This page is devoted to the ancient fern group of Equisetum,
commonly called Horsetails (for other languages see here).
In case you don't know what I am talking about, here is a short introduction
(and you may find it usefull to view images
of some species):
The Horsetails are plants of a single living genus, Equisetum, and of the single family Equisetaceae of the single order Equisetales and the single classis Sphenopsida. This would be a good opportunity to take a look at the Tree of Life. These curious plants are the relicts of an ancient family known through fossils from as early as 325 million years ago, the geological period (Upper Carboniferous) when the remains of plants became the vast coal deposits that we use today.
Long-creeping, underground rhizome producing aerial stems at close intervals and forming a colony; aerial stems with hollow internodes, the size of the hollow and the arrangement of the different tissues and canals when seen in transverse section being diagnostic for the species; surface ridged longitudinally; silica deposited in the epidermis (in sometimes diagnostic patterns); stems appearing jointed, with leaves in whorls and reduced and fused into a sheath at the stem nodes, the number of leaves equals the number of stem ridges; branches absent or produced at the nodes; fertile stems emerging before sterile ones, similar or dissimilar to sterile stems, with an apical cone composed of whorls of hexagonal, peltate sporangiophores bearing sporangia; spores green, each with four hygroscopic strap-like structures called "elators".
The species of Equisetum are found growing in wet places, such as standing water of shallow ponds or ditches, marshy areas, wet meadows, and moist woods. E. avense and E. ramosissimum often give the appearance of growing in xeric conditions (railroad embankments, etc.), but even here its rhizome system can be found penetrating saturated soil.
According to Hauke (1963) there are 15 living species in this genus (and a number of hybrids):
I am looking for all types of informations on this
family, that is literature, pictures, herbarium specimens and cultivars.
I am espacially interested in the following species: E. giganteum, E.
myriochaetum, E. diffusum and E. bogotense.
Please send me an email if you have something from the above.