Top lane Zyra?
Does she work in the top lane?
It's true that she's very squishy and can easily die to assassins, but I personally think there are three major reasons why she may work very well in the top lane.
First, she has INSANE zoning power and harass. Think of Heimerdinger top, except with more reliable burst and damage. If a melee champion comes over to CS, you WWE or WWQ on top of them and they will lose a big chunk of their damage.
Second, she can place plants at bushes around the top lane to protect herself from ganks.
Third, she may have low health, but she can be built tanky. Most Zyra players build both Liandries and Rylais as her core items and by the time you have them you can kill them before they have an opportunity to kill you.