I had one plant foxtail in my first grow. She was an unknown strain that started very indica like (short with large fan leaves) then grew to 5 feet (isn’t that sativa like?) One of her tallest colas foxtailed the most so I think it was light/heat stress. We also may have let her go too long but she never showed amber trichomes. She did, however, hermie and now I know that foxtailing is a warning 
The foxtailing came at the end and the buds didn’t end up being light/airy… I thought it looked cool
