i dont really try to smoke either, its been ages since ive smoked a seed, so i going to have to say stems, but if they are there i would say a seed. Either way i try not to smoke either, i usually just sift my weed once its dry through a handheld sifter and it powders it up pretty nice, and makes it possible to remove the stems and seeds.

so its better than a grinder cause it removes seeds and stems, and gets it just as powdery. Try it, you'll never use a grinder, or smoke stems or seeds again.