I have two, meristem and monocotyledon.
Meristems are the areas where growth happens with production of new cells. Also called a "growing point". Daylilies have several meristems. There's the apical meristem on top of the crown and from which the fan grows. Unlike many other plants, in daylilies and similar plants the apical meristem doesn't elevate as the plant grows but remains on the crown. So daylily leaves grow from the base not the tip. The root meristems are at the root tips, however. There are other meristematic areas, such as a type of "thickening meristem" that goes across the top of the crown if I'm understanding what I've read correctly, but that's getting too technical for me.
Some of the differences in meristem areas are because daylilies are monocotyledons (monocots) rather than dicotyledons (dicots). Something like a quarter of all flowering plants are monocots (meaning one cotyledon or "seed leaf"). The monocots are further divided into related groups called "Orders". Daylilies are in the order Asparagales and so are most closely related (disregarding other members of the daylily family) to plants such as onions, hyacinths, irises, and orchids. They are not closely related to grasses, as is sometimes said, that relationship is distant.
