Hypogeal, hypogean, hypogeic and hypogeous (lit. 'underground'; from Ancient Greek ὑπό (hupó) 'under' and γῆ (gê) 'earth')[1] are biological terms describing an organism's activity below the soil surface.
In botany, a seed is described as showing hypogeal germination when the cotyledons of the germinating seed remain non-photosynthetic, inside the seed shell, and below ground.[2] The converse, where the cotyledons expand, throw off the seed shell and become photosynthetic above the ground, is epigeal germination.
In water purification works, the hypogeal (or Schmutzdecke) layer is a biological film just below the surface of slow sand filters. It contains microorganisms that remove bacteria and trap contaminant particles.
The terms hypogean and hypogeic are used for fossorial (burrowing) and troglobitic (or stygobitic) cave-living organisms. The opposite terms are epigean and epigeic.
The term hypogeous is used for fungi with underground fruiting bodies - for example, truffles. The opposite term is epigeous.
References
[edit]- ^ "hypogeal". Merriam-Webster.com Dictionary. Merriam-Webster.
- ^ Adrian D. Bell; Alan Bryan (2008). Plant Form: An Illustrated Guide to Flowering Plant Morphology. Timber Press. p. 200. ISBN 978-0-88192-850-1.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction