(Photograph = Tristerix aphyllus on Echinopsis chiloensis, Patricio-Novoa-Quezada)

Introduction

Cacti are sturdy plants. If not overly watered, and if protected while young, they have few natural enemies. However, at least one cactus has a mistletoe enemy.

The Details

Echinopsis chiloensis is a handsome, columnar cactus that grows to 20-ft or more. It is the predominant columnar cactus of Chile. Until recently, it was known as Trichocereus chiloensis.  E. chiloensis grows from the Provence Talca in the south of Chile down to the Elqui Valley in the Provence Coquimbo in the north. There are many variations, some are not so tall, and 3-ft tall plants of any clone usually bloom well. E. chiloensis is host to Tristerix aphyllus, an invasive and parasitic plant that grows within the tissue of the cactus.

T. aphyllus has no leaves and no chlorophyll. It obtains all of its food and water from the host plant. It never even grows above the surface of the host except to bloom. It has beautiful tubular orange flowers followed by pink-white fruit. T. aphyllus is enjoyed by birds who consume the fruit and spread the seeds.

T. aphyllus is more common on larger cacti. Also, T. aphyllus has a negative effect on cactus reproduction. The most heavily parasitized cacti produce the fewest flowers.

Additional Reading: Studies of Tristerix aphyllus Infecting Trichocereus chilensis