Attalea (plant)

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Attalea
Tall, single-stemmed palm standing alone in a field of grass with scattered shrubs and palms. The low hills in the background are forested. The leaves are all angled above horizontal, and are shorter than the stem. A single brownish-yellow infructescence is visible just below the leaves. The lower half of the stem is bare, but the upper half has old leaf-based still attached. Ferns and a strangler fig grow on the upper part of the stem just below the leaves, rooted in the old leaf bases.
Attalea brasiliensis
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Clade: Commelinids
Order: Arecales
Family: Arecaceae
Subfamily:
Arecoideae
Tribe: Cocoseae
Genus: Attalea
Kunth
Type species
Attalea amygdalina
Kunth
Diversity
Between 29 and 67 species
Synonyms[1]

Attalea is a large

pinnately
-leaved, non-spiny genus includes both small palms lacking an aboveground stem and large trees. The genus has a complicated taxonomic history, and has often been split into four or five genera based on differences in the male flowers. Since the genera can only be distinguished on the basis of their male flowers, the existence of intermediate flower types and the existence of hybrids between different genera has been used as an argument for keeping them all in the same genus. This has been supported by recent molecular phylogenies.

Between 29 and 67 species are recognised in the genus, with estimates of as many as 100. Incomplete

Pleistocene megafauna
.

Description

A view of the crown of a palm tree from below: Dark green leaves emerge in a radial pattern from the trunk of the tree, above old, dried leaf bases from which the leaves have been cut off. Small ferns grow on them, wedged between the old leaf bases and the trunk of the palm. Between the dried leaf bases and the green leaves there are several brown inflorescences, each of which lies below a reddish-brown bract which is larger than the inflorescence.
Detail of the crown of Attalea maripa showing leaf arrangement and inflorescences

Attalea is a genus of

acaulescent palms (ones which lack an aboveground stem).[2] The number of leaves per individual varies from about three to thirty-five; larger plants tend to have more and longer leaves.[2]

Inflorescences are large, branched and borne among the leaves.[2] The inflorescence consists of a main axis—the peduncle and the rachis—and a series of smaller branches, the rachillae. The rachillae, which bear the flowers, emerge from the rachis. The peduncle is the main stalk, connecting the rachis with the stem.[3] Inflorescences either consist entirely of male flowers, or are predominantly female with a few male flowers.[2] Fruit usually have two or three seeds, although fewer or more are present in some species, and are usually brown, yellow, orange-brown or purple when mature.[2]

Four different types of male flowers exist. On the basis of these flower types, the genus has often been split into four genera—a more narrowly defined Attalea, Orbignya, Maximiliana, and Scheelea.

anthers, while the other groups have straight ones. The petals of those placed in Maximiliana are much shorter than the stamens, while those placed in Scheelea and a more narrowly defined Attalea have petals that are longer than the stamens.[3] Five species do not fit easily into any of these groups; this fact has been used as an argument in favour of considering this group a single genus.[3]

Taxonomy

Cocos nucifera

Syagrus

Lytocaryum (nested within Syagrus)

Attalea

Simplified phylogeny of members of the subtribe Attaleinae, based on seven WRKY gene loci.[4]

Attalea has been placed in the

Polyandrococos,[7] Parajubaea, Butia, and Jubaea.[4]

Disagreement exists as to whether Attalea should be considered a single genus, or a group of related genera. In their 1996 Field Guide to the Palms of the Americas,

Gloria Galeano, and Rodrigo Bernal combined all the species in the subtribe Attaleinae (as it was then defined) into a single genus, Attalea. In his 1999 Taxonomic Treatment of Palm Subtribe Attaleinae, American botanist Sidney F. Glassman divided the group into five genera—a more narrowly defined Attalea, Orbignya, Maximiliana, Scheelea and Ynesa,[3] although he thought it likely that Ynesa colenda, the only member of that genus, was actually a hybrid.[8] Rafäel Govaerts and John Dransfield recognised a single genus in their 2005 World Checklist of Palms,[9] and Jean-Christophe Pintaud continued this usage in his 2008 review of the genus.[3]

The multigenus approach is based solely on the structure of the male flowers; no other characters could be consistently associated with one genus or another.[10] Four of the genera—Attalea (in a narrow sense), Orbignya, Maximiliana and Scheelea—correspond to four different types of male flowers found within the genus. However, a few species have flowers that are intermediate between these four types, including A. colenda (which Glassman placed in its own genus, Ynesa) and this has been used as an argument for the single-genus approach. The fact that there are several hybrids between species that would be considered different genera under Glassman's five-genus system was also used as an argument for placing them in a single genus.[3] Molecular phylogenetic work by Alan Meerow and colleagues concluded that multi-genus approach did not produce monophyletic groups, but treating Attalea as a single genus did.[6]

