Equisetum hyemale L., 1753
|Common Names:||Horsetail, Scouring Rush|
The rhizome is underground, giving rise to numerous roots and shoots at the nodes. The aerial stems are about 1 m tall and 0.8 cm diameter, dark green, unbranched, cylindrical, jointed, hollow and with longitudinal ridges. The surface is covered with silica, thus giving the stem the rough texture. The tiny, teeth-like leaves are found at the joints, forming a sheath round the stem. The brown, cone-shaped strobili are developed at the ends of fertile branches which are shorter than the sterile stems. The sporangia are borne at the back of stalked sporangiophores. The spores are round and green, each with 4 elaters. The elaters are hygroscopic, thus changing in shape in response to the moisture in the air. This in turn helps in spore dispersal.
Native to Eurasia and Pacific North America, the plant has spread to many tropical and subtropical countries.
Singapore Botanic Gardens.
This is an ancient plant dominant in the latter part of the Paleozoic Era (360-250 million years ago) where there were many species and genera, some tree-like in size.
The spores germinate into green and lobed gametophytes that are anchored to the soil by numerous rhizoids growing from the under surface. Sex organs developed from these gametophytes that in turn produce sporophytes after the eggs are fertilised. For an account of the life history of a typical fern, see Pyrrosia piloselloides.
The rough stems have been used as sandpaper and to scour pots. Boiled and dried, the plant is used in Japan as a traditional polishing material. Some Plateau Indian tribes have been known to boil the plant and drink the water as a diuretic and to treat venereal diseases. In traditional Chinese medicine the stems are used to retard bleeding; increase the flow of urine; induces sweating during fever; and treat dizziness, dysentery, piles and "cloudy eyes." Equisetum hyemale makes an attractive plant in marsh gardens and fish ponds.
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