Phylum Sphenophyta

Phylum Sphenophyta - Phylum Sphenophyta: Horsetails

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Phylum Sphenophyta: Horsetails Only one herbaceous genus—  Equisetum —of 15 species remains of this once large group of woody  trees of Carboniferous Age forests.  Equisetum  is one of the easiest plants to recognize: It has  jointed, ribbed and hollow stems impregnated with so much silica that a rasping noise is heard when  stems are rubbed together. Another of its common names, “scouring rush”, indicates one of the early  settlers' uses of the plants. At each stem node there is a ring of small leaves fused in a sheath.  Some species additionally have a whorl of branches at each node, which gives rise to the “horsetail”  common name. The aerial shoots arise from an extensive rhizome system.  Equisetum  sperm—like  those of the rest of the ferns and fern allies—require an external film of water in which to reach the  eggs;  Equisetum  is most often found in sites that are moist for at least part of the growing season. 
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This note was uploaded on 11/14/2011 for the course BIO 1421 taught by Professor Farr during the Fall '08 term at Texas State.

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