Aerial root

Aerial root

"Pneumatophore" redirects here. It is also a name for the air bladder of the Portuguese Man o' War."

Aerial roots are roots 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 orchids, tropical coastal swamp trees such as mangroves, the resourceful banyan tree, the warm-temperate rainforest rātā and pōhutukawa trees of New Zealand and vines like English ivy and irritating 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 "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.


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.


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 lenticels which take up air into spongy tissue which in turn uses osmotic pathways to spread oxygen throughout the plant as needed.

Black mangrove is differentiated from other mangrove species by its pneumatophores.

"See also" Cypress knee

Haustorial roots

These roots are found in parasitic plants, 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 stolons or runners, usually develop plantlets with adventitious roots at their nodes, e.g. strawberry and 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 clones of the parent.

ee also

*Vegetative reproduction


# UCLA Botany glossary page: [ Roots]

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Look at other dictionaries:

  • aerial root — noun : any root exposed to the air; especially : one of the roots found in epiphytes and climbers not in contact with the soil but usually anchoring the plant to its support and often functioning in photosynthesis compare prop root; see root… …   Useful english dictionary

  • aerial root — UK / US noun [countable] Word forms aerial root : singular aerial root plural aerial roots biology a root that grows down from a plant part that is above the ground …   English dictionary

  • aerial root — noun Any adventitious root that grows from a plant stem above ground …   Wiktionary

  • aerial root — n. adventitious root growing from the stem above ground level …   English contemporary dictionary

  • root —   1. Of plant. A a, mole, weli;    ♦ root with many sprouts, kumulau;    ♦ root of koali vine, kalēhuna.    ♦ Aerial root, ma alewa, a a lewalewa, a a kiolea, mahulukū; ule hala, uleule hala (of pandanus).    ♦ Root system, pa i a a.    ♦ Root… …   English-Hawaiian dictionary

  • root sheath — noun 1. a. : a many layered epidermal sheath surrounding an aerial root (as the velamen in an epiphytic orchid) b. : coleorhiza 2. : the epidermal lining of a hair follicle comprising two principal layers of cells that make up an inner and an… …   Useful english dictionary

  • Root-knot nematode — Larva of root knot nematode, Meloidogyne incognita, magnified 500×, shown here penetrating a tomato root Scientific classification Kingdom …   Wikipedia

  • Aerial roots — Root Root, n. [Icel. r[=o]t (for vr[=o]t); akin to E. wort, and perhaps to root to turn up the earth. See {Wort}.] 1. (Bot.) (a) The underground portion of a plant, whether a true root or a tuber, a bulb or rootstock, as in the potato, the onion …   The Collaborative International Dictionary of English

  • Root — This article is about the part of a plant. For other uses, see Root (disambiguation). Primary and secondary roots in a cotton plant In vascular plants, the root is the organ of a plant that typically lies below the surface of the soil. This is… …   Wikipedia

  • root — root1 rootlike, adj. /rooht, root/, n. 1. a part of the body of a plant that develops, typically, from the radicle and grows downward into the soil, anchoring the plant and absorbing nutriment and moisture. 2. a similar organ developed from some… …   Universalium