What constitutes a bonsai (bone-sigh) tree is a very subjective topic, even within the bonsai community. To a beginner, anything in a bonsai pot is a bonsai. As they progress, most begin to realize that a bonsai tree is an evocative and believable representation of a tree we might find growing on a mountainside, meadow, or in any other natural setting, so their view of what constitutes 'bonsai' changes as the practitioner grows in the art. As someone who has judged bonsai shows I can say, if the tree doesn't evoke emotion or lend itself to a story, there is still a lot of work to do on the tree. Part of the work needed to improve an unimpressive tree is most often more refinement, which makes the tree appear older and more realistic - part of being evocative of a story. As bonsai practitioners evolve, some of them readily let go of the need to tell people their tree is really a liner (a liner is a very young tree, usually 1-3 years old and often sold in groups of 100 - 5,000 or more) in a pot. They understand and remember there was a time that a liner in a pot defined most of the trees in their collection, and how proud they were to be a member of the bonsai community and practicing the art of bonsai. Unfortunately, there are a few bonsai practitioners who are always ready to tell someone what is a 'bonsai to them' really isn't. That's unfortunate. I don't think people should ever be discouraged from trying their hand at any horticultural endeavor - especially when it comes to bonsai, which to me is ever-evolving art with a 4th dimension, that of life. The personal rewards and satisfaction it offers are unlimited; and for a lifetime, you can continue to grow in all the aspects that make up the art. The satisfaction of being on the journey is much more important than being the best, because the rewards that come from learning and trying, and the delight of achievements realized along the way accumulate and last forever. So personally, if the OP has a ponytail bonsai, I'm good with that, and I encourage her/him to learn all (s)he can about the plant and the art, because it's that knowledge that will move you forward. Al

Yes, it is Crepe Myrtle, as everyone has said. They love full sun, hot conditions and plentiful water. Make sure you specify that you want a tree, not a shrub, as some species are shrubs. The tree in your picture has obviously been pruned heavily. Some people like to do this. I personally love them left to grow as high as they like. The high flowers look lovely, as do the mottled trunks.

Anything besides the timing to indicate that particular cultivar? And not another of the many kinds of Japanese cherry? (Glen Cove should indicate the geographic area, as that will be pertinent).

the goo is gumosis ....a systemic problem that is not correctable ... and will lead to the trees demise ... which in tree time.. might be 5 or 10 years ... who knows ... https://duckduckgo.com/?q=gumosis&t=ffcm&ia=web the leaf issue reminds me of japanese beetles ... but you would have to find the bug for complete ID ... and it might be long gone.. since i see unaffected leaves ... where are you.. big city name ... isnt this a deciduous tree ... and it will soon be losing its leaves ... so who cares if they fall off ugly ... it is tree planting time for most of us.... perhaps its time to plant a new tree or two.. and plan on getting rid of this one due to the disease .... ken https://sites.google.com/site/tnarboretum/Home/planting-a-tree-or-shrub