Pachycauls are

plant Plants are the eukaryotes that form the Kingdom (biology), kingdom Plantae; they are predominantly Photosynthesis, photosynthetic. This means that they obtain their energy from sunlight, using chloroplasts derived from endosymbiosis with c ...

s with a disproportionately thick trunk, for their height, and relatively few branches. With certain pachycaul species, particularly the more

succulent In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...

varieties, they are commonly referred to as "caudiciformes", a reference to their trunk development of a moisture-filled

caudex A caudex (: caudices) of a plant is a stem, but the term is also used to mean a rootstock and particularly a basal stem structure from which new growth arises.pages 456 and 695 In the strict sense of the term, meaning a stem, "caudex" is most ...

for periods of

drought A drought is a period of drier-than-normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, ...

. By comparison, trees with thin twigs, such as oaks (''

Quercus An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

''), maples ('' Acer'') and ''

Eucalyptus ''Eucalyptus'' () is a genus of more than 700 species of flowering plants in the family Myrtaceae. Most species of ''Eucalyptus'' are trees, often Mallee (habit), mallees, and a few are shrubs. Along with several other genera in the tribe Eucalyp ...

'', are called leptocauls; those with moderately thick twigs, such as ''

Plumeria ''Plumeria'' (), also known as frangipani, is a genus of flowering plants in the subfamily Rauvolfioideae, of the family Apocynaceae. Most species are deciduous shrubs or small trees. The species are native to the Neotropical realm (in Mexico, ...

'', are called mesocauls. Pachycauls can be the product of exceptional

primary growth Primary growth in plants is growth that takes place from the tips of roots or shoots. It leads to lengthening of roots and stems and sets the stage for organ formation. It is distinguished from secondary growth that leads to widening. Plant growth ...

(as with

Arecaceae The Arecaceae () is a family (biology), family of perennial plant, perennial, flowering plants in the Monocotyledon, monocot order Arecales. Their growth form can be climbing palm, climbers, shrubs, tree-like and stemless plants, all commonly k ...

and

Cycadaceae ''Cycas'' is a genus of cycad, and the only genus in the family Cycadaceae with all other genera of cycad being divided between the Stangeriaceae and Zamiaceae families. '' Cycas circinalis'', a species endemic to India, was the first cycad speci ...

) or disproportionate

secondary growth In botany, secondary growth is the growth that results from cell division in the cambia or lateral meristems and that causes the stems and roots to thicken, while primary growth is growth that occurs as a result of cell division at the tips ...

, as with the baobabs (''

Adansonia ''Adansonia'' is a genus of medium-to-large deciduous trees known as baobabs ( or ). The eight species of ''Adansonia'' are native to Africa, Australia, and Madagascar but have also been introduced to other regions of the world, including Barb ...

''). The word is derived from the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

''pachy-'' (meaning "thick" or "stout") and the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

''caulis'' (meaning "stem"). All of the arboreal (treelike) species of

Cactaceae A cactus (: cacti, cactuses, or less commonly, cactus) is a member of the plant family Cactaceae (), a family of the order Caryophyllales comprising about 127 genera with some 1,750 known species. The word ''cactus'' derives, through Latin, ...

are pachycauls, as are most of the Arecaceae, Cycadaceae and ''

Pandanus ''Pandanus'' is a genus of monocots with about 578 accepted species. They are palm-like, dioecious trees and shrubs native to the Old World tropics and subtropics. Common names include pandan, screw palm and screw pine. The genus is classified ...

''. The most extreme pachycauls are the floodplains, or river-bottom, varieties of the African palmyra ('' Borassus aethiopum''), with

up to thick, and the Coquito palm ('' Jubaea chilensis''), with its primary growth measuring up to thick. The most pachycaulous cycad is '' Cycas thouarsii'' at up to diameter. The tallest pachycaul is the Andean wax palm ('' Ceroxylon quindiuense''), at heights of up to , and around in diameter. The most pachycaulous cactus are the barrel cacti (''

Echinocactus platyacanthus ''Echinocactus platyacanthus'' is a member of the cactus family Cactaceae. It is also known as the giant barrel cactus, golden barrel cactus, giant viznaga, or biznaga de dulce, and its Nahuatl (Aztec) name is ''huitzli nahual''.. It is native to ...

