This lifeform is widespread in North America.

Smooth horsetail (Equisetum laevigatum) is found widely in North America. The white margins of the teeth on the sheath with the black girdle below help identify this species.

Horsetails are a class in the Fern Phylum (Class Articulate or Class Equisetinae) with a single order with a single family with a single genus of perhaps twenty-five species with almost worldwide distribution. Because the plants were used for rubbing and polishing, this group has been called the Scouring Rushes. The following eleven species are listed in Kartesz: (* indicates the species is pictured and discussed herein)

            *Equisetum arvense
            *Equisetum fluviatile
            *Equisetum hyemale
             Equisetum laevigatum
             Equisetum palustre
             Equisetum pratense
             Equisetum ramosissimum
             Equisetum scirpoides
            *Equisetum sylvaticum
             Equisetum telmateia
             Equisetum variegatum

Fern Phylum (Pteridophyta) is a large group of primarily tropical plants that typically reproduce by a complicated process involving spores. There are typically two different generations involved in the reproductive process.

Although Ferns have vascular tissue, they are separated from the seed plants in that ferns grow directly from the fertilized zygote. There are probably over 9,000 species in this group worldwide. In prehistoric times, this phylum was the predominant plant phylum on earth. Most of the coal and oil used for energy today derives from this phylum.

Although they are still numerous in moist areas, ferns have generally been replaced by seed plants. Most ferns are small to medium-sized plants. However, there are tree ferns in the tropics.

The Fern phylum is divided into several classes including:
horsetails - Class Articulate or Class Equisetinae
Club Mosses - Class Lycopodiinae
Psilotes - Psilotinae Class
Quillworts - Class Isoetinae
Ferns - Class Filicinae

The first four classes are very primitive when compared to the last or fern class. Some authors have suggested that the fern class is more closely related to the seed plants than the first four classes.

Kartesz finds 27 different families in the Pteridophyta. He finds 893 full species growing in greater North America, including Hawaii, Puerto Rico, the Virgin Islands, and Greenland.

Plant kingdom contains a large variety of different organisms including mosses, ferns, and seed plants. Most plants manufacture their energy from sunlight and water. Identification of many species is difficult in that most individual plants have characteristics that have variables based on soil moisture, soil chemistry, and sunlight.

Because of the difficulty in learning and identifying different plant groups, specialists have emerged that study only a limited group of plants. These specialists revise the taxonomy and give us detailed descriptions and ranges of the various species.  Their results are published in technical journals and written with highly specialized words that apply to a specific group.

On the other hand, there are the nature publishers. These people and companies undertake the challenging task of trying to provide easy to use pictures and descriptions to identify those species.