Whisperweed

Whisperweed is a key item that appears in a few Final Fantasy games, and it first appears in Final Fantasy IV. It is a plant that functions like a phone because it can transmit sounds over large distances. In most of its appearances, the Whisperweed appears to consist of four-petaled flowers in a vase.

Final Fantasy IV
In Final Fantasy IV, when the party finds Edward in Troia Castle, he gives them a Whisperweed.

Later, as the party tries to retrieve the Earth Crystal from the Dark Elf, it defeats them in battle. However, the Whisperweed saves the party as its power sends music from the harp that Edward is playing to upset the Dark Elf, therefore ruining his concentration and magnetic field, allowing the party to use their metallic equipment again and defeat the Dark Elf.

In releases prior to the 3D remake, the Whisperweed is a pair of harps named the Twin Harps (also formatted TwinHarps in the original Super Nintendo version). Their function is to allow characters to send a sound from one harp to another. This was only the case in English localizations, as the original Japanese versions still describe them as being plants.

Unlike the original version, the Whisperweed is depicted within the 3D remake itself. It consists of a vase containing seven flowers, five of which are pink and two are yellow. Japanese guidebooks for original versions of Final Fantasy IV have a grayscale artwork depicting the Whisperweed as a very large flower wrapped in what appears to be a tiny vase.

Final Fantasy V
In Final Fantasy V, Xezat gives a Whisperweed to Galuf when they enter the Barrier Tower. The party separates into two groups, who traverse the left and right sides of the Barrier Tower respectively. Meanwhile, Xezat hides in the Generator Room and uses his own Whisperweed to communicate to both groups.