Cintia Freitas and colleagues identified three main clades within the genus based on the nuclear WRKY gene family. The first of these, a group of species from the coastal Atlantic Forest region in Brazil all of which had been placed in Attalea in the narrow sense, was termed the Attalea-like clade. This group was a sister to the other two clades. The second group, which they called the Scheelea-like clade, consisted of most of the species formerly placed in Scheelea, together with several that had been placed in Attalea (narrowly defined) and Orbigyna. The third group consisted mainly of species formerly placed in Orbigyna and Maximiliana; they called this the Orbigyna-like clade. Despite the existence of three well-supported clades, Freitas and colleagues concluded that the concept of Attalea as a single genus was best supported by their evidence.[6]

History

The genus Attalea was first described

medicinal plants.[2] The type species is A. amygdalina, a Colombian endemic.[12] The genera Maximiliana and Orbignya were described by Carl Friedrich Philipp von Martius in 1826[13] and 1837[14] respectively. Scheelea was described by Hermann Karsten in 1857,[15] and Ynesa by Orator F. Cook in 1942.[16]

Species

Main article: List of Attalea species
Five young palm trees planted together in a group, with a wooden bench below them: The trunks of the palms are marked with alternative pale and dark rings, and are only one-quarter to one-half the length of the leaves.
Attalea crassispatha, a Haitian endemic, is the most geographically isolated species in the genus.

Experts disagree about the number of species in the genus Attalea (broadly defined). In 1965, Dutch taxonomist Jan Gerard Wessels Boer estimated that as many as 100 species may be in the genus. In their 1996 Field Guide to the Palms of the Americas Andrew Henderson and coauthors recognised 29 species in the genus, while Sidney Glassman recognised 65 species in his 1999 treatment of the group. Largely following Glassman's lead, Rafaël Govaerts and John Dransfield recognised 67 species in their 2005 World Checklist of Palms. An important element of this disagreement is the decision by Glassman to define species more narrowly than Henderson. As a result, what Henderson interpreted as variation within species, Glassman took as differences between morphologically similar species. This problem is complicated by the fact that many of these species are poorly represented in herbarium collections. The large size of the leaves, inflorescences and fruit of many Attalea species makes them difficult to collect. In addition, many important collections, including type specimens, have been lost or destroyed.[3] Sparse or incomplete collections make it difficult to differentiate variation within a single species from variation between different species.[3][10] Taxonomic uncertainty is exacerbated by frequent hybridisation between species.[6]

The three recent treatments (Henderson and coauthors, Glassman, and Govaerts and Dransfield) recognised a total of 73 species, but only 20 species are accepted by all of them. The remainder account for either nine species or more than 40. For example, what Andrew Henderson considered a single species, Attalea attaleoides,[17] other authors have considered a species complex consisting of four or five species. Glassman doubted the validity of A. attaleoides as a species, and described four new species from material that had previously been attributed to A. attaleoides—A. camopiensis, A. degranvillei, A. guianensis and A. maripensis. Govaerts and Dransfield accepted both Glassman's four species and A. attaleoides. However, Jean-Christophe Pintaud was of the opinion that A. guianensis, A. maripensis and A. attaleoides were all very similar, and thought it likely that they all represented the same species.[3]

Another species complex in Attalea includes A. speciosa and related species. Henderson (1995) recognised A. speciosa and A. spectabilis, considering the latter to either be an acaulescent form of A. speciosa or a hybrid between A. microcarpa and it. Govaerts and Dransfield accepted A. spectabilis, but Glassman considered it a dubious taxon. Attalea vitrivir was recognised as a distinct species by Michael Balick and coauthors;[18] Glassman and Govaerts and Dransfield concurred, but Henderson considered it part of A. speciosa. Glassman also described a fourth member of this group, A. brejinhoensis, and it is accepted by Govaerts and Dransfield.[3]

Reproduction and growth

Male inflorescence of Attalea sp. swarming with insects.
MHNT

Attalea species are

monoecious—male and female flowers are separate, but are borne by the same plant.[2] Various species have been described as being insect-pollinated, including A. phalerata,[19] while pollination in A. colenda and A. speciosa, has been attributed both to insects and wind.[20][21] The fruit are animal-dispersed.[2]

Seed germination is remote tubular[22]—during germination, as the cotyledon expands it pushes the young shoot away from the seed.[23] After germination, the stem initially grows downward before turning to grow upward and produce the aboveground stem.[24] This produces a "saxophone shaped" belowground portion of the stem.[25] The fact that the shoot tips of Attalea seedlings are underground it likely to contribute to their fire-tolerance.[2]

Distribution

Species range across the Neotropics from Mexico in the north to Bolivia, Paraguay, and southern Brazil in the south,[3] from low elevations in coastal Brazil to up to 1,600 m (5,200 ft) above sea level in the Andes.[6] According to Govaerts and coauthors, three species are found in Mexico, four in Central America, and 62 in South America. Three species are present in the Caribbean—two in Trinidad and Tobago, along the southern edge of the region, and one in Haiti.[26]

Habitat and ecology

Scarlet macaw feeding on Attalea fruit.

