When I picked up one of the flowers in a plains biome using middle-click, all block and decorative items textures turned black. Mobs and the player seem to be unaffected by this, though. When I opened the inventory (this is part of the glitch), all placeable blocks/ decorative items/ certain redstone items/ beacon have a completely black texture. This doesn't seem to affect battle items, food, materials, potions and the items in the tab the beacon is in, except the beacon of course.
Restarting Minecraft does not solve this.

I made a number of pictures to illustrate the problem, but my browser somehow refuses to upload images now. I'll upload them when I can.