Radek Walkowiak

Unido: 14.feb.2019 Última actividad: 24.sep.2020

Scientific Member, Program Manager and Botanist at The International Equisetological Association (IEA), World Equisetum Program, Research Service .. Passionate about plant biology, specifically in plant systematics, phylogenetic taxonomy of Equisetum, Equisetaceae, Tortula muralis complex, Marchantia polymorpha complex, botanical nomenclature and history of botanical explorations and discovery, conservation biology, in vitro plant breeding ..


“Equisetum is the single surviving genus of a class of ancient vascular plants that dates back to the mid-Devonian period (350 + million years ago). Species (no hybrids): 15 (18), nearly worldwide. Plants with jointed stems and distinct nodes. Leaves small, fused into sheaths, tips remaining free, toothlike. Sporangia borne on peltate sporophylls aggregated in cones. Spores green, rather white in hybrids. Gametophytes green, terrestrial, unisexual, male gametophytes smaller than female” ..

It is believed that the genus Equisetum developed in the Tertiary, arising from the much older genus Equisetites, originating in the Paleozoic era - Permian or Carboniferous. The Triassic species Equisetites arenaceus was initially included in the genus Equisetum. Some fossil species of the genus Equisetites resemble modern horsetails so much that the generic distinction between Equisetum and Equisetites was questioned and it was suggested that Equisetum may be considered the oldest modern vascular plant” ..

“According to phylogenetic analyzes carried out by Jean-Michel Guillon, the most basal representative of the genus is Equisetum bogotense. Incorporating it in the Equisetum subgenus not including the Hippochaete subgenus makes this subgenus a paraphyletic taxa” ..

“Equisetaceae [Michx. ex DC.] The only modern representative is the genus Equisetum [L.] Fossil plants of this family are usually classified as Morphotaxon Equisetites. These include morphologically diverse plants known from different continents, found mainly in Triassic and younger rocks, rarely already Carboniferous” ..

“The first Equisetum-Equisetites species appeared in the upper Devon about 375 million years ago. The genus Equisetum can therefore be called living fossils” ..

“Equisetales [DC. ex Bercht. & J. Presl] Four families, of which only Equisetaceae have modern representatives. These plants occur on Earth from the Devonian, but played a special role in the Carboniferous vegetation. Plants of various sizes, from small herbaceous plants to extinct calamites reaching about 20 (30) m high. The following taxa are distinguished: Calamitaceae (+Asterocalamitaceae), Equisetaceae, Tchernoviaceae, Gondwanostachyaceae (Formerly: +Phyllothecaceae, +Schizoneuraceae). Fossil taxa with an unclear taxonomic position: Annularia, Schizoneura, Neocalamites, Spaciinodum” ..

“Equisetopsida [C. Agardh] The class is fossil, living representatives are classified in one genus - Equisetum. Taxonomy: Equisetidae [(Warm.) / Engl. & Gilg], Equisetales [(Dumort.) / DC. ex Bercht. & J. Presl], Equisetineae [Rabenh.], Equisetaceae [Michx. ex DC.], Equisetum [L.] /// Hyeniales, Hyeniaceae /// Sphenophyllales [Seward], Sphenophyllaceae, Cheirostrobaceae /// Calamitales, Calamitaceae [Unger]” ..

“Equisetophyta [D. H. Scott / B. Boivin] The group is fossil, living representatives are classified in one genus - Equisetum. Taxonomy: Equisetophytina [Reveal], Equisetopsida [C. Agardh]” ..

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“Horsetails, Equisetophyta emerged from one trunk of Trimerophytes, Trimerophyta” ..
/ Radosław Janusz Walkowiak, 2008

“Trimerophyta is a cluster of fossil plants, very old terrestrial vascular plants that lived from early to middle Devonian. This group is paraphyletic; that is, it does not include all the descendants of a common ancestor. Trimerophytes were characterized by leafless shoots dividing pseudomonopodially, dichotomously or trichotomously, but one branch was more developed than the other, forming a sort of principal axis. The dichotomous branches shortened as they moved away from the main axis, creating tufted sporangia at the ends of only the side branches. Conductive bundles in trimerophytes were thicker than in rhyniophytes. Trimerophytes reached 1 m in height. Large trimerophytes were among the largest plants of the early Devonian. Trimerophytes descended from the oldest terrestrial plants - rhyniophytes, and gave rise to the extinct Cladoxylophyta, Psilotopsida, Polypodiopsida, Equisetopsida and extinct Progymnospermophyta. Classification of this group, orders: Pertica, Psilophyton, Trimerophyton, Dawsonites” ..


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