Everything on our planet including People, Rocks and Plants are made from the same elements of Fire, Earth, Air and Water. Each Element has a particular quality like heat with Fire or grounded-ness with Earth. Additionally each Planet/celestial body in our galaxy also holds a particular quality like fire with Mars or water with the Moon.
In Ayurveda, Native American, Yorubic and Chinese medicine, the quality of each Plant/Herb is associated with a Planet/Celestial body and Element. When we choose to work with a a plant, we can then create a state of resonance with a planetary or elemental energy of our choice to strengthen our counter-balance our energetic fields.
Add to this the Planetary configuration of your own natal birthchart with the current planetary dance and the results is ancient wisdom that connects us to nature and the universe. Planets and Elements are one of the many properties of a plant that was documented in the Doctrine of Signatures in the Middle Ages (but used by many Indigenous groups way before the 5th century).
Just an additional insight into how to work with plants. Please note the same plant might be classified in different (or overlap) signatures based on the herbalist or school of thought. Here are the qualities of each Planet/Celestial body:
Sun: Plants beneficial to the heart and circulation, heart shaped leaves are used for heart ailments, with yellow flowers that turn towards the sun.
Mars: Plants growing under adversity with thorns or prickles are identified with Mars symbolizing a pioneer, combative spirit.
Venus: Herbs that calm overindulgence in food and have lots of mucilage soothe irritated mucus membranes, associated with Taurus, ruled by Venus. Plants with beautiful flowers (Vervain, Violet) or red fruits (Raspberry) are also linked with Venus, the planet symbolizing beauty.
Saturn: Plants that are grounding and help one complete projects on the material plane. Perennials with long lives and plants with annual rings or woody plants are also identified with Saturn, the planet of aging.
Mercury: Plants that are good for the nervous system with hairy, fuzzy leaves often correspond to the cilia of the mucus membranes of the lungs, the body part associated with Gemini, ruled by Mercury. Plants that have finely divided leaves like the bronchi of lungs or vines that grow on trees are also associated with the planet of communication and ruling the nervous system.
Moon: Plants that may affect the subconscious, living by the water with little white or pale yellow flowers and juicy leaves or moon shaped leaves.
Jupiter: Herbs that promote a positive frame of mind and expansion. Large edible plants that remind people of the planet of expansion.
Neptune: Mystical herbs that are helpful in dream work or help bring physical concepts to the next plane. Plants growing in or near the ocean as Neptune is the Lord of the Oceans.
Uranus: Herbs that are hybrids and easy to transplant as Uranus is the planet of sudden changes. Herbs that energize, stimulate and promote inspiration.
Pluto: Herbs beneficial for enhancing sexuality and for balancing the physical and spiritual aspects of a personality.
And here are the qualities of each Element:
Air: Thought, mental power, communication, travel, intellect, abstract thinking, teaching, divination, freedom, happiness, laughter and beginnings.
Fire: Action, the will, passion, sex, lust , anger, desire, energy, work, purification , destruction, strength and protection.
Water: Emotions, dreams, compassion, love, sadness, psychism, healing, rest, cleansing, dissolution, astral travel and death/rebirth.
Earth: Stability, prosperity, food, money , wealth, crops,animals, home, mountains, strength, grounding, protection, nature and death/rebirth.