![]() |
![]() Equisetum |
[EQUISETUM] Horse-tails
![]()
Horsetails are primitive vascular plants descended from huge trees which lived in the Paleozoic era (600-375 million years ago) and were the product of the Carboniferous period (270 million years ago). Coal seams were derived from them. Botanically they lie between the Ferns and the Clubmosses.
The Horsetails are split into two differing types: The other type of common horsetails (and their hybrids) have cone-bearing photosynthetic shoots where the cones are again at the summit but this time on a stem which bears leaves as well. These are green. Horsetails have a high silica content which once made them useful for polishing metal and wood.
Some Horsetails are poisonous, such as Horsetails unusually have a great many chromosomes, 2n=216 (meaning they have 216 different chromosomnes, repeated twice over - many more than humans where 2n=23 who (normally) have but 23 different chromosomes, repeated twice over. The 2n being the ploidy number, in this case diploid. Tetraploids are 4n, Hexaploids 6n, Octaploids 8n. Those with an odd number of sets, such as 3n, Triploid, are usually sterile and cannot produce seed because the chromosomes cannot totally pair up during duplication.
Horsetails have long been recognised as a plant which hyperaccumulates Silicon (in the form of polysilicates). It provides then with structural rigidity and is also found on the surface where it can impart a roughness to the stem (depending upon which species of Horsetail). Field Horsetail can hyperaccumulate silica by up to 20% to 32% by dry weight! Average Si 35g/kg (dry weight) with September being the month with highest concentration (in Slovakia)]. No doubt other Horsetails can do even better than this - for instance your Author wonders if Horsetails are also hyperaccumulators of zinc amassing up to 7000ppm of it.
|
![]() |
There are no species without hybrids, all hybridize. Moreover, hybrids are frequent. |
Great Horsetail. (Equisetum telmateia) | Photo: © RWD |
Field Horsetail (Equisetum arvense) | Photo: © RWD |
Wirral Horsetail (Equisetum meridionale) | Photo: © RWD |
Marsh Horsetail (Equisetum palustre) | Photo: © RWD |
Rough Horsetail (Equisetum hyemale) | Photo: © RWD |
Wood Horsetail (Equisetum sylvatica) | Photo: © RWD |
Water Horsetail (Equisetum fluviatile) | Photo: © RWD |
Variegated Horsetail (Equisetum variegatum) | Photo: (CC by 2.0) Geoff Toone |
![]() |