A geoxyle is a plant in which an enlarged, woody structure occurs beneath the surface of the ground. Such plants have developed independently in various plant lineages, mostly evolving in the Pliocene and subsequently diverging within the last two million years. In contrast to their close relatives, these plants have developed in areas with both high rainfall and a high frequency of fires. They are sometimes known as underground trees, and the areas where they grow as underground forests. The geoxylic growth forms of woody

subshrub A subshrub (Latin ''suffrutex'') or dwarf shrub is a short shrub, and is a woody plant. Prostrate shrub is a related term. "Subshrub" is often used interchangeably with "bush".Jackson, Benjamin, Daydon; A Glossary of Botanic Terms with their Der ...

s is characterised by massive lignotubers or underground woody axes from which emerge aerial shoots which may be ephemeral. These growth forms are found in savannahs in southern Africa. It is thought they developed in tandem with the spread of savannahs which resulted in an increase in tall grasses which are easily flammable during the long dry season associated with the savannah climate. Some well-known examples of geoxyles are the sand apple (''

Parinari capensis ''Parinari capensis'', the sand apple, is a species of flowering plant in the family Chrysobalanaceae, found in Botswana, DRC, Mozambique, Namibia, South Africa, Tanzania and Zimbabwe. It is tall. The leaves are elliptic with a white underside. ...

''), the plough-breaker (''

Erythrina zeyheri ''Erythrina zeyheri'', commonly known as the ploughbreaker, is a deciduous, geoxylic subshrub and member of the Fabaceae, which is endemic to southern Africa. It grows no more than 60 cm tall and occurs naturally in the higher altitude gr ...

''), the red wings ('' Combretum platypetalum'') and the wild grape ('' Lannea edulis''). Others are ''

Ancylobothrys petersiana ''Ancylobothrys petersiana'' grows as a climbing shrub up to tall. Its fragrant flowers feature a creamy or white corolla. Fruit is spherical, up to in diameter. Vernacular names include "climbing wild apricot". Habitat is woodland and rocky h ...

'', '' Diospyros galpinii'', ''

Elephantorrhiza elephantina ''Elephantorrhiza elephantina'', commonly known as the eland's wattle or elephant's root, is a subshrub in the mimosoid clade of legumes. They occur widely and in several bioregions of southern Africa. Considerable size variation has been noted, ...

'', ''

Eugenia albanensis ''Eugenia'' is a genus of flowering plants in the myrtle family Myrtaceae. It has a worldwide, although highly uneven, distribution in tropical and subtropical regions. The bulk of the approximately 1,100 species occur in the New World tropics, ...

'', ''

Eugenia capensis ''Eugenia capensis'', the dune myrtle, is a species of plant in the family Myrtaceae Myrtaceae, the myrtle family, is a family of dicotyledonous plants placed within the order Myrtales. Myrtle, pōhutukawa, bay rum tree, clove, guava, a ...

'', ''

Maytenus nemorosa ''Gymnosporia nemorosa'' is a spiny, somewhat sprawling evergreen shrub or small tree with drooping branches growing to some 5 m tall and found along forest edges in Mpumalanga, Eswatini, KwaZulu-Natal south to the Garden Route in the Southern Ca ...

'', ''

Pachystigma venosum ''Pachystigma'' was a genus of flowering plants in the family Rubiaceae but is no longer recognized. In 2005, it was sunk into synonymy with '' Vangueria'', based on a phylogenetic study of DNA sequence DNA sequencing is the process of dete ...

'' and ''

Salacia kraussii In ancient Roman mythology, Salacia ( , ) was the female divinity of the sea, worshipped as the goddess of salt water who presided over the depths of the ocean. Neptune was her consort. That Salacia was the consort of Neptune is implied by Varr ...

''.

References

{{reflist Forest ecology Plant life-forms