The only extant species of Division Sphenophyta are the horsetails. These plants typically grow only two to three feet tall, and have small leaves arranged in whorls around nodes on the stem. As in conifers, cones house the reproductive structures of horsetails; in some plants, the cones are highly compressed stems at the ends of aerial branches on the plant, while in other species, the reproductive shoots are separate from the vegetative shoots.

Horsetails have life cycles like those of ferns, with a dominant sporophyte generation (the plant). The cones, or stobili, contain multiple sporangiophores, consisting of a stalk with a flattened disc on the end. On the underside of each disk are 5-10 sporangia, which produce and release the haploid spores. When the spores germinate (only if conditions are right), they grow mitotically into the gametophytes; small, flattened, fragile green plants.

Each gametophyte has lobes that house the antheridia, which produce sperm, and the archegonia, which produce eggs. The egg is fertilized by the sperm in the archegonium, and diploid zygote begins to grow inside the archegonium. This matures into the sporophyte plant. A gametophyte is capable of supporting two or more sporophytes before dying. However, although many gametophytes germinate in nature, very few actually produce sporophytes. The horsetails rely primarily on vegetative reproduction (asexual) for survival.

Only one genus of the Division Sphenophyta survives today. Horsetails are primarily organisms of the past, dating back to the Devonian Period (409-363 million yrs. ago). They thrived during the Carboniferous Period, from 363 to 290 million yrs. ago, many as tall trees. The extant genus Equisetum, which may have lived during the Carboniferous period, is probably one of the oldest living genera of vascular plants. Today, the horsetails of the Carboniferous Period make up vast coal deposits, although the living species have little economic significance.