Fragrance

Fragrance was a planet once visited by the Doctor, Ian, Susan and Barbara. It was within the solar system of Alpha Cygni, a sapphire blue sun.

Geography
Topographically, it was said to have hills of silver and valleys of gold, though it was not known whether this was a metallurgic or metaphoric description. Its trees were said to be red. Like Gallifrey, the trees of Fragrance had leaves of silver. The planet's water was said to be "like wine". Because its ocean was emerald it was probably, therefore, not strictly made of water. Nevertheless, the green liquid, whatever its chemical composition, was apparently vital to the nourishment of flowers, and existed in fountains, as well as the Emerald Sea.

The planet was rich in thorium, one of three vital elements to the safe operation of the Doctor's TARDIS. (BFA: The Fragile Yellow Arc of Fragrance)

Sapient life
Fragrance was inhabited by highly-advanced Near-Humans, whose society had evolved to a near-utopia. The planet's engineers and craftsmen made a device of durable crystal and thorium which would have helped the Doctor better control the TARDIS so as to return Ian and Barbara to their own time. At least some of the residents of Fragrance were of sufficient intelligence to be led into the TARDIS and to comprehend the basics of its operation when guided by the Doctor.

Some of the inhabitants encountered by the TARDIS crew included: Rhythm, Rhyme, Iamb, Melody and Harmony. (BFA: The Fragile Yellow Arc of Fragrance)