It produces its fruit all the time with the Permission of its Lord, and Lord Allah presents parable for mankind so that they may remind others in their heart’s language.
The ‘Good word’ mentioned in verse is Adhikr. It is the Unbreakable Rope extended from the Paradise to earth as explained in verse 2: 256. It is Safeguard from all calamities, disasters, diseases, and Hellfire as explained in verse 5: 48. It is the Ticket for returning to the Paradise as told in verses 73: 19 and 76: 29. With Adhikr-the Bounty and Mercy- let mankind rejoice, that is better than whatever they are gathering as told in verse 10: 58. Adhikr is the Prosperity, there is no poverty with It and there is no prosperity without It as explained in verse 2: 272. It is the Balance and Trust to keep the universe in its equilibrium as told in verses 33: 72 and 57: 25. It is the Food, Cloth, and Sight of the human soul as explained in verse 7: 26. It is the Strongest Weapon to do Jihad against the hypocrites and terrorists. So, whoever holdfasts It, he did holdfast Lord and is guided into the Straightpath as explained in verses 3: 101-102.
The leaves of trees absorb carbon dioxide from the atmosphere, and excrete oxygen and water; thus, reduce air pollution due to carbon dioxide and thereby regulate atmospheric temperature. By absorbing the polluted water and fertilizers, the roots of plants help to maintain hygienic surroundings. The roots of plants also prevent soil erosion and help to maintain the fertility of the soil. The water vapors evaporated from the leaves cool the atmosphere and form the clouds which lead to rainfall. For all creatures both on land and water, oxygenated atmospheric air is crucial for maintaining a healthy life. That is why a believer who testifies Adhikr is compared to a good tree. Adhikr commands mankind endowed with intelligence to plant trees even though they realize that tomorrow is the Dooms Day. See explanation 2: 267; 3: 79-80 and 7: 58.