From Seed to Seed:
Plant Science for K-8 Educators

There are two types of cells within the plant body: reproductive cells and somatic cells.

Reproductive cells. A plant's reproductive cells, or sex cells, are the egg and the sperm. These are called gametes. Reproductive cells are formed when certain specialized cells in the plant body divide in a specific way, resulting in daughter cells. The daughter cells have chromosomes that occur singly, rather than in pairs. Cells in which the chromosomes occur singly are called haploid cells, abbreviated as n.

Somatic cells. Most of the cells in a plant are somatic cells. In fact, somatic cells (Gr. soma = body) can be defined as all plant cells that are not reproductive cells. Leaves, stems, and roots, for example, are made up of somatic cells.

In somatic cells, the chromosomes occur in pairs. In other words, the cells contain two sets of chromosomes. Why are there two sets? One set has been donated by one parent, the other set by the other parent. Cells that contain paired chromosomes are called diploid cells (Gr. di = two), abbreviated as 2n.

Let's take a step backwards and look at the creation of a plant.

Similar to animal life, a new plant life is created by the union of two haploid cells, the egg (n) and the sperm (n). The egg contains the chromosomes contributed by one parent and the sperm contains the chromosomes contributed by the other parent.

This union creates a zygote (2n) that develops into an embryo and, eventually, a plant. The simplified diagram to the left shows the result of that union, a diploid plant cell with two sets of chromosomes (2n = 4, n = 2).

The plant that results from the union of egg and sperm contains both sets of chromosomes in each of its cells.