Grass and flowers generating above water and blocks that don't support them

I went into a jungle and found seeds on sand. This should be a generation issue with grass, since grass should not generate on sand. It fails, so some of them drops seeds instead. Another issue is that I found 2 block high flowers have only its top block shown when incorrectly generated on lakes. This is a rarer occasion, but when I broke the flower, it has the particules of a sunflower instead and dropped nothing.