''), with primary growth up to diameter. The largest caudiciforme-type pachycaul is the African baobab (''

Adansonia digitata ''Adansonia digitata'', the African baobab, is the most widespread tree species of the genus ''Adansonia'', the baobabs, and is native to the African continent and the southern Arabian Peninsula (Yemen, Oman). These are long-lived pachycauls; rad ...

''); one specimen of which, called the Glencoe baobab (from Hoedspruit,

Limpopo Limpopo () is the northernmost Provinces of South Africa, province of South Africa. It is named after the Limpopo River, which forms the province's western and northern borders. The term Limpopo is derived from Rivombo (Livombo/Lebombo), a ...

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

) has a basal diameter (not girth) of . However, this particular tree has suffered a severe trauma and is dying. Pachycauls also differ greatly in their rates of growth, from the half-man tree ('' Pachypodium namaquanum'') which grows only each year to the palm '' Pigafetta elata'' which can grow or more in one year. Examples occur in these genera: *'' Pachycormus'' (

Anacardiaceae The Anacardiaceae, commonly known as the cashew family or sumac family, are a family of flowering plants, including about 83 genera with about 860 known species. Members of the Anacardiaceae bear fruits that are drupes and in some cases produce ...

) *'' Acanthocereus'' (

) *'' Peniocereus'' (Cactaceae) *'' Alluaudia'' ( Didiereaceae) *''

Adenium ''Adenium'' is a genus of flowering plants in the family Apocynaceae first described as a genus in 1819. It is native to Africa and the Arabian Peninsula. Cultivation and uses ''Adenium obesum'' is grown as a houseplant in temperate and tropic ...

'' (

Apocynaceae Apocynaceae (, from '' Apocynum'', Greek for "dog-away") is a family of flowering plants that includes trees, shrubs, herbs, stem succulents, and vines, commonly known as the dogbane family, because some taxa were used as dog poison. Notable mem ...

) *'' Crassula'' (

Crassulaceae The Crassulaceae (, from Latin ''crassus'', thick), also known as the crassulas, the stonecrops or the orpine family, are a diverse Family (biology), family of dicotyledon angiosperms primarily characterized by succulent leaves and a form of phot ...

) *''

Kalanchoe ''Kalanchoe'' ( ), (also called "kalanchöe" or "kalanchoë"), is a genus of about 125 species of tropical, succulent plants in the stonecrop family Crassulaceae, mainly native to Madagascar and tropical Africa. A ''Kalanchoe'' species was one ...

'' (Crassulaceae) *''

Beaucarnea ''Beaucarnea'' is a genus of flowering plants native plant, native to Mexico and Central America. In the APG III system, APG III classification system, it is placed in the family (biology), family Asparagaceae, subfamily Nolinoideae (formerly the ...

'' (

Asparagaceae Asparagaceae (), known as the asparagus family, is a family of flowering plants, placed in the order Asparagales of the monocots. The family name is based on the edible garden asparagus, '' Asparagus officinalis''. This family includes both ...

) *''

Pachypodium ''Pachypodium'' is a genus of succulent spine-bearing trees and shrubs, native to Madagascar and Africa. It belongs to the family Apocynaceae. Genus characteristics All ''Pachypodium'' are succulent plants that exhibit, to varying degrees, the ...

'' (Apocynaceae) *''

Dendrosenecio ''Dendrosenecio'' is a genus of flowering plants in the sunflower family. It is a segregate of ''Senecio'', in which it forms the subgenus ''Dendrosenecio''. Its members, the giant groundsels, are native to the higher-altitude zones of ten mou ...

'' (

Asteraceae Asteraceae () is a large family (biology), family of flowering plants that consists of over 32,000 known species in over 1,900 genera within the Order (biology), order Asterales. The number of species in Asteraceae is rivaled only by the Orchi ...

) *''

Bursera ''Bursera'' is a genus with about 100 described species of flowering shrubs and trees varying in size up to high. It is the type genus for Burseraceae. The trees are native (often for many species endemic) to the Americas, from the southern Uni ...

'' (

Burseraceae The Burseraceae are a moderate-sized family of 17-19 genera and about 540 species of woody flowering plants. The actual numbers given in taxonomic sources differ according to taxonomic revision at the time of writing. The Burseraceae are also ...

) *'' Cyanea'' (

Campanulaceae The family Campanulaceae (also bellflower family), of the order Asterales, contains nearly 2400 species in 84 genera of herbaceous plants, shrubs, and rarely small trees, often with milky sap. Among them are several familiar garden plants bel ...

