plants, alpha, depth buffer

So I've used an alpha blend before with a depth mask (no depth writing). The problem is that if I am drawing a ton of plants, then I dont want a 0 alpha written to the depth buffer. Would I use a texgen or do I need a pixel shader? If you didnt understand, I have a huge tree right in front of the camera with lots of gaps where there are no leaves. I dont want to write anything to the depth buffer so that I don't have to sort all the branches of the tree.