In most cases there is NOT decorative rock placed on top of bonsai soil. The soil most often used for bonsai contains small "rocks" of some kind, whether it be crushed granite, baked clay, coarse sand, etc. Akadama is a specific variety of clay/rock that is often used, so this could be what you're thinking of. Another possibility is that many discount store or mass produced bonsai are sold with small rocks/gravel this is actually glued on the soil surface to keep everything in place while they are being shipped. Usually the first advice you'll see given regarding such trees is to get rid the of that glued-on rock! It impedes water flow, impedes the soil from drying out between waterings, and also makes it very difficult to check the soil to see if water is needed.
Hope this helps!
Craig

Not that kind of rock or gravel. It is a rock that is placed next to the bonsai, as a decorative piece. Not the junk that mall-sai have to make it attractive to the unwary.

Just a single rock, with unusual or colorful shape, that will enhance the bonsai.

I know that I am not describing it right, so sorry.

Cheri

You're describing it perfectly...

unfortunately, I don't know the proper term.

Hoping someone has the answer,

Josh

Could it be "suiseki," perhaps?
Seems right. I learn something new every day...

Cheers!

Just because you see rocks stuck beside the cuttings called 'bonsai' in ... Wal-Mart or other such places does not mean that they belong there (unless a tree is deliberately planted ON the rock), or that they add anything at all to the look of the thing. Suiseki is the name for the art of rock 'planting', which really is about finding interesting rocks to arrange in a landscape of their own, on sand (usually), with no plants in the picture at all.

Lucy, I read that Suiseki often does use plants.
Then, of course, there's root-over-rock and complete rock-plantings (both of which you mention). An interesting, well-placed stone is supposed to increase the sense of "scale" to the planting. I also read that darker stones were once the norm, but that lighter-colored, so-called "natural" stones are gaining popularity (for good or ill).

Just so I'm understanding you correctly: there is *no* proper term for the solitary rock used in many bonsai presentations?

"Just because you see rocks stuck beside the cuttings called 'bonsai' in...Wal-Mart or other such places does not mean that they belong there [...], or that they add anything at all to the look of the thing."

I feel exactly the same way toward those little statues and figurines that people add to bonsai. I guess some decisions will inevitably come down to personal taste.

Cheers!

Josh

I'm personally not aware of a name for one rock, but it's quite possible there is one and hopefully someone will know it.

I've spent about an hour on google, how interesting!

Came up with several terms, fascinating reading....

SUISEKI, viewing stone, scholar rock. I am adding a link, check it out.

Cheri, who thanks everyone for the ingo

Here is a link that might be useful: history of Scholar's rocks and such