Annonaceae

The Annonaceae are a family of flowering plants consisting of trees, shrubs, or rarely lianas commonly known as the custard apple family or soursop family. With 108 accepted genera and about 2400 known species, it is the largest family in the Magnoliales. Several genera produce edible fruit, most notably '' Annona'', '' Anonidium'', ''Asimina'', ''Rollinia'', and ''Uvaria''. Its type genus is ''Annona''. The family is concentrated in the tropics, with few species found in temperate regions. About 900 species are Neotropical, 450 are Afrotropical, and the remaining are Indomalayan.

Description

The species are mostly tropical, some are mid-latitude, deciduous or evergreen trees and shrubs, with some lianas, with aromatic bark, leaves, and flowers.

; Stems, stalks and leaves: Bark is fibrous and aromatic. Pith septate (fine tangential bands divided by partitions) to diaphragmed (divided by thin partitions with openings in them). Branching distichous (arranged in two rows/on one plane) or spiral. Leaves are alternate, two-ranked, simple, pinnately veined, and have leaf stalks. Stipules absent.

; Flowers: Flower stalks are axillary to (on the opposite side of shoot from) leaf scars on old wood and sometimes from leaves on new shoots. The flowers are usually trimerous; borne singly or in compound inflorescences; bisexual and rarely unisexual. The receptacle might become enlarged, elevated or flat. The outer whorls are inserted below the ovaries, and have valvate (overlapping) or imbricate (nonoverlapping) segments. Usually two to four persistent sepals that are distinct or connate (fused) at the base. Six petals in two unequal whorls of three with larger outer whorls and fleshier inner whorls that might share the same nectar glands, or six to fifteen petals, with impressed veins on their inner face. Ten to twenty (or many more) stamens inserted below the ovary, spirally arranged and forming a ball or flat-topped mass with short and stout filaments and linear to oblong anthers which face outward and open longitudinally. Each flower can have from one to many pistils, distinct to connate, with stigmas distinct. Marginal placentation, each pistil bearing one locule, with one to many ovules. Style short and thick, with terminal stigma.

; Fruits and seeds: Fruits are single berries or coalesce from several pistils (into aggregate fruit, syncarps). Seeds are one to many per pistil; have a fleshy and usually brightly colored cover, have ruminate endosperm (nutritive tissue surrounding the embryo) and are oily.

Systematics

Monophyly and inter-familial systematics have been well supported for Annonaceae by a combination of morphological and molecular evidence. The APG II system places Annonaceae as most closely related to the small Magnoliid family Eupomatiaceae.

In a phylogeny-based reclassification of the family four subfamilies are recognised: Anaxagoreoideae (including just '' Anaxagorea''), Ambavioideae, Annonoideae, and Malmeoideae. A number of the larger genera, including ''Guatteria'', with its 177 species, '' Annona'', and ''Xylopia'' belong to Annonoideae. Together, Annonoideae and Malmeoideae comprise the majority of the species and each are further subdivided into a number of tribes. The subfamilial and tribal classification is followed i
World Annonaceae
which presents an overview of all Annonaceae genera and taxonomic, distribution and photographic information for a large number of species. Keys for the identification of Annonaceae genera (separately for Neotropical, African/Madagascan, and Asian/Australian taxa) are presented in: For a concise bibliographic overview of the taxonomic literature (1900 to 2012) see:

Both plastid DNA markers and morphological characters provide evidence that '' Anaxagorea'' is the sister clade to the rest of the family. This may confirm the hypothesis that morphological traits shared between '' Anaxagorea'' and other Magnoliales species (such as 2-ranked phyllotaxis, monosulcate pollen, and laminate stamens) represent ancestral characters, while derived characters observed in other genera have evolved independently multiple times. The oldest fossil evidence of Annonaceae is described as the genus ''Futabanthus'', from the Late Cretaceous (Coniacian) of Japan, which represents a minimum age of c. 89 million years ago for the most recent common ancestor (crown group) of the family. The ages of Annonaceae clades inferred using fossil evidence and molecular clock-based dating techniques suggests that the pantropical distribution of the family originated subsequent to the break-up of the Gondwanan supercontinent, as the result of a combination of geodispersal tracking the expansion of the boreotropical flora during the Eocene and more recent long-distance dispersal events.

