I have heard a very interesting tree fact about Redwoods. These trees grow in a family unit. In doing some research I came upon the the term: "Fairy Rings" or family circles, are likely all clones of the exact same tree, some additional questions:
Former botanist here.
It is not uncommon for this sort of behaviour to happen in the botanical world. There are many forms of this sort of thing, the most commonly seen one is coppicing. Coppicing is often done by people, but it also occurs naturally. In the natural case, an old tree (or a young one) falls over and each branch starts to grow upwards, putting down roots at the node with the parent trunk. Eventually the parent trunk dies and rots away, leaving an stand of trees that are all genetically identical, usually in an elongated ring around the shape of the trunk. Some of this form of growth is a result of the shape of the original tree and the rest is a result of competition for things like light.
There are also some species of tree like the Quaking Aspen (Populus tremuloides) which grows in vast genetically identical groves. In this case the species propagates through its roots.
To exactly answer your questions:
Coast Redwoods don't often reproduce from seed. Instead, they sprout from a (live) stump or from the base, trunk, or roots near the trunk of a living tree.
And yes, this commonly causes a "fairy" ring of trees to grow around the base of a mama-tree stump.
And then of course the same thing can occur for trees in that ring. And on and on. You don't notice this neat recursive pattern because some trees in a ring don't "make it", while others do, and as it's happening all over the place the result, except for single fairy rings, is obscured.
All such trees are genetically clones - same genes. And they join at the roots (and sometimes at the trunks). (And they share more, by way of shared mycorrhizal fungi.)
In some ways, such a group of clones could be thought of as a single individual.
Why do they have so many tiny cones with so many seeds, if they don't use them? They use them after a fire or a flood. (Stumps can also sprout then, if not completely killed.)
These critters are nearly impervious to fungi, insects, fire, floods,... A felled redwood tree trunk can lie on the ground hundreds of years without rotting. Then another tree falls across that one. And on and on, over the centuries... And bushes and trees (including redwoods, related or not) grow on top of felled trees. The "floor" of a primeval redwood forest can be lumpy, with deep "holes". You might think you're walking on the ground (whatever that might be) when you're walking along tree trunks.
Strange beasts. Almost like filter-feeders in the sea, their leaves (sprays of needles) are fine feathery filters that grab the cold Pacific-blown fog like a sponge. It's really about fog as much as it's about rain.
