The Tear Grass was a long blade of dark-green grass.
The Tear Grass appearance was very unique, it actually has two blades of grass fitted together as if it was the head of a screwdriver.
Roland observed the Tear Grass carefully and upon a closer look, he realized that above each blade that was on the form of screw's head, there was actually a liquid-like substance stuck into it.
According to the author of the website he read earlier, this liquid-like substance was called the 'tear'. It was also the main reason why the Tear Grass could make people shed tears just by being around them.
Once the 'tear' was vaporized, it would create an effect like that of a tear gas used by the armed officials.
One or ten Tear Grass that constantly had their 'tears' vaporized doesn't actually affect their surroundings that much except in a close room where the vapors were sealed.
However, Tear Island was full of Tear Grass.