Aerial root
909402
216921062
2008-06-03T20:39:46Z
Persian Poet Gal
538346
Reverted edits by [[Special:Contributions/74.38.158.25|74.38.158.25]] ([[User talk:74.38.158.25|talk]]) to last version by Peripitus
''"Pneumatophore" redirects here. It is also a name for the air bladder of the [[Portuguese Man o' War]].''
[[Image:Pneumatophore overkill - grey mangrove.JPG|thumb|right|The Grey Mangrove (''[[Avicennia marina]]'')'s pneumatophore type aerial roots]]
[[Image:Schefflera bonsai 2.jpg|thumb|right|200px|A ''[[Schefflera arboricola]]'' [[indoor bonsai]] soon after branch pruning to show extensive aerial roots.]]
[[Image:Banyan tree Old Lee County Courthouse.jpg|thumbnail|right|200px|[[Banyan]] tree of undetermined species in [[Fort Myers, Florida]]]]
'''Aerial roots''' are [[root]]s that are aboveground. They are almost always [[adventitious]]. They are found in diverse plant species, including [[epiphytes]] also known as air plants, which includes the [[orchid]]s, tropical coastal swamp trees such as [[mangrove]]s, the resourceful [[banyan]] tree, the warm-temperate rainforest [[Metrosideros robusta|rātā]] and [[pōhutukawa]] trees of [[New Zealand]] and vines like [[English ivy]] and irritating [[Poison-ivy (plant)|poison ivy]].
==Types of aerial roots==
This plant organ that is found in so many diverse plant families has different specializations that suit the plant habitat. In general growth form, they can be technically classed as ''[[gravitropism|negatively gravitropic]]'' (grows up and away from the ground) or ''positively gravitropic'' (grows down toward the ground).
===Aerial roots as supports===
Non-parasitic [[ivy]] are vines that use their aerial roots to cling to host plants, rocks, or houses. Prop roots form on aerial stems and grow down into the soil to brace the plant, e.g. [[maize]] and [[screw pine]].
===Stranglers===
The [[Banyan]] tree (''[[Ficus]]'' sp.) is an example of a strangler fig that begins life as an [[epiphyte]] in the crown of another tree. Its roots grow down and around the stem of the host, their growth accelerating once the ground has been reached. Over time, the roots coalesce to form a pseudotrunk, eventually strangling and killing the host. Another strangler that begins life as an epiphyte is the [[Moreton Bay Fig]] {''Ficus macrophylla'') of tropical and subtropical eastern Australia, which has powerfully descending aerial roots. In the subtropical to warm-temperate rainforests of northern New Zealand, ''[[Metrosideros robusta]]'', the rātā tree, sends down aerial roots down several sides of the trunk of the host. From these descending roots, horizontal roots grow out to girdle the trunk and fuse with the descending roots. Eventually the host tree dies, leaving as its only trace a hollow core in the massive pseudotrunk of the rātā.
===Pneumatophores===
These specialized aerial roots enable plants to breathe air in habitats that have waterlogged [[soil]]. The roots may grow down from the stem, or up from typical roots. Some botanists classify these as ''aerating'' roots rather than ''aerial'' roots, if they come up from soil. The surface of these roots are covered with [[lenticel]]s which take up air into spongy tissue which in turn uses [[osmosis|osmotic]] pathways to spread oxygen throughout the plant as needed.
[[Avicennia germinans|Black mangrove]] is differentiated from other mangrove species by its pneumatophores.
''See also'' [[Cypress knee]]
===Haustorial roots===
These roots are found in [[parasitic plant]]s, where aerial roots become cemented to the host plant via a sticky attachment disc before intruding into the tissues of the host. [[Mistletoe]] is a good example of this.
===Propagative roots===
Horizontal, aboveground stems, termed [[stolon]]s or runners, usually develop plantlets with adventitious roots at their nodes, e.g. [[strawberry]] and [[Chlorophytum|spider plant]].
Some leaves develop adventitious buds, which then form adventitious roots, e.g. piggyback plant (''Tolmiea menziesii'') and mother-of-thousands (''[[Kalanchoe daigremontiana]]''). The adventitious plantlets then drop off the parent plant and develop as separate [[cloning|clone]]s of the parent.
==See also==
*[[Adventitious]]
*[[Root]]
*[[Vegetative reproduction]]
*[[Vine]]
==References==
# UCLA Botany glossary page: [http://www.botgard.ucla.edu/html/botanytextbooks/generalbotany/typesofroots/ Roots]
[[Category:Plant morphology]]
[[de:Luftwurzel]]
[[hu:Légzőgyökér]]
[[ja:呼吸根]]
[[simple:Aerial root]]