Cats are born with the ability to grow flowers
Daisy's being the most common

All Witherclan cats have poisonous flowers
But they can get a non poisonous flowers it is incredibly rare.

A cat is born with their magic, however they won't know what it is until they become an apprentice. Everyone's magic stages are different.

When an apprentice enters the first magic stage, many tiny sprouts will appear wherever their flowers will blossom. This can be on their back, tail, legs, face, etc

A cat can use their powers however they'd like, as long as it's acceptable and within their ability. They can create flowers, vines, herbal remedies.

When using their powers, their flower makes a recurring appearance, blossoming in whatever they create.

Every cat's abilities look different, even if they go by the same name. A Warrior might make vines to lift themself off the ground, while a Mender might make vines to create a bandage for a patient.

A cat's appearance can change when their flowers blossoms, but only subtly (eye color, markings, etc.)

Usually, a Leader will have flowers that glow when they use their magic.

Mutations
1. A non Witherclan cat is born with poisonous flowers

FloraClan gifted the clans with their magic so they can fight against the poisonous plants that overran their forest. But since they cannot control what flower a cat receives, there's a chance a cat might blossom with poisonous flowers. In cases like these, the cat is isolated from their clan immediately. They are not allowed to eat, share tongues, or communicate with their clan mates. The only cats they allowed to visit them at this time are the Leader and the Mender. The Mender's job is to check if the cat's flower is fatal and to monitor how it grows. If they're not fatal, they can rejoin the clan with some extra precautions in place. If the flower is fatal and is a risk to the cats and the forest, the cat has two options: have the flowers forcefully removed, or be banished from the forest. Having the flowers removed is a painful process, as the flowers are linked to their magic. Without magic, a cat is weak and defenseless. But they'll be allowed to rejoin the clan as long as the flowers don't grow back. If the cat chooses to keep their magic, they are sent out of the forest by a specialized patrol. Any sight of this cat's petals on their territory will have them scouted and in some instances killed.

2. A cat grows multiple flowers.
This mutation is relatively harmless, but rare nonetheless. A cat usually only has one type of signature flower, but a cat with this mutation can have multiple. These cats are regarded as special and beautiful by their clan.

3. A Witherclan cat recives a non poisonous flower
If this was to happen the clan either kill them or abandon them in the forest.