Jaconda

Jaconda was the home planet of the Jacondans and was once a verdant world overseen by Azmael.

Geographic features and life forms
Jaconda was the planet closest to its sun. Two smaller planets orbited further out. It was originally a lush planet with deep forest and an abundance of plant life until the Gastropods awoke. All of the trees were stripped of their foliage and all the nutrients were sucked out of the soil. (TV: The Twin Dilemma)

History
Jaconda was originally overseen by Azmael, a Time Lord friend of the Fourth Doctor. However, the Gastropods awoke and took over the planet using their telepathic abilities. They devoured all available plant life on the planet. The native Jacondans faced a famine.

The leader of the Gastropods, Mestor, commanded Azmael to find a way to move the two outer planets to orbit around Jaconda for food. Azmael kidnapped two geniuses from Earth, Romulus and Remus Sylvest, and brought them to Jaconda to work out the calculations for this task. He happened to meet the Sixth Doctor, who followed him to Jaconda and tried to help him with his problem. The Doctor eventually worked out that moving the two planets would send them into the sun and cause a massive solar burst which would destroy all of Jaconda, except the eggs of the Gastropods. Azmael realised his error and helped the Doctor stop Mestor, giving up his own life.

After Azmael's death, Lieutenant Hugo Lang stayed behind to help the Jacondans and was given Azmael's royal ring. (TV: The Twin Dilemma)