What Is Tree Nectar and Why Do Trees Produce It?

Many people are familiar with maple sap, but trees also produce another sugary fluid known as nectar. This substance is a natural secretion distinct from sap, which primarily transports water and nutrients within the tree. Instead, tree nectar serves as a form of currency in the natural world, facilitating interactions between the plant and the animal kingdom.

Unveiling Tree Nectar: Composition and Creation

Tree nectar is a complex aqueous solution, primarily composed of sugars that provide an energy source for various animals. The main sugars are sucrose, glucose, and fructose, with their proportions varying between tree species. Nectar also contains trace amounts of other substances, including amino acids, proteins, and salts that contribute to its nutritional value.

Nectar is produced in specialized glands called nectaries. These can be located within the tree’s flowers (floral nectaries) or on other parts like leaves and stems (extrafloral nectaries). During this process, sugars from photosynthesis are transported to these glands, which then modify and release the solution.

The rate and composition of nectar production are influenced by several factors. A tree’s species, age, and health are primary elements, along with environmental conditions like temperature, humidity, and soil moisture. Some plants can even increase their nectar’s sugar content within minutes of a pollinator’s visit, demonstrating a dynamic response to interaction.

The Purpose and Producers of Tree Nectar

The primary purpose of floral nectar is to attract and reward animal pollinators. Since trees are stationary, they require a method to transfer pollen to reproduce. By offering a high-energy food source, trees entice animals like bees, butterflies, birds, and bats to their blossoms. As these animals feed, they brush against the flower’s reproductive parts, picking up or depositing pollen.

The relationship between a tree and its pollinator is a result of co-evolution, where both species adapt to suit each other. The nectar’s composition can be tailored to the dietary needs of a specific pollinator. For example, nectars for birds and bats often have different sugar ratios than those for insects, ensuring the most effective pollinators are drawn to the tree.

Beyond pollination, nectar can also serve a defensive role. Extrafloral nectaries, which are not involved in reproduction, attract animals that act as bodyguards for the plant. Ants, for instance, are commonly drawn to this nectar and, in return for the food, will defend the tree against herbivorous insects. Common nectar-producing trees include:

• Maples
• Apple and cherry trees
• Linden trees
• Willow trees

Tree Nectar’s Importance for Wildlife and Ecosystems

Tree nectar is an important food source that sustains wildlife beyond immediate pollinators. For many animals, this liquid provides energy for activities like flight and reproduction. Honeybees famously collect nectar to produce honey, their primary food store, but countless other insects, including wasps, flies, and moths, also depend on it. Birds like hummingbirds and various bat species also have diets heavily reliant on nectar.

The availability of tree nectar influences the stability of local food webs. By supporting pollinator populations, nectar ensures the fertilization of plants, leading to fruit and seed production. These fruits and seeds then become a food source for other animals, such as squirrels and bears, creating a cascade of nourishment through the ecosystem. The nectar-feeding insects also provide food for insectivorous animals.

This interconnectedness means a healthy supply of tree nectar contributes to overall biodiversity. Early-flowering trees, for example, provide sustenance for pollinators emerging in the spring when other food sources are scarce. This allows pollinator populations to thrive, which in turn supports the entire plant community and the animals that depend on it.