The first thing that come to mind with Calendula to me, is “The Importance of Plant Names”
Too often plants are called by their common names, and in the world of herbs, this may cause some problems and confusion. Calendulas and Marigolds are a prime example.
While Calendula (Calendula officinalis) is an edible flower and medicinal herb; Marigold (Tagetes patula, also T. erecta and T. minuta) is a companion plant to vegetables and not so much edible or medicinal.
The problem is that both have lovely yellow or orange flowers, and both are confusingly commonly known as Marigolds, and both are sought after by vegetable and herb gardeners.
Calendula is often referred to as Pot marigold while the Tagetes are French Marigold, African Marigold and Inca Marigold.
The best advice to give when you are using flowers for food, and plants for medicine – BE SURE YOU HAVE THE RIGHT PLANT by checking its LATIN BOTANICAL NAME.
Quick identification guide – Tagetes have pinnate (feathery) leaves while Calendula have paddle-shaped leaves. The flowers are also different, with Calendula having daisy-like flowers with smooth petals and Tagetes’ petals thicker and shorter forming a pom-pom shape. The seeds of Calendula are curved (looking like tiny worms) and those of Tagetes are long, dark and thin.