Greater celandine, or Chelidonium majus, is a perennial plant that is native to the Mediterranean region and parts of Europe. This member of the Papaveraceae family of flowering plants is a close relative of the poppy. It was brought in the 17th century to the United States, where it has become an invasive wildflower that grows with abandon through waste areas, fields and abandoned properties. The bright orange sap that oozes from this plant when any part of it is broken stains anything it touches and contains alkaloids that are extremely irritating to the skin.
Celandine is a fairly tall plant, reaching between 2 feet and 4 feet (61 cm to 1.2 m) in height. It has lobed leaves, simple four-petaled yellow flowers and tends to grow in large clusters. This plant is not fussy and will grow in either full sun or shade, in any type of soil. It flowers throughout summer and produces many long seedpods full of small black seeds. A single greater celandine plant can generate as much as a 0.25 pound (113 g) of seeds.
These herbaceous plants are often planted in informal wildflower gardens, where they often spread out of control and become a nuisance. They are considered an invasive weed in many areas. They have thick, fleshy roots that break easily, and they can be very difficult to eliminate once they have become established. Spreading can be discouraged if the dead flowers are cut before they go to seed, because greater celandine is an abundant seed producer and nearly every seed that is left behind will fall to the ground and germinate.
For those who wish to grow celandine as garden plants, it is easily done. Seeds can be planted directly into the ground, where they will germinate in two or three weeks and quickly grow into blooming plants. They are fairly hardy but require a thick layer of mulch in areas where winter temperatures are below freezing. Even with protection, these plants may not survive extremely cold temperatures. In most areas, however, they will thrive and spread, and frequent weeding will be required to keep them contained.
Greater celandine is considered toxic to humans and animals. In spite of this, it is considered a valuable herbal medicine when used with caution and under the supervision of a healthcare provider. It is used mostly as a tincture or tea to purge the body and remove toxins. It also has been employed as a treatment for gallbladder and liver diseases.