Plants, trees and shrubs develop in numerous ways. Seeds are carried on the winds and settle in fertile soil, millions of natural perennials remain or die and renew themselves and even animal droppings contain seeds that take root and grow in a constant cycle. These are some of the natural ways the earth propagates and sustains itself.
Humans have always planted to feed themselves and farming technology has developed in ways that now feed billions of people. Individual or community gardeners grow food and flowers on a smaller scale and friends might trade plant cuttings to root and grow in their homes.
Our world cannot survive without plant propagation!