Hedera

Ivy is a green plant that stays green all year.

It can grow on the ground. It can also climb high up trees or walls.

Small roots help the plant stick to things.

Ivy makes tiny yellow flowers in the fall. These flowers have nectar for bees.

Many birds like to eat the dark berries. The birds spread the seeds to new places.

Many small bugs live in the thick leaves. Birds and tiny animals also build nests there. Ivy is a busy home for nature.

Ivy is a group of many plant species.

Most stay green all year long. They can grow on the ground. Some can climb very high. They can reach 30 meters up a tree or wall.

Young ivy stems use small roots to stick to bark or rock. Adult stems are thicker and do not need those roots.

Ivy flowers are greenish-yellow. They grow in groups called umbels. These flowers have lots of nectar. This helps many insects, like the ivy bee.

In late winter, the plant makes berries. These berries can be dark purple or black. Birds eat the berries and spread the seeds.

Ivy is a great home for nature. Many bugs live in the thick leaves. Small animals even build nests in the ivy. In some places, ivy can grow too fast. It may crowd out other plants in the forest. This is why people watch how it grows in North America.

Ivy is a group of many different plant species.

Scientists call this group Hedera. Most of these plants are evergreen. This means they stay green all year long. They can grow along the ground or climb up high. On flat ground, they stay very short. On a wall or a tree, they can climb 30 meters up.

Many people plant them to cover brick walls. This makes them very popular in gardens around the world.

These plants change how they look as they grow. Young stems are thin and flexible. They use small roots to stick to rocks or tree bark. This helps them climb toward the light.

When the ivy becomes an adult, the stems get thicker. Adult stems can support themselves without those little roots. The leaves also change shape. Young leaves have many points. Adult leaves are shaped like a heart. They grow in sunny spots high up on trees or rocks.

Ivy has a very long history in our world. Scientists think the group began in East Asia. The oldest fossils were found in Korea. These fossils come from the Oligocene epoch. Later, the plants moved west toward Europe.

People have used ivy for a long time. In Ancient Rome, people wore ivy wreaths. They thought it could help them stay sober. In the United Kingdom, ivy was often used to show where a pub was located.

There are many different types of ivy species. Some live in Algeria or the Canary Islands.

Scientists group them by the tiny hairs on their leaves. These hairs are called trichomes. Some species have scale-like hairs. Other species have star-shaped hairs. The plants also have different numbers of chromosomes. Some have 48, but others have as many as 192.

This shows how much variety is in the group.

Ivy is very important for many living things. The flowers are greenish-yellow and full of nectar.

An insect called the ivy bee needs these flowers to live. In late winter, the plant makes berries. These berries can be dark purple, black, or even yellow.

Birds like thrushes and woodpigeons eat the berries. This helps the plant spread its seeds to new places. Many bugs and small animals also find homes in the thick ivy.

Hedera is a genus of evergreen plants that includes 12 to 15 different species. These plants are woody and can either creep along the ground or climb upward. They belong to the family Araliaceae. Most species are native to regions like Western and Southern Europe, North Africa, and parts of Asia reaching as far as Japan and Taiwan. Because they stay green year-round, they are frequently used as ornamental plants to cover walls, fences, or tree stumps.

The way ivy grows changes significantly depending on its environment and age. On level ground, the plants remain low, typically only 5 to 20 cm in height. However, if they find a surface to climb, such as a tree or a rock face, they can reach at least 30 m above the ground.

The plant uses two distinct growth forms. Juvenile stems are slender and flexible. They use small aerial roots to attach themselves to a substrate like bark or stone. As the plant matures, it develops adult shoots. These shoots are thicker and self-supporting, meaning they do not require those small roots to stay upright.

Leaf shape also shifts as the plant moves from its juvenile stage to its adult stage. Juvenile leaves are palmately lobed, which means they have several points or lobes. When the plant reaches its adult stage and grows into sunny areas, it produces unlobed, cordate leaves. Cordate leaves are shaped like a heart. This transition occurs when the stems reach fertile flowering areas, usually at least 2 m above the ground.

These adult stems produce greenish-yellow flowers in clusters called umbels during the autumn or early winter.

Taxonomists categorize these species using several scientific details. One major way to group them is by the structure of their trichomes. Trichomes are tiny hairs found on the undersides of the leaves. Some species have scale-like trichomes, while others have stellate trichomes, which are star-shaped.

Species also vary in their chromosome numbers. While the basic diploid number is 48, some species are tetraploid with 96, hexaploid with 144, or even octaploid with 192 chromosomes. This genetic variety helps scientists understand how the different species are related.

The evolutionary history of Hedera suggests it originated in East Asia. The earliest known fossils of the genus were discovered in Korea and date back to the Oligocene epoch. From there, the genus expanded westward. It eventually reached Europe during the early-middle Miocene epoch.

Over time, many species have become allopatric, meaning they live in different geographic areas. Some species have even been known to hybridize. For example, a garden hybrid called × Fatshedera lizei was created in France in 1910 by crossing Fatsia japonica with Hedera hibernica.

Ivy plays a vital role in many ecosystems by providing food and shelter. The flowers are rich in nectar, which attracts many pollinators. The ivy bee, Colletes hederae, is completely dependent on these flowers for its entire life cycle.

In late winter or mid-spring, the plant produces berries that are greenish-black, dark purple, or sometimes yellow. These berries contain one to five seeds and are eaten by birds like thrushes and woodpigeons. As the birds eat the fruit, they disperse the seeds to new locations. Additionally, the dense, woody tangles of ivy provide nesting sites for birds and small mammals, as well as homes for many invertebrates.

While ivy is useful, it can also cause problems in certain environments. In North America, some ivy species are considered invasive exotic species. They can grow very quickly through underground rhizomes and above-ground runners. This allows them to smother native vegetation in forests and woodlands.

In Europe, the impact on trees is usually minor, though heavy growth can sometimes lead to windthrow damage. However, in North America, aggressive ivy can overwhelm a tree's ability to perform photosynthesis or maintain structural strength. Finally, users should be aware that the berries are moderately toxic to humans, and the foliage contains substances like falcarinol, which can cause skin irritation.