Olive Inflorescence and Pollination

What are Olive Inflorescences?

Olive Inflorescences are the fruiting shoots of the olive tree. Each inflorescence will have 10 to 30 flowers, depending on the characteristics of the tree. As even amateur gardeners could tell you though, a flower doesn’t always grow into fruit.

Today, we’ll take a deep dive into the importance of Olive Inflorescences, Olive Buds, and How Olive Trees Are Pollinated.

Olive Inflorescences and Olive Tree Pollination

Each February, as the winter cold persists, olive trees across Italy begin to bud (called mignole in Italian). The buds grow through early spring and usually start to bloom in April and May. These beautiful blossoms are white with a yellow center.

Some of these flowers exist purely to release pollen that will pollinate other trees through the wind. Others will grow into the beautiful olive fruit that we know and love. And this whole process begins with the growth of the Olive Inflorescences.

What Are The Little Buds On My Olive Tree?

It’s likely that the little buds on your olive tree are the olive inflorescences – but they might also be the start of a new shoot. Either way, the buds grow in the leaf axil, which is the space between the leaf and the stem of the plant. These buds may be either flower buds (inflorescences) or vegetative buds.

Flower buds are buds that will grow into clusters of flowers, which could grow into fruit if pollinated. Vegetative buds, on the other hand, may grow into new shoots that will in turn grow their own leaves and inflorescences. When the buds first begin to grow, it can be hard or even impossible to determine what kind of buds are growing. Understanding which buds are which can only be discovered with time.

What Does An Olive Tree Blossom Look Like?

Olive buds look like ‘joyful’ little olives. Truly! Olive buds look like tiny little olives, usually growing together in small clusters. They aren’t yet olives though! As we’ve already discovered, the buds may be either flower buds or vegetative buds.

If the buds are in fact olive inflorescences, they should begin to bloom around mid-May to early June. The olive tree’s flower blooms are white with a yellow center and don’t have a scent. You may notice that not all of the olive blossoms look the same though. This is because the flowers vary depending on their sex.

Olive Blossoms: Staminate and Perfect Flowers

A staminate flower is a flower that only has a stamen (the male part of a flower). A perfect flower is a flower that has both stamen and pistil (the female part of a flower). The pistil is what may eventually grow into the olive fruit itself, and so only a perfect flower can grow into an olive. The staminate flowers still have an important role to play though!

The stamen releases pollen which may fertilize the pistil – either of its own tree or of another tree. Because both types of olive blossoms have stamen, one might think there is an overabundance of pollen. However, researchers believe that the presence of staminate flowers is actually beneficial. This is because they increase pollen output, meaning there’s a higher likelihood of pollination.

How are olive trees pollinated?

Olive trees are pollinated when the pollen is released from the flowers and transported from one plant to another. In some cases, a tree may also fertilize its own flowers. This process of pollination is vital for the life cycle of most plants; it is what makes it possible for trees and plants to be fertilized, and the consequent production of seeds and fruits.

Pollination occurs with the help of atmospheric agents (mostly wind!) and the incessant work of pollinating insects, birds and even bats. This magic trick is what regulates the earth’s flora and allows us to survive.

How Pollination Occurs: Wind-Pollination (Anemophily)

As we’ve said, the majority of olive pollination occurs thanks to the wind, a process known as anemophily. The wind can take pollen across very long distances – up to 1000km. However, it’s likely that the pollen is more viable if it arrives on a stigma quickly.

Wind-pollination is important because it enables cross-pollination to occur, which is when a plant’s flowers are fertilized by another plant’s pollen. Cross-pollination leads to more genetic variability (biodiversity), rendering a plant more likely to adapt and change. There is also some research to suggest that cross-pollination in olive groves may increase yield and fruit quality, although this may only be true for certain cultivar.

How Pollination Occurs: Insect Pollination (Entomogama)

Entomophilic pollination, or insect pollination, occurs with the help of insects and other flying species. Small insects go in search of the nectar produced by some flowers, sometimes immersing their body into the flower. As they do this, a flower’s pollen grains might stick to the insect’s body. The most famous example is of course the honeybee, whose tiny hairs enable it to quickly capture large amounts of pollen.

As the insect travels from flower to flower, it releases the pollen grains of one plant onto the next. When the pollen is transferred to the flower’s stigma, pollination occurs. This allows for the formation of fruit, or seeds, and can eventually lead to the birth of a new plant.

Olive Tree Pollination Types

There are many different olive cultivars, and not all cultivars are the same. Some are able to pollinate themselves, others require pollen from different cultivars for fertilization to happen. Ensuring olive trees have the right pollen available is vital for the growth and production of the tree.

We distinguished 3 different types of pollinators.

Self-Pollinating Olive Cultivars

A tree that self-pollinates is one that can, of course, pollinate itself! The pollen produced by the stamen can drop down onto the pistil’s stigma. In this case, the tree may grow fruit without the assistance of the wind or of insects and animals. That said, the movement caused by the wind or by an insect landing on the flower may help the pollen to drop from the stamen to the pistil.

Self-pollinating olive cultivars include Koroneiki, Arbosana, and Arbequina.

Self-Incompatible Olive Trees

A significant amount of olive cultivars are self-incompatible, meaning that they require the pollen of other cultivars for pollination to occur. This trait is believed to be a species’ natural mechanism to promote outbreeding, achieved through cross-pollination. As we know, this improves “genetic variability, and consequently evolutionary diversification”.

Some self-incompatible olive trees may be pollinated by a number of different cultivars. In fact, it is often thanks to the cross-pollination of self-incompatible trees that this type of olive tree can be pollinated and produce fruit.

Self-incompatible olive cultivars that can be pollinated by various other cultivars include Leccino, Nocellara del Belice, Peranzana, and Moraiolo.

Other types of self-incompatible olive trees, however, can only be pollinated by specific olive cultivars. These include Ascolana Tenera, Tonda Iblea, and Correggiolo

As you can tell, the process of creating delicious olive oil starts well before harvest. Of course, when it comes to Olive Inflorescences and Pollination, nature takes care of most of the work for us. It is vital for us to understand the process though, especially when it comes to the different types of pollinators.

We hope you learnt something new about olive tree pollination, olive buds, and olive inflorescences.

Of course, Olive Inflorescences and Olive Tree Pollination are just the start. If you’d like to learn more, don’t forget to explore our Olive Oil 101 Resources here.

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