tree
There's a plant called dill. That would be my first guess.
ice
Ephedra is a 7 letter medicinal plant that's used to treat allergies and asthma, but I don't know of a 6 letter plant.
hedge
MIMOSIA
The first two leaves on a plant are called cotyledons.
What is the first letter of a fourteen-letter word meaning a person in charge of a plant?
A Flower called "Narcissus".
Holly
The first root of a young plant is called the primaryroot.
The first bud in the embryo is called the apical meristem. It is a region of undifferentiated cells that give rise to various plant structures and tissues as the plant grows.
Python There is none because you are asking for a five-letter word and p, h, y, t, o, and n are six letters, not five! Phyto means plant.