btny.purdue/weedscience/

1. Botanical description • Field horsetail is a perennial with a spreading rhizome system. Like ferns, field horsetail does not produce flowers or seeds. This species reproduces by spores and more commonly by creeping rhizomes and tubers • Two separate stages in their life cycle. The one is the spore producing stage, which includes the vegetative stems. The other is called a gametophyte that goes through the sexual part of horsetail’s life cycle. The gametophyte requires a wet environment to survive • However, vegetative reproduction allows horsetail to wander into drier environments. Horsetail has a deep root system with rhizomes that can produce many terrestrial stems, giving it the appearance of a colony http://www.btny.purdue.edu/weedscience/

2. Botanical description • Plants produce two types of stems. The fertile (reproductive) stems appear in the early spring. The tips of fertile stems end in a yellowish to brownish spore-producing cone. Fertile stems wither and die once spores have been produced, usually by early summer • Sterile (vegetative) stems emerge later than the fertile stems and are markedly different. They look like miniature pine trees with their plume-like branches

3. Distribution both species, E. arvense and E. Hyemale, are ubiquitous in the US Map source: http://plants.usda.gov

4. Rhizome description • The rhizomes are dark brown or blackish, 3 to 5 mm in diameter and covered with brownish hairs that give them a felt-like feel; rhizome internodes are approximately 4 to 5 inches apart. Rhizomes grow vertically to 6 feet deep and horizontally to depths of 10 to 20 inches. The horizontal rhizomes branch freely, produce numerous shoots and form rounded tubers about 0.5 inch in diameter either singly or in pairs • Rhizome system produces numerous shoots and tubers. Tubers have a high starch concentration. Tubers and rhizomes are used both in vegetative reproduction and as storage organs. Illustration of vegetative growth of Equisetum arvense from tuber (a) and rhizome fragment (b) Sakamaki et al. J Plant Res (2006) 119:677–683 http://www.oardc.ohio-state.edu/weedguide/fullimage.asp?id=8

5. Rhizome description • Buds and tubers on the rhizomes are capable of reaching the surface from great depths. Single rhizome segments 0.5 inch long planted 6 inches deep easily produced new plants (Cloutier and Watson, 1985). Plants can only tolerate shade for short periods unless they have sizable quantities of carbohydrates stored in the established rhizomes. Tuber production drops rapidly as shade levels increase; conversely tuber production is optimized when plants grow in full sunlight. Horsetail responds to potassium and its growth is optimal in soils with high available K levels (Andersson and Ludegardh, 1999). • Horsetail rhizomes extend for long distances and are often 3 feet or more below the ground surface. Rhizomes send up numerous aboveground shoots of two different types at various times of the year. Tubers are primarily food storage organs but develop into new plants if removed from the rhizome. • Sterile shoots of horsetail (those that look like small pine trees) appear in early May and reach a maximum growth rate in July, maximum shoot height in August, and maximum shoot number in September (Marshall, 1985). Rhizome growth accelerates rapidly between June and July and peaks in October. Tubers appear in July and increase in weight until a killing frost occurs.