) *''

Lobelia ''Lobelia'' () is a genus of flowering plants in the family Campanulaceae comprising 415 species, with a subcosmopolitan distribution primarily in tropical to warm temperate regions of the world, a few species extending into cooler temperate r ...

'' (Campanulaceae) *'' Dendrosicyos'' (

Cucurbitaceae The Cucurbitaceae (), also called cucurbits or the gourd family, are a plant family (biology), family consisting of about 965 species in 101 genera.

) *''

Gerrardanthus ''Gerrardanthus'' is a genus of flowering plants native to tropical Africa and South Africa, first described by William Henry Harvey (1811–1866), and named in honor of William Tyrer Gerrard (died 1866 in Mahavelona, Madagascar), botanical co ...

'' (Cucurbitaceae) *'' Givotia'' (

Euphorbiaceae Euphorbiaceae (), the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of Euphorbia, the type genus of the family. Most spurges, such as ''Euphorbia paralias'', ar ...

) *'' Delonix'' (

Fabaceae Fabaceae () or Leguminosae,International Code of Nomen ...

) *''

Fouquieria ''Fouquieria'' is a genus of 11 species of desert Flowering plant, flowering plants, the sole genus in the Family (biology), family Fouquieriaceae. The genus is native to North America and includes the ocotillo (''Fouquieria splendens, F. splende ...

'' (

Fouquieriaceae ''Fouquieria'' is a genus of 11 species of desert flowering plants, the sole genus in the family Fouquieriaceae. The genus is native to North America and includes the ocotillo ('' F. splendens'') and the Boojum tree or cirio ('' F. columnaris''). ...

) *''

'' (Malvaceae;

subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zo ...

Bombacoideae Bombacoideae is a subfamily of the mallow family, Malvaceae. It contains herbaceous and woody plants. Their leaves are alternate, commonly palmately lobed, with small and caducous stipules. The flowers are hermaphroditic and actinomorphic; the c ...

) *''

Bombax ''Bombax'' is a genus of mainly tropical trees in the mallow family. They are native to western Africa, the Indian subcontinent The Indian subcontinent is a physiographic region of Asia below the Himalayas which projects into the Indian ...

'' (Malvaceae) *''

Brachychiton ''Brachychiton'' (kurrajong, bottletree) is a genus of 31 species of trees and large shrubs, native to Australia (the centre of diversity, with 30 species) and New Guinea (one species). Fossils from New South Wales and New Zealand are estimated ...

'' (Malvaceae) *'' Cavanillesia'' (Malvaceae) *''

Ceiba ''Ceiba'' is a genus of trees in the family Malvaceae, native to Tropics, tropical and Subtropics, subtropical areas of the Americas (from Mexico and the Caribbean to northern Argentina) and tropical West Africa. Some species can grow to tall ...

'' (Malvaceae) *''

Dorstenia ''Dorstenia'' is a genus within the mulberry family, Moraceae. Depending on the author, there are said to be 100 to 170 species within this genus, second only in number to the genus ''Ficus'' within Moraceae. ''Plants of the World Online'' curre ...

'' (

Moraceae Moraceae is a family of flowering plants comprising about 48 genera and over 1100 species, and is commonly known as the mulberry or fig family. Most are widespread in tropical and subtropical regions, less so in temperate climates; however, their ...

) *''

Stephania ''Stephania'' is a genus of flowering plants in the family Menispermaceae, native to eastern and southern Asia and Australia. They are herbaceous perennial vines, growing to around four metres tall, with a large tuber. The leaves are arranged sp ...

'' (

Menispermaceae Menispermaceae (botanical Latin: 'moonseed family' from Greek ''mene'' 'crescent moon' and ''sperma'' 'seed') is a family (biology), family of flowering plants. The alkaloid tubocurarine, a neuromuscular blocker and the active ingredient in the ...

) *''

Cyphostemma ''Cyphostemma'' is a flowering plant genus in the family (biology), family Vitaceae, with around 250 species distributed throughout the tropics and subtropics. These species are Caudex, caudiciform and used to belong to the genus ''Cissus''. The ...

'' (

Vitaceae The Vitaceae are a family of flowering plants, with 14 genera and around 910 known species, including common plants such as Vitis, grapevines (''Vitis'' spp.) and Parthenocissus quinquefolia, Virginia creeper (''Parthenocissus quinquefolia''). Th ...

References

Plant morphology Plant anatomy {{Plant-morphology-stub

See also

References