valuable nutritional reward.
However, my entire being—leaves, stems, flowers, and even the nectar itself—contains potent cardiac glycosides, such as oleandrin. These are powerful toxins that I synthesize as a defense mechanism against herbivores. This toxicity creates a major barrier for most potential pollinators. While the nectar is energy-rich, it is also laced with these compounds. This means that for many species, the nutritional benefit is outweighed by the potential harm, making me an undesirable and dangerous food source. My chemical defense, while excellent for my survival against predators, significantly limits my appeal in the pollinator community.
The question of attraction is not a simple yes or no; it is a matter of specificity. Generalist pollinators like the European Honeybee (Apis mellifera) may initially be attracted to my showy, colorful clusters of flowers and will occasionally forage on my nectar. However, they are not my primary or preferred pollinator. My relationship is more specialized. I have evolved to attract and be pollinated by insects that have a tolerance for my toxins. Certain caterpillars of moths, like the Oleander Hawk-moth (Daphnis nerii), have developed a resistance to my cardiac glycosides. They can feed on my leaves without harm, and the adult moths are effective pollinators. Therefore, I do not attract the broad suite of pollinators but rather a select few adapted to my unique chemical profile.
Regarding butterflies, the relationship is minimal. Most butterflies are sensitive to toxins and will avoid my flowers in favor of safer, non-toxic nectar sources. The same principle applies, even more strongly, to hummingbirds. While my trumpet-shaped flowers might suggest a fit for their long beaks, the toxic nectar is a significant deterrent. Hummingbirds have very high metabolisms and are extremely vulnerable to toxins. Consuming my nectar could be fatal to them. Consequently, hummingbirds instinctively avoid me, and I have not evolved any specific traits to attract them, as they are not a viable vector for my pollination.
In summary, from my perspective as a plant, I am not a significant attractor of bees, butterflies, or hummingbirds in the general sense. My showy appearance might initially draw in bees and the occasional butterfly, but my potent chemical defenses make me a poor and often dangerous food source for them. My ecological strategy is one of selectivity rather than universality. I attract a narrow range of specialized pollinators, primarily certain moths, that have co-evolved a resistance to my toxins. For the gardener seeking to support a diverse population of bees, butterflies, and hummingbirds, I am not a recommended choice. They would be far better served by plants that offer a safe, non-toxic nectar reward.