Taxonomic revisions within the subfamily Malmeoideae

The reclassification and establishment of ''Huberantha''

The genus ''Huberantha'' (synonym ''Hubera'') was resolved to be sister to '' Miliusa'', with certain species previously under ''Polyalthia'' being additionally reclassified. This reclassification was highly supported by maximum parsimony, Bayesian analysis, and morphological characters. ''Hubera'' is characterized by reticulate tertiary venation, axillary inflorescences, 1 ovule per ovary, seeds with flat to slightly raised raphes, and other characters. ''Huberantha'''s phylogenetic distance and morphological difference from ''Monoon'' and ''Polyalthia'', distinguish ''Huberantha'' on the generic level. Morphologically, ''Huberantha'' has a finely and densely granular infratectum whereas ''Monoon'' and ''Polyalthia'' have columellate or densely granular infratecta.

Controversy over ''Stelechocarpus/Winitia''

It was proposed that the genus '' Stelechocarpus'', which includes ''S. burahol'' and ''S. cauliflorus'' be reclassified under a new genus ''Winitia'', which is characterized by mixed flowers, multicolumellar stigmas, and columellate/coarsely granular infratectum. This genus was created after phylogenetic analysis that highly supported an unclassified species from Thailand being sister to ''S. cauliflorus'' as a monophyletic group. However this is no longer accepted.

Reclassification of ''Annickia'' as tribe Annickieae

The genus '' Annickia'' was previously included within the tribe Piptostigmateae. However, it is highly supported to being sister to the rest of the Malmeoideae tribes, and weakly supported to being sister to the rest of the Piptostigmateae genera. For these reasons, ''Annickia'' is now classified within its own tribe in the Malmeoideae, the Annickieae.

Subfamilies

The taxonomy of the Annonaceae is based on the Angiosperm Phylogeny Website, which recognises four subfamilies and the extinct genus '' Anonaspermum''

Anaxagoreoideae

Auth.: Chatrou et al. 2012 (monotypic)
* '' Anaxagorea'' St.-Hilaire 1825

Ambavioideae

Auth.: Chatrou et al. 2012
* '' Ambavia'' Le Thomas
* ''Cananga'' (DC.) Hook.f. & Thomson (Ylang-ylang)
* '' Cleistopholis'' Pierre ex Engl.
* '' Cyathocalyx'' Champ. ex Hook.f. & Thomson
* '' Drepananthus'' Maingay ex Hook.f.
* '' Lettowianthus'' Diels
* '' Meiocarpidium'' Engl. & Diels
* ''Mezzettia'' Becc.
* '' Tetrameranthus'' R.E.Fr.

Annonoideae

Tribes and selected genera
* Tribe Annoneae Endlicher 1839
** '' Annona'' L. (synonym ''Rollinia'' A. St.-Hil.)
** ''Asimina'' Adans.
** ''Goniothalamus'' (Blume) Hook.f. & Thomson
* Tribe Bocageeae Endlicher 1839
** '' Bocagea'' A.St.-Hil.
** '' Mkilua'' Verdc.
* Tribe Duguetieae Chatrou & Saunders 2012
** ''Duguetia'' A.St.-Hil.
** '' Pseudartabotrys'' Pellegr.
* Tribe Guatterieae Hooker & Thomson 1855
** ''Guatteria'' Ruiz & Pav.
* Tribe Monodoreae Baill. 1868
** ''Monodora'' Dunal
** '' Uvariopsis'' Engl.
* Tribe Uvarieae Hooker & Thomson 1855
** '' Dasymaschalon'' (Hook.f. & Thomson) Dalla Torre & Harms
** '' Desmos'' Lour.
** '' Fissistigma'' Griff.
** '' Mitrella'' Miq.
** ''Uvaria'' L.
* Tribe Xylopieae Endlicher 1839
** '' Artabotrys'' R.Br.
** ''Xylopia'' L.

Malmeoideae

*Tribe Annickieae Couvreur et al., 2019 (monotypic)
**'' Annickia'' Setten & Maas
*Tribe Piptostigmateae Chatrou & Saunders 2012
Selected genera:
**'' Piptostigma'' Oliv.
**''Sirdavidia'' Couvreur

*Tribe Malmeeae Chatrou & Saunders 2012
Selected genera:
** '' Ephedranthus''
** '' Klarobelia''
** '' Malmea'' R.E.Fr.
** '' Mosannona''
** ''Oxandra'' A.Rich. (black lancewood)
** '' Pseudephedranthus''
** '' Pseudomalmea''
** '' Ruizodendron''

