No discussion of Biblical plants should leave out the well-known tree that Zacchaeus climbed in Luke 19, the sycamore, also known as the Egyptian fig (Ficus sycomorus).

While fig fruit was obtained from this tree, it was primarily used for its timber because of it straight trunk and branches.

Sycamore tree 

A sycamore tree at Neot Kedumim Biblical Landscape Reserve.

The 19th century missionary in the Middle East, William Thomson, said of this tree: "This sycamore is a remarkable tree. It not only bears several crops of figs during the year, but these figs grow on short stems along the trunk and large branches, and not at the end of twigs, as in other fruit-bearing trees. The figs are small, and of agreenish-yellow color. At Gaza and Ashkelon I saw them of a purple tinge, and much larger than they are in this part of the country. They were carried to market in large quantities, and appeared to be more valued there than with us. Still, they are, at best, very insipid, and none but the poorer classes eat them. It is easily propagated, merely by planting a stout branch in the ground, and watering it until it has struck its roots into the soil. This it does with great rapidity and to a vast depth. It was with reference to this latter fact that our Lord selected it to illustrate the power of faith."

The 'shiqmah' (sycamore) was once abundant on the coastal plain and in the shephelah (foothills) as I Kings 10:27 states: "Solomon accumulated chariots and horses; he had fourteen hundred chariots and twelve thousand horses, which he kept in the chariot cities and also with him in Jerusalem. The king made silver as common in Jerusalem as stones, and cedar as plentiful as sycamore-fig trees in the shephelah." 

The shiqmah was grown as a crop tree, this is seen for example when Baal hanan was steward over David’s olive and sycamore trees (I Chronicles 27:28).

Amos was a dresser of the shiqmah as cited in Amos 7:14: "Then answered Amos, and said to Amaziah, I was no prophet, neither was I a prophet's son; but I was an herdsman, and a gatherer of shiqmah [sycamore] fruit."

Psalm 78: 46-47 recounts the destruction of such crop trees that existed in Egypt:
"He gave their crops to the grasshopper,
their produce to the locust.
He destroyed their vines with hail
and their shiqmah (sycamore) figs with sleet."

Isaiah the prophet said that even though the people of the nation of Israel were punished and their shiqmah trees were cut down, rather than repent they continued to hold on to their pride and self-confidence:
The Lord has sent a message against Jacob;
it will fall on Israel.
All the people will know it - 
Ephraim and the inhabitants of Samaria - 
who say with pride
and arrogance of heart,
The bricks have fallen down,
but we will rebuild with dressed stone;
the shiqmah [sycamore] trees have been felled,
but we will replace them with cedars [erezim].”
- Isaiah 9:8-10

This is an edited excerpt from Alvin Johnson's iBook 'Biblical Flora', 2017. The book is available for free download on iTunes. A teacher's edition is also available for purchase.