Aiphanes

Genus of spiny palms native to tropical South and Central America and the Caribbean

Aiphanes is a genus of spiny palms which is native to tropical regions of South and Central America and the Caribbean. There are about 26 species in the genus (see below), ranging in size from understorey shrubs with subterranean stems to subcanopy trees as tall as Most have pinnately compound leaves (leaves which are divided into leaflets arranged feather like, in pairs along a central axis); one species has entire leaves. Stems, leaves and sometimes even the fruit are covered with spines. Plants flower repeatedly over the course of their lifespan and have separate male and female flowers, although these are borne together on the same inflorescence. Although records of pollinators are limited, most species appear to be pollinated by insects. The fruit are eaten by several birds and mammals, including at least two species of amazon parrots. Carl Ludwig Willdenow coined the name Aiphanes in 1801. Before that, species belonging to the genus had been placed in Bactris or Caryota. The name Martinezia had also been applied to the genus, and between 1847 and 1932 it was generally used in place of Aiphanes. Max Burret resurrected the name Aiphanes in 1932 and laid the basis for the modern concept of the genus. Aiphanes is most closely related to several other genera of spiny palms—Acrocomia, Astrocaryum, Bactris and Desmoncus. Two species are widely planted as ornamentals and the fruit, seeds or palm heart of several species have been eaten by indigenous peoples of the Americas for millennia.

Aiphanes is a genus of spiny palms ranging from tall subcanopy trees to small shrubs with subterranean stems growing in the forest understorey. Its name combines the Ancient Greek ai, meaning "always", with phaneros, meaning "evident", "visible" or "conspicuous". In their 1996 monograph on the genus, botanists Finn Borchsenius and Rodrigo Bernal pointed out that "ironically, species of Aiphanes are generally very hard to spot and find in dense vegetation and, accordingly, are among the most poorly collected neotropical palms". Leaves are spiny but the degree varies both within and among species. Leaf sheaths are always densely spiny, but the spines usually become smaller and sparser towards the ends of the leaves.

Aiphanes species are pleonanthic—they flower repeatedly over the course of their lifespan—and monoecious, meaning that there are separate male and female flowers, but individuals plants bear both types of flowers. In Aiphanes, male and female flowers are borne together on the same inflorescence. Usually only a single inflorescence is borne at each node, although A. gelatinosa often bears then in groups of three at a single node. The inflorescence usually consists of a main axis consisting of a peduncle and a rachis. The rachis bears rachillae, which are smaller branches which themselves bear the flowers, while the peduncle is the main stalk connecting the rachis with the stem of the plant. In some species there is second order branching—the rachillae themselves are branched and the flowers are borne on these branches. Flowers are usually borne in groups of three—one female flower together with two male flowers. In some species groups of four flowers (two male and two female) have been reported. At the far end of the inflorescence, away from the axis of the tree, pairs of male flowers replace the triads of male and female flowers. Flower colour is poorly known. It must be recorded from live plants, since preserved flowers lose their colour over time, and records of these species in the wild are incomplete. Male flowers tend to fall into two groups—those with cream or yellow flowers and those with some amount of purple in the flowers. Female flowers are even less well known than male flowers. The sulcus is a furrow which runs along the surface of the pollen grain and is usually the site at which pollination occurs. Monosulcate pollen has a single furrow that runs along the pole of the pollen grain. Meridionosulcate pollen have a furrow that runs along the equator of the pollen grain. Trichotomosulcate pollen, on the other hand, has three furrows. The outer layer of the pollen is covered to a greater or lesser extent with ridges, spines or warts. This "sculpting" tends to be more pronounced in species that are fly pollinated and less pronounced in those that are pollinated by beetles or bees. Seeds are light brown with a thin seed coat (or testa) and white endosperm, which is sweet and tastes somewhat like coconut.

The genus Aiphanes ranges from Hispaniola (the Dominican Republic) and Panama in the north, to Trinidad and Tobago in the east, across Colombia and down along the Andes to Bolivia. In Brazil it only occurs along the border with Peru. Aiphanes is primarily South American—one species (A. hirsuta) is present in Panama and two others (A. horrida and A. minima) are found in the Caribbean. Aiphanes minima, which is endemic to the insular Caribbean, is the only species absent from the South American mainland. Although A. horrida has been reported from Guyana and southern Venezuela these reports have not been verified with herbarium vouchers. Aiphanes horrida is the most widely distributed species. It ranges from Trinidad to Bolivia but is absent from Ecuador and northern Peru. Other species have narrower ranges with one centre of diversity in western Colombia and Ecuador and another minor one in northeastern Peru. A. leiostachys and A verrucosa—and three others considered vulnerable to the same threat—A. chiribogensis, A. duquei and A. lindeniana. Rodrigo Bernal and Gloria Galeano expanded this list in a 2005 review of the status of Colombian palms. They listed two species as critically endangered—A. graminifolia, a species that was first described in 2002, and A. leiostachys (which was classified as endangered in the IUCN Red List). They classified two species as endangered—A. acaulis and A. parvifolia—and two species as vulnerable—A. gelatinosa and A. pilaris. They also classified six species as near threatened—A. erinacea, A. hirsuta, A. lindeniana (vulnerable according to the IUCN Red List), A. linearis, A. macroloba and A. simplex. The threats to these species were not listed, but Jens Christian Svenning reported that A. erinacea was threatened by logging given its limited distribution and poor ability to regenerate in disturbed forests. In addition to these, A. deltoidea, which is widely distributed across the western Amazon Rainforest, is present at such low densities that it was classified as a rare species by Francis Kahn and Farana Moussa in 1994.

Aiphanes species are palms of the forest understorey and subcanopy. The most widely distributed species, A. horrida, occurs both in tropical dry forest and in more humid forest types, but there is a gap in its distribution which coincides with the wettest forests of the upper Amazon Basin. Two other species, A. minima and A. eggersii, are also found in drier environments; A. eggersii is found in areas receiving as little as of precipitation annually. The remaining species are found in montane forests at high elevations or in wet—often very wet—lowland forests, including areas receiving as much as of annual precipitation. The fruit of A. horrida is rich in vitamins and energy and likely to be eaten by many animals. Oilbirds are reported to eat its fruit and disperse its seeds. Squirrels are also reported to consume the fruit, despite the spiny nature of the tree. and is also considered a potentially important food species for the critically endangered Puerto Rican amazon (Amazona vittata). Several species show clumped distributions. Dispersal limitation has been invoked to explain the clumped distribution of adults and limited recruitment of seedlings in both A. erinacea in Ecuador and A. minima in Puerto Rico.

Aiphanes species have a long history of human use. The remains of carbonised seeds thought to belong to A. horrida have been found in archaeological sites in Colombia dating back to about 2800 BP; seeds of this species are still consumed and are traded in local markets. Aiphanes horrida is also widely planted as an ornamental, as is A. minima. The fruit or seeds of A. deltoidea, A. eggersii, A. linearis and A. minima are all consumed locally. The palm heart of A. macroloba is consumed by the Coaiquer people of northwestern South America. Aiphanol, a compound isolated from A. horrida, has shown significant inhibitory activity against cyclooxygenases; inhibition of these enzymes can provide relief from the symptoms of inflammation and pain.