*Tribe Maasieae Chatrou & Saunders 2012 (monotypic)
** '' Maasia'' Mols et al.
*Tribe Fenerivieae Chatrou & Saunders 2012 (monotypic)
** '' Fenerivia'' Diels
*Tribe Phoenicantheae (monotypic)
** '' Phoenicanthus'' Alston
*Tribe Dendrokingstonieae Chatrou & Saunders 2012 (monotypic)
** '' Dendrokingstonia'' Rauschert
*Tribe Monocarpieae Chatrou & Saunders 2012 (monotypic)
** '' Monocarpia'' Miq.
*Tribe Miliuseae Hooker & Thomson 1855
Selected genera:
** '' Alphonsea'' Hook.f. & Thomson
** '' Desmopsis'' Saff.
** ''Huberantha'' (synonym ''Hubera'') Chaowasku
** ''Meiogyne'' Miq. (synonyms: ''Ancana'' F. Mueller; ''Guamia'' Merrill; ''Fitzalania'' F. Muell.; ''Oncodostigma'' Diels, ''Polyaulax'' Backer)
** '' Miliusa'' Lesch. ex A.DC. ('' Saccopetalum'' Bennett)
** '' Mitrephora'' (Blume) Hook.f. & Thomson
** ''Monoon'' Miq. (''Cleistopetalum'' H. Okada, ''Enicosanthum'' Becc., ''Woodiellantha'' Rauschert)
** '' Phaeanthus'' Hook.f. & Thomson
** ''Polyalthia'' Blume
** '' Polyalthiopsis'' Chaowasku
** ''Sageraea'' Dalzell
** '' Sapranthus'' Seem.
** '' Stelechocarpus'' Chaowasku
** '' Wuodendron'' B.Xue, Y.H.Tan & Chaowasku

Uses

Food

The large, edible, pulpy fruits of some members, typically called ''anona'' by Spanish- and Portuguese-speaking people of the family's Neotropical range, include species of '' Annona'': custard apple ('' A. reticulata''), cherimoya ('' A. cherimola''), soursop/guanábana/graviola ('' A. muricata''), sweetsop ('' A. squamosa''), ilama ('' A. diversifolia''), soncoya ('' A. purpurea''), '' atemoya'' (a cross between ''A. cherimola'' and ''A. squamosa''); and biriba (''Rollinia deliciosa'', which may require reclassification under ''Annona''). The names of many of those fruits are sometimes used interchangeably.

Consumption of the neotropical annonaceous plant ''Annona muricata'' (soursop, ''graviola, guanabana'') has been strongly associated as a causal agent in "atypical Parkinsonism". The causative agent, annonacin, is present in the seeds and leaves of many of the Annonaceae, though not in any significant quantity in the fruit flesh. It is thought to be responsible for up to 70% of Parkinsonian conditions in Guadeloupe. Exposure is typically through traditional food and natural medicines.

The American pawpaw (''Asimina triloba'') has an Eastern U.S. distribution and has been investigated as a commercial agricultural crop.

Flower petals from sacred earflower ('' Cymbopetalum penduliflorum'') and from related species '' C. costaricense'' were traditionally used to flavor chocolate before the arrival of cinnamon and the other Old World spices. The dried petals are still used to flavor atoles, pinoles, and coffee.

Folk medicine

The bark, leaves, and roots of some species are used in folk medicines.

Toxicology

The acetogenin compounds, which occur in the fruit, seeds, and leaves of many Annonaceae, including soursop ('' Annona muricata''), are neurotoxins and seem to be the cause of a neurodegenerative disease. The disorder is a so-called tauopathy associated with a pathologic accumulation of tau protein in the brain. Experimental results indicate that acetogenins is responsible for this accumulation.Informationsdienst Wissenschaft:
Tauopathie durch pflanzliches Nervengift
'', 4. Mai 2007

Other uses

Lancewood (''Oxandra lanceolata'') is a tough, elastic, and heavy wood obtained from the West Indies and The Guianas. It was often used for carriage shafts. It is brought into commerce in the form of taper poles of about 6 m in length and from 15 to 20 cm in breadth at the butt. The black lancewood or carisiri of the Guianas is of remarkably slender form.

The yellow lancewood tree ''Calycophyllum candididissimum'', common names lemonwood or degame, is from a different family (Rubiaceae). It is used as an alternative to lancewood and is found in tolerable abundance throughout The Guianas, and used by the Amerinds for arrow-points, as well as for spars, beams, etc. Some bowyers use this wood for making longbows.

Other

* Some species of the family, such as ''Cananga odorata'' (ylang-ylang) also have aromatic oil and are used for perfumes or spices.
* The strong bark is used for carrying burdens in the Amazon Rainforest and for wooden implements, such as tool handles and pegs. The wood is valued as firewood.
* Yellow and brown natural dyes