Any lens can be used for landscapes photography and it depends on your preferences. But when talking about landscapes, most people think of wide angle lens. Do you like wide-view landscapes or do you like more intimate landscapes? What kind of camera do you have? And what is your budget because there are a lot of option (Canon and third party).
In general, Canon 10-20 (for crop body), 17-40, 16-35 are pretty good wide angle lens.
The thinking is that if you need to "look around" to take in a view, then probably your camera would benefit from a wide angle lens so it can also take in the view.
The one nuance of wide angle lenses is that in addition to a wider angle of view, they also "stretch" the depth of the scene. Distant objects will seem much more distant. You can learn to use this to your advantage.
For an APS-C (crop-frame) camera the 17-55mm f/2.8 is a good landscape lens (although you'll rarely need f/2.8 outdoors). For a full-frame camera (5D, 6D, 1DX) I recommend the 24-105mm f/4L. It's commendably sharp, and distortion and aberration are well controlled for a lens with such a long zoom range.
A couple of people have recommended a wide-angle lens. A WA is certainly nice to have, but I find that I use mine mainly for photographing buildings in the city, where I can't get very far back. Get a WA if you can afford it, but make sure you have a really good mid-range walking around lens first. If you do get a WA, and you have a FF camera, you might consider Canon's new 16-35mm f/4L. I haven't used it, but so far it looks like a winner.
+1 with Robert's suggestions. Stick to standard focal length lenses, at least for the first good lens. Once you get the basics covered, then perhaps look at a wide angle.
Wide angle is nice, but it's frequently used to 'get it all in' for landscapes and all you get is a whole lot of forground with a bunch of buildings or landscape on the horizon. Makes for some very boring photos. WA is great for getting up close to a subject when you want the surroundings in the picture, or for tight spaces/big buildings. Even then, it can take some thought and processing to either minimize distortion, or make the distortion work for the photo.
Standard lens of the best quality that you can afford.
You'll need good depth-of-field.
Take overlapping shots with the camera held vertically
and stitch them together. Not too many and about 30 degrees overlap.
Best done on a tripod and ideally a mount to allow rotation
about the nodal point.
Try Googling "Landscape Photography."
"I recommend the 24-105mm f/4L." Right on! And it is an "L".
Best bang for the buck in the entire Canon line. You can find them brand new for around $700 bucks.
Not a great format on crop cameras. We don't know the first thing about the OP. Pushing a L lens, like it's the only choice duh, is comical. Thanks for the amusement.