Attalea includes both large trees and small, acaulescent palms, which occupy a number of different ecological niches. Dense stands of some of the larger species are conspicuous elements on the landscape, while smaller species are found in both in the forest understorey and in savannas.[3]

Disturbance has been implicated in the formation of vegetation dominated by large Attalea species.[2] In seasonally dry Amazonian forests, the density of large adult A. maripa palms was correlated with canopy openness;[25] the species also dominates savannas formed by repeated forest fires in Trinidad and Tobago.[27] A. speciosa forms pure stands in many parts of Brazil where natural forest vegetation has been cleared.[28] Similarly, stands of A. funifera in Bahia, Brazil (which are cultivated for piassava fibre) are managed using fire—the seedlings survive cutting and burning, and are able to dominate burned forest patches.[29]

The fruit are dispersed by animals; fruit which are not dispersed frequently suffer seed predation by

collared peccaries, deer, and primates. Rodents, including agoutis, fed upon the fruit, and as the fruit availability declined, they fed on the seeds.[32] Other dispersers of Attalea fruit include crested caracaras, which consume the fruit and disperse the seeds of A. phalerata in the Brazilian Pantanal.[33]

Uses

Attalea species have a long history of human use. Carbonised

oil palms, with A. speciosa among the most important economically.[2] Products extracted from A. speciosa were reported to support over 300,000 households in the Brazilian state of Maranhão in 2005,[35] and in 1985 it was estimated to support over 450,000 households throughout the Brazil.[28] Piassava fibres, extracted from the leaf bases of A. funifera, are commercially important,[2] and generated about US$20 million in annual income to Brazilian farmers in 1996.[36]

References

  1. ^ a b "Attalea Kunth in F.W.H.von Humboldt, A.J.A.Bonpland & C.S.Kunth, Nov. Gen. Sp. 1: 309 (1816)". World Checklist of Selected Plant Families. Retrieved 2007-02-24.
  2. ^
    ISBN 0-691-08537-4
    .
  3. ^ a b c d e f g h i j k l Pintaud, Jean-Christophe (2008). "An overview of the taxonomy of Attalea (Arecaceae)" (PDF). Revista Peruana de Biología. 15 (supl. 1): 055–063.
  4. ^
    PMID 19806212
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  5. JSTOR 25070242
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  6. ^
    doi:10.1111/boj.12466
    .
  7. Meerow
    et al. recognised it as a distinct genus in their analysis.
  8. ^ Glassman, Sidney F. (1999). "A Taxonomic Treatment of the Palm Subtribe Attaleinae (Tribe Cocoeae)". Illinois Biological Monographs. 59: 1–414.
  9. ^ "WCSP". World Checklist of Selected Plant Families. Archived from the original on May 17, 2008. Retrieved 2010-04-02.
  10. ^
    JSTOR 2419239
    .
  11. S2CID 12177917
    .
  12. ^ "Attalea amygdalina". World Checklist of Selected Plant Families. Retrieved 2010-02-17.
  13. ^ "Maximiliana". World Checklist of Selected Plant Families. Retrieved 2010-02-17.
  14. ^ "Orbignya". World Checklist of Selected Plant Families. Retrieved 2010-02-17.
  15. ^ "Scheelea". World Checklist of Selected Plant Families. Retrieved 2010-02-17.
  16. ^ "Ynesa". World Checklist of Selected Plant Families. Retrieved 2010-02-17.
  17. ISBN 978-0-19-508311-8
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  18. ^ Balick et al.. 1987, Anderson and Balick 1988
  19. S2CID 19066490
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  20. S2CID 22885187
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  21. JSTOR 2388234
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  22. ISBN 0-935868-30-5
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  23. S2CID 45335410
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  24. doi:10.1590/S0044-59672004000300009
    .
  25. ^ a b Salm, Rudolfo (2005). "The importance of forest disturbance for the recruitment of the large arborescent palm Attalea maripa in a seasonally dry Amazonian forest". Biota Neotropica. 5 (1).
  26. ^ Govaerts, R.; J. Henderson; S.F. Zona; D.R. Hodel; A. Henderson (2010). "World Checklist of Arecaceae". The Board of Trustees of the Royal Botanic Gardens, Kew. Archived from the original on February 21, 2007. Retrieved 2010-02-27.
  27. JSTOR 1948518
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  28. ^
    S2CID 43133375
    .
  29. ^ Voeks, Robert A.; Sergio G. da Vinha (1988). "Fire Management of the Piassava Fiber Palm (Attalea funifera) in Eastern Brazil" (PDF). Yearbook, Conference of Latin Americanist Geographers. 14: 7–13. Archived from the original (PDF) on 2011-07-20. Retrieved 2010-03-03.
  30. S2CID 19296719.[permanent dead link
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  31. PMID 18320062
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  32. JSTOR 2960574
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  33. ^ Galetti, Mauro; Paulo R. Guimarães Jr. (2004). "Seed dispersal of Attalea phalerata (Palmae) by Crested caracaras (Caracara plancus) in the Pantanal and a review of frugivory by raptors" (PDF). Ararajuba. 12 (2): 133–135.[permanent dead link]
  34. S2CID 46582757
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  35. S2CID 153617434
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  36. S2CID 84211050
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