Proposition of a key to Equisetum genus

Resumen

The Equisetum L. genus is the only living representative of the Equisetace family which used to be very large. Only a dozen species have survived to this day. Unfortunately, the degree of knowledge of both the genus as a whole and individual species is insucient. In particular, the range of variability of their individual anatomical and morphological features is not accurately known. In addition, the occurrence of hybrids further impedes the correct determination of specimens. The result of this is a large amount of misleading determination even in renowned herbarium collections. The key presented is a proposal that will allow, perhaps, to avoid many such mistakes in the future.