Seedlings or emerging safely

Seeds are an excellent vehicle for allowing the growth of new plants. Many methods of dispersal; a couple of examples include seeds carried by wind or those dispersed by birds after they have eaten the berry, enabling the producer of the seeds in one location to have offspring in a wide geographical range.

One of the many problems seeds face in their journey is that of the initial stage of growing. Many obstacles, for instances rocks or heavy soil, may get in the way of the seedling as begins it's great adventure upwards into the world. 

The main stem of a plant is called the shoot apical meristem, in the beginning stages damage to the shoot apical meristem would mean death to the plant.

So how does a seedling protect itself?

In monocot seedlings, such as grasses, the coleoptile acts as a sheath-like covering to protect the shoot apical meristem.

In dicots; those plants that have two cotyledons, or embryonic leaves, the stem grows in a hook like formation with the cotyledons protecting the shoot apical meristem. as you can see in the photos below, the seedling is showing the hook like formation and the when it is clear of the soil it opens up the embryonic leaves.

Shortly after opening up the embryonic leaves, the shoot apical meristem begins to grow.

Then the first set of true leaves begin to grow and the plant much better placed to survive.

The roots also have an apical meristem, but it protects itself in a different way from the rocks, dirt and pathogens that it will encounter throughout its life. It is protected by a root cap. 

The cells of the root cap produce a mucilage to ease the way as the roots grow and are continually sloughed or shed, as they are destroyed, to be replaced by new root cap cells.

(Updated and reblogged from 24/01/2013)