Occasionally an offshoot rises above ground far from the source plant against all odds. Trees in the desert spread shallow roots far and wide to collect as much moisture as possible since rain is sparse. What little falls doesn't soak in deep and must be absorbed quickly. Occasionally water will collect in a spot and one of the shallow roots takes advantage of it to sprout an offshoot.
Tenaciously the offshoots survive by drawing water from the main tree that has a deep taproot far into the earth as a reserve. The sprig then grows strong enough to build its own root system and become an independent thriving tree larger or smaller than the mother tree depending on location. The will to survive and grow makes the ultimate size irrelevant rather what matters is the ability to make maximum use of what is available and continue to live and grow.