This one has to be seen to be believed. And I have seen a lot of small trees in my time.
51 little elms - Ulmus glabra - the tallest no more than 6 inches high. The entire planting is probably about 16 in /41 cm across, if that. This entry is from a Spanish bonsai artist.
51 boggles your mind? Go on, then - count 'em.