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pachycaul

{{Short description|Plants with thick trunks and few branches}}

File:Boojum Tree.jpg

Pachycauls are plants with a disproportionately thick trunk, for their height, and relatively few branches.{{cite book |url=https://books.google.com/books?id=TXmOcFArNDkC&q=pachycaul |title=Concepts' Dictionary Of Agricultural Sciences |first=I. C. |last=Gupta |author2=S. K. Gupta |publisher=Concept Publishing Company |year=1992 |isbn=978-81-7022-301-6 |page=348}} With certain pachycaul species, particularly the more succulent varieties, they are commonly referred to as "caudiciformes", a reference to their trunk development of a moisture-filled caudex for periods of drought.

By comparison, trees with thin twigs, such as oaks (Quercus), maples (Acer) and Eucalyptus, are called leptocauls; those with moderately thick twigs, such as Plumeria, are called mesocauls. Pachycauls can be the product of exceptional primary growth (as with Arecaceae and Cycadaceae) or disproportionate secondary growth, as with the baobabs (Adansonia). The word is derived from the Greek pachy- (meaning "thick" or "stout") and the Latin caulis (meaning "stem").{{cite book|author=Stearn, W.T.|year=1992|title=Botanical Latin: History, grammar, syntax, terminology and vocabulary, Fourth edition|publisher=David and Charles}}

All of the arboreal (treelike) species of Cactaceae are pachycauls, as are most of the Arecaceae, Cycadaceae and Pandanus. The most extreme pachycauls are the floodplains, or river-bottom, varieties of the African palmyra (Borassus aethiopum), with primary growth up to {{cvt|2.1|m}} thick,{{cite book| last= Von Mueller | first= Ferdinand | date= 1881 | title= Select Extra-tropical Plants | location= Sydney | publisher= Government Printer | page= 50}}{{cite book | last= Carder | first= Dr. Al | date= 2005 | title= Giant Trees of Western America and the World. | location= Madeira Park, British Columbia | publisher= Harbour Pub. Co. Ltd. | page= 130}} and the Coquito palm (Jubaea chilensis), with its primary growth measuring up to {{cvt|1.8|m}} thick.{{cite journal| last= anonymous| date= January 1957 | title= | journal= Principes | volume= 1 | issue= 2 | page= 57}}{{cite journal | last= Caradine | first= Chris | date= November 1998 | title= A Day at Ocoa |journal= The Palm Journal | volume= [no volumes] | issue= 143 | page=20 with photo}}Riverside (California) Sunday Press Enterprise (September 6, 1964) page 39 Excellent photo with three people for size comparison. The most pachycaulous cycad is Cycas thouarsii at up to {{cvt|150|cm}} diameter.{{cite web| url= https://www.conifers.org/zz/Cycadales.php | title= Gymnosperm Database - Cycadales | last= Earle | first= Christopher | date= | access-date= November 24, 2021}} The tallest pachycaul is the Andean wax palm (Ceroxylon quindiuense), at heights of up to {{cvt|66|m}},{{cite book| last= Corner| first= Prof. E.J.H. | date= 1966 | title= Natural History of Palms | location= Berkeley, Calif. | publisher= Univ. Calif. Press | page= 289}} and around {{cvt|41|cm}} in diameter. The most pachycaulous cactus are the barrel cacti (Echinocactus platyacanthus), with primary growth up to {{cvt|1.3|m}} diameter.{{cite book| last1= Britton | first= Nathan L. | last2= Rose | first2= Joseph N. | date= 1963|edition=reprint| title= The Cactaceae - Volume 3 | location= New York | publisher= Dover Pubs. Inc.| page= 170}} The largest caudiciforme-type pachycaul is the African baobab (Adansonia digitata); one specimen of which, called the Glencoe baobab (from Hoedspruit, Limpopo, South Africa) has a basal diameter (not girth) of {{cvt|16|m}}.{{cite book| last= Esterhuyse |first= Neels |display-authors=etal | date= 2001 | title= Remarkable Trees of South Africa | location= Pretoria |publisher= Briza Pubs | pages= 6 (table) and 156 & 159}} 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 {{cvt|5|mm}} each year{{cite journal | last= Claassen | first= Isabel | date= February 1987| title= A Saad Semi-human Succulent | journal= South African Panarama | volume= 32 | issue= 2 | page= 24 }} to the palm Pigafetta elata which can grow {{cvt|2.7|m}} or more in one year.{{cite journal | last= Hodel | first= Donald R. | date= July 1993 | title= Growth of Some Palms in Tahiti | journal= Principes | volume= 37 | issue= 3 |pages= 376-378 }}

Examples occur in these genera:{{cite book |title=The Baobabs: Pachycauls of Africa, Madagascar and Australia |first=G. E. |last=Wickens |author2=Pat Lowe |year=2008 |publisher=Springer |isbn=978-1-4020-6430-2 |pages=139–140}}

See also

References

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Category:Plant morphology

Category:Plant anatomy

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