A very long time ago, someone at Garden Web asked for suggestions for a tall, narrow plant that would stay narrow, rather than spreading out and becoming vase-shaped with time. The reason was because the person had a fairly limited amount of floor space, and wanted the plant in an entryway, so any plants that got wide would eventually take up too much space and no longer be usable in that spot. I provided a number of suggestions in the thread, which for some reason has become a really reliable source of blog hits ever since. Which is kind of weird. I mean, I wouldn't have thought that many people have this problem.
So anyway. Here's a slightly expanded list of more or less upright, narrow, columnar plants that can be kept indoors. They're not all interchangeable -- you'd still need to be able to provide the right conditions as far as light, temperature, etc. And some of them do actually get a little wider with age. But the list below is at least a place to start, when looking for plants that will become tall but not take up a lot of floor space.
Suggestions are welcome, if readers can think of any other plants that fit the category.
Of these, my favorite three are probably Dracaena deremensis 'Janet Craig,' Euphorbia trigona, and Pachypodium lamerei.
Dracaena will generally be quite a bit wider than its pot, but it will tend to maintain that width for its entire life, getting maybe a little bit wider at the top with age. If cut back, they will resprout from multiple spots on the stem, making the plant a bit wider, but this takes a very long time to happen and isn't likely to be that big of a deal. They're very tolerant of low light, dry air, and other indoor conditions, but need occasional flushing of the soil with water, because they're somewhat mineral sensitive. They're also easily overwatered, so be sure to only water when the soil is very dry, and when you do water, water thoroughly. Too large of a pot can also cause them problems.
Euphorbia trigona is probably my favorite of the three: it needs very bright light and is easily overwatered, but it is otherwise very easy. As plants age, they will grow new shoots at the stems' corners, which will grow up as well, forming a tall narrow column of stems which is widest in the middle. They will generally need only as much floor space as the pot they're in. The sap is toxic, and may be dangerous to children or pets.
Pachypodium lamerei is of about average difficulty. Like the other two, it's easily overwatered, especially if injured. It needs very bright light and may go dormant during the winter, dropping its leaves and slowing water consumption (this isn't inevitable; my personal plant has never gone completely dormant, as far as I can tell, in the three winters I've had it). It's also more prone to spider mites than the other two, especially during the winter. Very old plants, or plants in very ideal conditions, will branch at the top, though this is not common in plants grown indoors year-round. Pachypodium is also both poisonous and covered in sharp, potentially harmful, spines.
I don't recommend against any of these plants especially, though I personally do poorly with Sansevieria trifasciata and don't intend to buy any more of them for that reason. I think most people have more trouble with Rhapis excelsa.
Cordyline fruticosa, unless cut back
Dizygotheca elegantissima, unless cut back
Dracaena fragrans 'Massangeana,' unless cut back
Dracaena marginata, some specimens, unless cut back
Dracaena reflexa 'Anita,' unless cut back
Dracaena reflexa 'Riki,' unless cut back -- is pretty wide to begin with, but doesn't get a lot wider
Euphorbia ammak, kinda (they will eventually branch on their own)
Euphorbia drupifera, kinda (they tend to lean with age, has been my experience)
Euphorbia grandicornis, more or less
Schefflera arboricola, some specimens, unless cut back
Yucca guatemalensis, unless cut back