Prunus

Many trees grow sweet fruit.

These trees grow plums and cherries. They also grow peaches and apricots. Some even grow almonds.

These fruits have a hard pit inside. The pit is like a small shell. It holds a seed.

You can eat the soft fruit. The hard pit is not for eating. Some seeds are safe to eat. Other seeds can make you sick.

People use these fruits in many ways. They make sweet jams. They also dry the fruit. Some people roast the seeds.

These trees have pretty flowers. The flowers are often pink or white. They can also be red.

The Prunus group is a large family of plants.

It includes many trees and shrubs. You might know them as plums, cherries, peaches, or apricots. It also includes almonds. There are about 340 different species in this group. These plants live in many places. They grow in North America and South America. They also grow in parts of Africa and Eurasia.

Most of these plants grow sweet fruit. The fruit is called a drupe. A drupe is a fleshy fruit with a hard center.

This hard center is called a stone or a pit. The pit is a shell that protects a seed. You can eat the soft part of the fruit. You cannot eat the hard pit. Some seeds are safe to eat, like sweet almonds. Other seeds can be poisonous.

People use these fruits in many ways. They make jam or dry the fruit. They also use seeds for roasting. Many people grow these plants for their pretty flowers. The flowers are often white or pink. Some can even be red.

Some trees may get a condition called gummosis. This is when gum leaks out of the bark. This happens if the tree has a wound.

The Prunus group is a large family of flowering trees and shrubs.

This group belongs to the Rosaceae family, which is the rose family. It includes many delicious foods we eat every day. You might recognize them as plums, cherries, peaches, or apricots. It also includes almonds, which are often used in snacks. There are about 340 different species in this group. These plants grow all over the world in many climates. They are native to North America and South America. They also grow in the temperate and tropical parts of Africa and Eurasia.

Most Prunus plants produce a special kind of fruit called a drupe.

A drupe is a fleshy fruit with a hard center. This hard center is called an endocarp, but many people call it a stone or a pit. The fleshy part on the outside is called the mesocarp, and this is the part we eat. The stone acts like a tough shell to protect the seed inside. This seed is called a kernel. In some species, like sweet almonds, the kernel is safe to eat. However, in many other species, like apricot kernels, the seed is actually poisonous.

Scientists have studied these plants for a very long time. Carl Linnaeus was a famous scientist who worked with these names in the 1700s. In 1737, he used four different names for these plants. By 1758, he simplified them into just two groups. Other experts, like Liberty Hyde Bailey, noticed that these plants change into one another very smoothly. This makes it hard to tell exactly where one species ends and another begins. Because they are so closely related, they are often grouped together in one large genus.

We can also look back at the history of these plants through fossils. The oldest confirmed Prunus fossils date back to the Eocene period. These fossils were found across the Northern Hemisphere. Some very old pieces of wood, seeds, and leaves were found in the Princeton Chert of British Columbia, Canada. These finds come from the Okanagan Highlands. These areas were home to many different plants about 52 million years ago. The fossils show that these plants have been evolving for a very long time.

You can find Prunus plants in your own neighborhood or grocery store. People grow them for their sweet fruit or their beautiful flowers. The flowers are often white or pink, and sometimes they are red. They can grow alone or in small groups on the branches. We use the fruit to make jam, canning, or even dried fruit. We also use some seeds for roasting. Sometimes, these trees face hard jobs like staying healthy. For example, some trees get gummosis, which is when gum leaks from the bark after a wound.

The genus *Prunus* is a diverse group of flowering trees and shrubs. It belongs to the Rosaceae family, which is commonly known as the rose family. This genus is very important because it includes many foods humans eat. These include plums, cherries, peaches, nectarines, apricots, and almonds. Collectively, these are often called stone fruit. There are approximately 340 accepted species within this genus.

Most *Prunus* plants produce a specific type of fruit called a drupe. A drupe is a fleshy fruit that contains a single hard shell. This fruit has several distinct layers. The fleshy outer part is called the mesocarp. This is the part that people usually eat. Inside the mesocarp is the endocarp, which is the hard shell. We often call this shell a "stone" or a "pit." The endocarp protects the seed, also known as the kernel, located inside. While some kernels are edible, such as sweet almonds, others are poisonous, like apricot kernels.

Scientists use different ways to classify these plants. Traditionally, researchers divided the genus into several subgenera based on physical traits. One famous system from 1940 by Alfred Rehder proposed six subgenera. These included *Amygdalus* for almonds and peaches, and *Cerasus* for true cherries. Other groups were *Prunus* for plums, *Padus* for bird cherries, and *Laurocerasus* for cherry laurels. *Lithocerasus* was also added to include bush cherries.

Modern science uses a different method called phylogenetic classification. This method looks at DNA and other sequences to see how plants are related. This newer research divides *Prunus* into three main subgenera. The first is *Subg. Padus*, which includes bird cherries and cherry laurels. The second is *Subg. Cerasus*, which contains true cherries like sweet and sour cherries. The third is *Subg. Prunus*. This large group contains many sections, including apricots, peaches, and various types of plums.

We can learn about the history of *Prunus* by looking at fossils. The oldest confirmed fossils of this genus date back to the Eocene epoch. These fossils have been found across the Northern Hemisphere. Some of the earliest specimens include wood, seeds, and leaves. These were found in the Princeton Chert of British Columbia, Canada. These fossils come from the Okanagan Highlands. This area was home to diverse forests about 52 million years ago.

Plants in the *Prunus* genus have many different physical features. Most species are either deciduous, meaning they lose leaves, or evergreen. Their leaves are usually simple and alternate. The flowers are often white, pink, or sometimes red. These flowers typically have five petals and five sepals. They can grow alone or in small groups called umbels or racemes.

Growing these plants can be difficult due to various pests and diseases. Some trees suffer from gummosis. This is a condition where gum leaks out of the bark. The tree produces this gum to respond to wounds from insects or disease. Another issue is black knot fungus, which is a major fungal disease in Northern America. Some species also face attacks from parasites like *Laetiporus gilbertsoni*. This is a brown rot parasite that affects decorative red-leaf plum trees on the Pacific coast.