Antibiosis

On a small, sparsely unnamed planet, Lieutenant Commander Elliss, on temporary assignment, discovers a peaceful farming village under the control of a telepathic organism that exhibits characteristics of both plants and animals. His mission, and the villagers, are threatened by these organisms.
His first encounter is shortly after landing when he is attacked by a hard-shelled pod that travels through the sand at his landing site. Avoiding the sand as best he can, he makes his way to where a group of villagers is engaged in farming chores. After introducing himself to the village leader, he discovers that all the villagers are infected by a similar red pod that has attached itself to the base of the skull of the villagers.
Elliss first suspects that there is an outside influence that controls the villagers. Unable to locate any such controller, he turns his attention to the villagers. Their behavior is controlled and highly irregular for farmers. A visit to his shuttle by the village leader later that night provides the clue he needs: the village leader had torn the pod from his neck and fills Elliss in on recent happenings.
In alliance with the village leader, Elliss plans to remove the pods from the villagers. In the course of this rescue, the villagers are turned against him by the collective telepathic power of the alien plants. Elliss is cut off from his shuttle and must work his way around to a side that borders a river.
Gaining entry to his shuttle, he is accidentally pinned against a wall with the hatch open. The pods attack but cannot find a foothold on the metal floors and are left floundering around as the village leader arrives to help Elliss escape. They flee to the wooded area where there is not enough sand for the pods to travel.
While trying to return to the shuttle the next day, they are attacked again and Elliss suffers a wound to his arm from a lucky hit. A barbed projection pierces his arm and releases a numbing venom. When he awakes, he forms a plan with the village leader to recover the village and destroy the pods. A discovery made while putting the plan together changes the final outcome: the pods are terrified of water but the plants from which they originate are critical to the environment. The solution must strike a balance between the villagers and the plants.