This odd little plant is the most common and weedy horsetail in Illinois. The cone-bearing fertile shoots resemble brown mushrooms (something like the morel mushroom), while the infertile shoots look like small conifers during the summer. Few people realize that both types of shoots are produced from the rhizomes of the same plant. Common Horsetail differs from other horsetails by its brown fertile shoots, which lack chlorophyll. Other Equisetum spp. (Horsetails) in Illinois produce green fertile shoots that are similar to infertile shoots in appearance. The whorled branchlets of Common Horsetail can become almost as long as the central stem – they are produced in great abundance and often obscure the central stem's visibility by the beginning of summer. Other Horsetails produce branchlets that are much shorter than their stems, or they produce no branchlets at all. There are other technical differences between Common Horsetail and other Horsetails, but it is usually easy to identify in the field.