I have a render, it’s at the bottom.
Why are they there? My texture is seamless. I experience this a lot when I map it using Cube mapping.
You may want to UV map the texture instead. Or try to texture the bulb and stem separately and then tweak the texture coordinates so the textures match.
UV map? Like LSCM? How would I do that?
By reading the manual? 
But yes, to get a seamless texture you need a seamless unwrap first…but usually you will have a seam somewhere unless you use 3D (procedural) textures…
In this case a cylindrical mapping might do the trick already though…but pobably leaves an ugly “pole” at the top end.
Is this seamful because Blender just doesn’t have as good as mapping as it should, or what?
you cannot map a sphear to a plane without seems. Its mathmaticaly imposable. There are tricks and things you can do to reduce the effect… but there is just know way to do it. Note that hand tweking a UV unwarp texture is not the same thing.
delt0r
You know maps of the world?
You know how the continents are all destorted compared to how they are on a globe?
That’s the problem you’re having.
What you could do is use a 3d texture. Just contact someone from the 4th dimension, they use them all the time.