Groups of plants are called GUILDS

When you put plants together that will reduce your labor and your need for fertilizer and intervention, this group of plants in Permaculture and in Food Forest gardening is called a Guild.
By placing plants in a guild to fill all the available niches, such as the needs for nitrogen, carbon, mulch, insect attraction and repellant, wildlife habitat, water saving techniques and wind control, as well as meeting all the other needs of the plants in the grouping, you are forming a Guild.
Guilds of plants have been around forever, native americans planted Guilds called 3 sisters which was corn, squash and beans. The beans fed the corn, grew up the corn and the squash mulched the area and brought up nutrients from deep in the soil, etc.
Guilds create landscapes that work more like nature, or forests, and create beautiful and productive habitats for the plants, the wildlife and the humans that tend them.

You should design each garden guilds with the best possible plant to meet the needs of the other plants in the guild. One example of complicted guild design is the Walnut tree guild. I have several walnut trees on my property and walnuts exude a compound from their roots called Juglone, it is a poison to many other plants and will prevent many plants from growing near them. This is where it is necessary to do your homework when planting walnuts, or planting near existing walnuts. There are some plants that tolerate Juglone and some that thrive with walnuts, but many just can't grown near them. An example is the Apple tree, it will not grow within 25 to 50 feet of a walnut tree. I also have a lot of apple trees on my property so it is good to know that they don't grow well near each other. However, a peach tree will tolerate Juglone so you can grow a peach or a cherry tree under a walnut tree.

It is important to know your plants and their needs to enable  your plants to form healthy communities that will eventually take care of each other providing food, mulch, wind protection, wildlife attraction and repellance and shelter, and any other need for the particular guild.

Guilds are generally based on function such as pollinator attractor, healthy soil, nutrient accumulator, mulch plant, erosion control, wind control, toxic soil cleanup, etc.

Most North American field guide will list plant communities that are lists of plants that grow together in certain areas of the country, if you are from another country you'll have to seek out that information in your area. Later I will list a few of the North American field guide communities that might be in your areas.

Also when  you walk around your area or even drive, you may find indications of natural guilds, such as the fact that you see a black currant bush growing beneath a maple tree. The currant is enjoying the shade of the maple.

As I said in another post, one of the most important thing you can do on your property is to plant pollinator attracting plants, like these spring flowering bushes and trees. They will keep your bees and birds happy and keep them on your property.

This Pear tree is in a guild with comfrey, daylillies and aegopodium growing beneath it. The comfrey makes a mulch and brings up nutrients from far deep in the soil and the bees love it, the daylillies form a mat that attracts more bees and other insects for pollination of the pears. The aegopodium is an edible ground cover that is a spreading mat that has fall flowers that also feed the bees.

Another thing that happens in this particular guild is that when the pears come off the tree, they drop on the soft leaves below and don't get bruised and damaged in the harvest.

Remember, that a fruit or shade or nut tree just plopped down in your lawn is very unlikely to do well, and it will do so much better if planted in a guild. Later we will talk about superguilds.