Likening the word to a seed is very significant.  A seed has a root system, a leaf system, and a fruit or reproductive system within it and so does the word. 

The first system to grow is the root system.  Our roots must grow deep and strong to weather the storms that come our way.  If the root isn’t deep, the trials and struggles of life will dry up the root and we will fall away. 

Next we must have a leaf system.  The leaf system brings shade to the root to keep the ground moist.  The leaf system also brings shade to the birds and a good leaf system will attract others to come under the shade of the tree.  The leaf system also brings beauty to the tree and attracts others to it.  Thus, we must provide shade to the poor and needy.

Finally the seed has a fruit or reproductive system.  This system comes last and is there for the harvest, some thirty, some sixty, and some a hundredfold.  The fruit is there to feed the nations.  If the cares and concerns of the world and the lust of other things do not choke the tree, then fruit will come and we will be blessed and a blessing. 

In Mark chapter four, first the blade, then the ear, then the corn in the ear, and then the sickle to harvest the fruit.  In the Christian life we are born of an incorruptible seed which is the word of God.  That word like a seed must be planted deep within the soil of the heart to endure until it bears fruit.  Unless that seed, that word, is planted on good soil we will not produce a harvest and unless we produce a harvest the cycle of life is not complete.  God wants us to produce a harvest but we must weather the storms and conditions of life which try to destroy the tree of life that is planted within us as a seed.  The devil comes only to kill, and steal, and to destroy.  God comes that we might have life and life in abundance.