From the Super Mario Wiki
This article is about the item from Super Mario World 2: Yoshi's Island
, Super Mario RPG: Legend of the Seven Stars
, and Yoshi's Island DS
. For information about other uses of "Flower", see here
Flowers are plant items that appear in Super Mario Land, Super Mario World 2: Yoshi's Island, Yoshi's Island: Super Mario Advance 3, Super Mario RPG: Legend of the Seven Stars, and Yoshi's Island DS. In Super Mario Land, the Flower's first appearance, the Flower (also known as Superball Flower or simply Super Flower) morphs Mario into Superball Mario, granting him the ability to shoot Superballs. The Flower in this game is very much as the Fire Flower and appears identical to pre-Super Mario World Fire Flowers in-game.
from Yoshi's Island DS
In Super Mario World 2: Yoshi's Island and Yoshi's Island DS, there are five flowers in each level, and netting all five earns Yoshi an Extra Life and fifty points. Getting all flowers in each level is also necessary for Yoshi to get a perfect score. Collecting at least one flower is also necessary to access a Bonus Challenge via the GOAL! Ring, and the chance of playing a Bonus Challenge is increased by collecting more flowers. The flowers in this game appear as sleeping seeds if frozen or not collected at the end of a level.
from Super Mario RPG
In Super Mario RPG: Legend of the Seven Stars, a Flower automatically increases Mario's maximum FP (Flower Points) by one. Flower Points are needed to perform special attacks. These flowers resemble Fire Flowers from Super Mario Bros. They do not directly grant the ability to shoot fireballs, however, though some of Mario's flower-point-consuming special attacks involve shooting fireballs.