An elongated circumferential leaf base formation present on some species of palm is called a crownshaft.
The leaf bases of some pinnate leaved palms (most notable being Roystonea regia or the royal palm but also including the genera Areca, Wodyetia and Pinanga) form a sheath at the top of the trunk surrounding the bud where all the subsequent leaves are formed. [1]
The crownshaft takes the form of a column above the main trunk and beneath the main crown of leaves and is nothing but the collection of the leaf bases of the plant, all tightly wrapped around one another. It is usually green in color but may be a different color from that of the leaves themselves, including white, blue, red, brownish or orange. Each layer of the crownshaft is a distinct leaf base and is usually made of a tough fibrous material with a feel similar to leather and in many parts of the world, it is cured and used to prepare covers, sheets and roofing material. The leaf base of some palms is also used to extract coir.[ citation needed ]
The oldest leaf forms the outermost layer of the crownshaft. Eventually the lowest palm frond dies back, the outer layer of the crownshaft splits, the leaf unwraps and pulls away from the trunk exposing the new crownshaft surface. In time the old leaf separates at the base and falls away leaving the distinct rings and ridges of the leafbase scars seen on the trunks of many species of palm. These scars usually fade over time and the distance between two successive scars is an approximate indicator of the speed of growth of the palm. In tropical conditions when growing conditions are good, the palm grows faster and the gap between scars is large; conversely when growing conditions are not optimum, plant growth is slow and the gaps are narrower. Juveniles and younger palms usually grow faster than adults; this is demonstrated by the larger gaps between scars at the base as compared to the top.[ citation needed ]
In some species of palm the shaft is fairly indistinct because the leaf bases are not wrapped around each other very tightly, and the shaft becomes extended and “loose.”
Some palm species do not form a shaft until past the juvenile stage.
Phoenix is a genus of 14 species of palms, native to an area starting from the Canary Islands in the west, across northern and central Africa, to the extreme southeast of Europe (Crete), and continuing throughout southern Asia, from Anatolia east to southern China and Malaysia. The diverse habitats they occupy include swamps, deserts, and mangrove sea coasts. Most Phoenix species originate in semi-arid regions, but usually occur near high groundwater levels, rivers, or springs. The genus is unusual among members of subfamily Coryphoideae in having pinnate, rather than palmate leaves; tribe Caryoteae also have pinnate or bipinnate leaves.
Rhopalostylis sapida, commonly known as nīkau, is a palm tree endemic to New Zealand, and the only palm native to mainland New Zealand.
Roystonea is a genus of eleven species of monoecious palms, native to the Neotropics, in the Caribbean, the adjacent coasts of Florida in the United States, Mexico, Central America and northern South America. Commonly known as the royal palms, the genus was named after Roy Stone, a U.S. Army engineer. It contains some of the most recognizable and commonly cultivated palms of tropical and subtropical regions.
Acanthophoenix is a genus of flowering plants in the palm family from the Mascarene Islands in the Indian Ocean, where they are commonly called palmiste rouge. A genus long in flux, three species are currently recognized, though unsustainable levels of harvesting for their edible palm hearts have brought them all to near extinction in habitat. They are closely related to the Tectiphiala and Deckenia genera, differing in the shape of the staminate flower. The name combines the Greek words for "thorn" and "date palm".
Roscheria is an endangered, monotypic genus of flowering plant in the palm family. The genus is named for Albrecht Roscher, a 19th-century German explorer, and the epithet for its single species R. melanochaetes derives from Latin and Greek meaning 'black' and 'bristle', alluding to the spines covering the trunks. They naturally occur on the Mahé and Silhouette Islands of Seychelles where they grow in mountainous rainforest and are threatened by habitat loss.
Bismarckia is a monotypic genus of flowering plant in the palm family endemic to western and northern Madagascar, where it grows in open grassland.
