I have three Japanese maples and a cork bark oak bearing clusters of leaves, no runners. Grown from seed, 1994 and 2010, respectively. Several years now the leaves are growing tightly compacted, touching each other and close to existing branches and trunk with no new growth runners. What is happening? I have repotted them and found the roots rather lame and not what you would expect for the size and age of the trees. How can I overcome this situation?