It was going to be undersea fantasy, but I decided not.
1) If you have tall grass, it’s not easy to see a long distance.
Obvious, of course, but many fantasy parties seem to lose and find each other without trouble all over the fantasy world, grasslands included. The long grass will make it harder and not easier, though. It may provide shelter from the enemies who are pursuing them, but it will also mean that they lose sight of each other fairly easily. The grass can actually be like fog, in that the party members are just a few feet from each other or from shelter but never know it.
Horses can help your characters see over the grass, but they themselves will take up the burden of forcing their way through. If they’re not used to such terrain, or if it’s rained and the ground is covered with mud as well as grass, they will be extremely tired by the end of a day’s riding, and need extra rest and care.
2) Grasslands are prey to the wind.
Without mountains, forests, or hills to stop it, wind storms over the plains at a much faster rate. A fantasy character caught out in the wind can’t bow his head or gulp in a few breaths of still air to escape it. It will keep sweeping along in spite of him, and stands a good chance of toppling the hero, especially on wet or unsteady ground. If the hero is leading a horse loaded with packs, or if he’s carrying something that tends to flutter and catch the air, the wind could tear the goods away and send them careening into the distance.
3) Rain and snow are also irritants.
Rain causes the unsteady ground previously mentioned, as well as swelling any rivers the grasslands may have and increasing the tendency of calm rivers to become raging torrents. Grass, unless piled firmly or made into an actual house, also doesn’t provide much shelter from rain, so your heroes will be left crouching helplessly in the open and cursing their fate. They may have to do so, however; driving rain that flies sideways at some points isn’t conducive to travel. Your characters won’t be able to see far ahead or stand the lash of it long enough to make any progress.
Snow is worse again. It can pick up to be a blizzard easily, given the wind and the lack of obstacles to stop the snow from flying. Travel in a blizzard on the plains is impossible. (No, I don’t care about your hero with superhuman strength; he’d still be blinded and unable to see if he was about to tumble into a hole or a river). When the wind stops blowing, then the heroes will have to deal with the problem of snow piled in drifts several feet high. Humans and horses can break through that, but only with a lot of puffing and blowing, by which time the exhausted horse won’t be much good to the heroes. (See also: northlands rant).
4) Herd animals are dangerous.
Some fantasy authors apparently regret the loss of buffalo, so make their plains rich with them- or wild cattle, or wild horses, or deer of some kind. Then the characters get to chase them on horses or admire them as they thunder majestically by.
Caught in the way of a herd, however, the characters will die. The animals are unlikely to see them in time, especially if they’re lying flat, and while some will go around or jump them, others won’t be able to. (If the herd is big enough, sheer pressure might keep any of them from going around or jumping). Dying with your head split open from a wild bull’s hooves is hardly the glamorous way to go. The faint hope that the herd will divide around your characters like a river around a rock and make them look dramatic and cool is hardly worth it.
5) Trees are likely to be small and scrubby.
Sometimes (translation: far too often) fantasy authors plant a grove of trees, or a whole forest, in the middle of the plains for no apparent reason. Unless you have actually worked out a magical explanation for this, it is Not To Be So. The sweep of the wind will make most trees twisted, small, and scrubby, not the magnificent oaks that most fantasy authors feel are the only “proper” trees for a forest.
Besides, without that magical explanation, how did the trees get there in the first place? Why did they take root and grow only so much, then no more? Why not become a forest, if the soil was that fertile, or why not stay plains, if the soil and the wind are that hostile to intruders?
6) Plains can be very, very dry.
This isn’t always the case, but places like the pampas of South America are hot and unpleasant. Water is rare, and the lack of shelter from the sun makes it dangerous to travel too much by daylight. The grass, if tall enough, can also cause people to lose each other easily, and can shelter predators that they would see from a distance in open country. If it’s an African/Indian setting, tigers can sneak up on your characters in peace and comfort while they’re playing “Marco Polo” with each other in an effort to get back together again. And in a drier environment, the tigers are more likely to be hungry.
7) The plains landscape itself can vary.
There can be canyons carved by the rivers, ravines, burrows underground, shallow caves, and small hills. It would probably be very difficult to catch criminals who knew the plains well, with all the ravines and caves they had to hide in (not to mention that pesky problem of hiding in the tall grass and not being easily visible even from horses). Similarly, intruders who ride up onto hills to get a look around are excellent targets for the arrows of hiding archers.
If the grass is short enough not to hinder vision, it can still prove a problem for horses. The grass is likely long enough to hide gopher holes, prairie dog holes, small abrupt drops, and so on. A horse can break a leg on ground that looks perfectly clear and level.
8) All that openness affects impressions of the sky.
The sun can seem overwhelming, and so can the moon and stars. Since most fantasy worlds don’t have cities with lights enough to blot out the sky, particularly in plains, the characters will notice the heavenly lights easily. If they come from less open country or from our own world, noting their reactions to this is a good idea.
9) Try to avoid making your plains cultures Native American stereotypes.
Again, as with desert cultures and their resemblance to Muslims, some similarities will be inevitable. Your people probably do hunt large plains animals (though not by lying down in their path). They probably ride horses. They probably ambush strangers by hiding in grass.
However, there’s no need to make them clones in values and religion and culture. Vary your fantasy a little, for the gods’ sake.
Well, that felt abbreviated. A lot of it’s obvious, though.