Aphandra is a monotypic genus of flowering plants in the palm family native to the Amazon rainforest vegetation in South America. Its only species is Aphandra natalia, sometimes called mastodon palm or fiber palm, and is used by indigenous peoples in the construction of brooms and other products. This plant is commercially exploited for its edible fruits, and for its leaf sheath and petiole fibers. This fiber is almost equal to the fiber extracted from Attalea funifera and Leopoldinia piassaba, which is called piassava.
Calyptrocalyx is a monoecious genus of flowering plant in the palm family found in Papua New Guinea and the nearby Maluku Islands. Ranging from small to large, the palms in this genus are increasingly found in cultivation owing largely to their purple, red, and orange colored, new foliage. At least 26 species have been described while others, known only by local names, have not yet received a taxonomic account. Palms formerly classified within Paralinospadix have been incorporated into this genus. It is named from 2 Greek words meaning 'covered' and 'calyx'.
Actinorhytis is a monotypic genus of flowering plant in the palm family found in Oceania and southeast Asia. The lone species, Actinorhytis calapparia is a rain forest inhabitant and has very large fruit. The genus name is from two Greek words meaning 'ray' and 'fold' which describe the endosperm of the seed.
Clinosperma bractealis is a species of palm tree in the palm family
Dictyocaryum is a monoecious genus of flowering plant in the palm family found in South America. It is closely related to the genus Iriartea; they are commonly called araque or palma real. As many as eleven species have been described but this number is reduced to three in most current accounts. The genus name translates from two Greek words meaning "net" and "nut", describing the thick network of raphe fibers around the seed.
Dictyosperma is a monotypic genus of flowering plant in the palm family found in the Mascarene Islands in the Indian Ocean. The sole species, Dictyosperma album, is widely cultivated in the tropics but has been farmed to near extinction in its native habitat. It is commonly called princess palm or hurricane palm, the latter owing to its ability to withstand strong winds by easily shedding leaves. It is closely related to, and resembles, palms in the genus Archontophoenix. The genus is named from two Greek words meaning "net" and "seed" and the epithet is Latin for "white", the common color of the crownshaft at the top of the trunk.
Cyphokentia macrostachya is a species of palm endemic to New Caledonia.
Iguanura is a monoecious genus of flowering plant in the palm family from Southeast Asia, commonly called pinang. Closely related to the Heterospathe palms, they are noted for producing a wide variety of fruit forms. Its name combines the Spanish word for "lizard" with the Greek word for "tail".
Leopoldinia is a mostly monoecious genus of flowering plant in the palm family from northern South America, where they are known as jará palm or pissava palm. The two known species are commercially important, especially L. piassaba, which yields sustenance and construction material. The genus is named for Maria Leopoldina, archduchess of Austria, and Brazilian empress.
Lepidorrhachis is a monotypic genus of flowering plant in the palm family restricted to Lord Howe Island. The genus name for the single, monoecious species, Lepidorrhachis mooreana, comes from two Greek word meaning "scale" and "rachis", and the epithet honors Charles Moore, first director of the Sydney Botanical Gardens. The common name is Little Mountain Palm.
Mauritiella is a dioecious genus of flowering plant in the palm family found in South America where it is commonly called buriti. It is named after the similar and closely related genus Mauritia.
Nenga is a monoecious genus of flowering plant in the palm family. It is native to Southeast Asia and commonly called pinang palm. The genus name is based on a corruption of a Javanese term for a plant now classified within Pinanga.
Oraniopsis is a monotypic genus of flowering plant in the palm family from Queensland, Australia, where the only known species, Oraniopsis appendiculata, grows in mountainous rain forest. Dioecious and extremely slow growing, the name means "similar to Orania" and the Latin epithet translates to "appendaged".
Dransfieldia is a monotypic genus of flowering plant in the palm family from western New Guinea where the lone species Dransfieldia micrantha grows in dense rain forest. Discovered in 1872, 134 years passed before DNA testing revealed its proper placement. With no close relatives, it is a delicate, pinnate-leaved palm named after John Dransfield, former palm expert at the Kew Royal Botanic Gardens.