(top) Why are the stackings of primordia (for example leaves) so regular, and centric, on a flat or curved surface? But in the astonishing anomaly here, shown by a plant in precisely my own backyard, the stacking was sequential on a line instead of winding around an axis on a surface! Except for this stem, the rest of the plant was developed in the normal way.
(bottom, left) This sunflower shows three flowers where one was expected.
(right, photo by Hans van Well) One of the rose's sepals developed like a twig.