Producers: Hazel Stark & Joe Horn Host: Hazel Stark Field horsetail, known by botanists as Equisetum arvense, shares a rough resemblance to a young pine tree—green in color overall and somewhat like a bottle brush in shape. These ancient plants are easy to notice now as they are just starting to emerge from wet fields and ditches. Photos, a full transcript, references, contact information, and more available at thenatureofphenology.wordpress.com.