A meristem is a small cluster or layer of cells which are capable of dividing to produce all other cell types. The divisions of the meristem cells produce additional cells, called daughter cells. The kind of daughter cells each meristem produces depends on its location in the plant. The daughter cells can develop into leaf, stem, scape, root, or other cells.
Meristems are unique because their cells always remain small, soft, and capable of dividing for as long as the meristem persists. The daughter cells usually divide a few times too. Eventually the daughter cells enlarge and develop thick cell walls. Then they usually can’t divide again. The enlarging of the daughter cells as they expand produces the growth that we see.
A meristem is often called a “growing point” by garden writers. Think of “point” as a location in the plant, not as a “pointed place”. There are meristems in numerous locations in daylily plants. Knowing where meristems are and what they do helps to understand how daylilies grow.
It’s important to understand that meristems can behave differently. The shoot tip meristem produces parts that grow upward, such as the leaves and scapes. The leaves and scapes actually grow taller by meristems that are located at the base where they meet the crown. This causes them to “push up” from the bottom as they grow. The root meristem produces growth at the tip of the root. A root grows outward from the tip, reaching further into the soil.
The importance of meristems can be shown in how they produce new daylily plants and more flowers. Meristems can produce new daylily plants in several ways. A meristem in a crown can produce new fans. A meristem can produce a rhizome which grows a new fan at a distance from the parent plant. A meristem at a node on a scape can produce a proliferation, essentially a new fan. A meristem in a crown can be treated to convert a diploid shoot meristem into a tetraploid meristem which grows into a tetraploid plant.
Meristems produce all the daylily flowers, beginning with the flower stem (scape) which grows from the crown. Meristems produce all the flower buds on a scape. Meristems produce all the branches on a scape. In some daylilies a meristem at the tip of a scape can continue to grow and produce new buds (see bud-building).
