Hi
I think as a family maybe gesneriads. Sinningia in particular will stay under two inches in dia. and bloom it;s head off lol. Certainly some of the tropical sundews.
though they tend to clump. Some of the tropical selaginells can be kept at almost any size. gary

Some sundews and most if not all butterworts are minis as are true mosses. Depends too on just what your definition of mini is. Some tillisandras are quite small as are some earthstars and some african violets.

I know you mentioned orchids, but I have to say, I just bought one for my tabletop terrarium and absolutely adore it. The orchid is a mounted gastrochilus.

Sarah

Forgot to mention Selaginellas. Also have a fern that I picked up last fall. Thus far it is behaving itself and retain miniature status (and stature)

Nice Gastro, Sarah. Is it G. japonicus?

Yes, it is. However, I don't know if it is the best for all terrariums, as I just discovered it was getting a bit too warm in there. Not good during heat waves, unless the AC is on 24hr/7days.

Sarah

I have used, Baby's Tears, Button Ferns, Maidenhair Fern, peperomia, Rex begonia, Fittonia & they all have done well. Hope this helps!

Any tropical bonsai plant, like Ficus benjamina "too little".
Nice selection at http://www.meehansminiatures.com/

Many small carnivorous plants do well, like Venus flytrap, sundew, small pitcher plants.

Mini begonias -- neat leaf textures.
http://www.belislesviolethouse.com/Begonias.html

Miniature creeping ficus (Ficus pumila Quercifolia) -- http://www.glasshouseworks.com/trop-f.html
http://www.belislesviolethouse.com/terrariumlist.html
(They also have lots of other great minis and micros, see the terrarium section)

Micro-mini Sinningias and African violets -- available at
http://lyndonlyon.com
http://www.davesviolets.com
http://www.belislesviolethouse.com/
sometimes sold on ebay

Miniature ferns (my favorites!):

Miniature Fluffy Ruffles Fern (Nephrolepsis exalta )
Available at http://www.lyndonlyon.com/CP%20List%20Terrarium%20plants%20NF.html
http://www.belislesviolethouse.com/terrariumlist.html
These are reasonably-priced, easy to propagate and share with friends.

Selaginella species
http://www.belislesviolethouse.com/terrariumlist.html
http://www.glasshouseworks.com

Logees.com has some neat mini-ferns, like Hemionitis arifolia and some Selaginella species.

You can find some really cool rare ferns, even rare miniatures, on ebay but it will cost quite a bit since bidding gets pretty competitive.

One of my favorite tiny ferns is Quercifilix zeylanica. Like 'Fluffy Ruffles' it stays very small. The little lower leaves look kind of like oak leaves, and are only 2-4" tall. It sends out taller ones occasionally which have a different shape and look interesting. I trim those off if it's growing in a very small bowl or jar. I don't remember if it has a common name.

Another really nice one is Lemmaphyllum microphyllum- "Japanese bean fern". It doesn't look like a fern at all, having small bright green, shiny leaves that creep around slowly on a tiny fuzzy vinelike rhizome. It's supposed to be an outdoor fern in cool climates, but it does fine in terrariums for me, staying smaller than the outdoor or greenhouse plants.

Another good looking and easily controllable tiny creeper is peperomia rotundifolia 'pilosior'. Little succulent round leaves with an interesting pattern on top of them.

If you get into gesneriads, there are many interesting miniature plants you can find through clubs and societies. Phinaea albolineata, P. multiflora 'Tracery'... xPhinastema 'California Dreaming' adds beautiful color. Many of these have dormant times.

Chirita tamiana is somewhat common now, and is almost always blooming.

Vincent