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 to diaphragmed. Branching distichous or spiral. Leaves are alternate, two-ranked, simple, pinnately veined, and have leaf stalks. Stipules absent.
; Flowers: Flower stalks are axillary to 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 or imbricate segments. Usually two to four persistent sepals that are distinct or connate 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 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. Seeds are one to many per pistil; have a fleshy and usually brightly colored cover, have ruminate endosperm and are oily.

Systematics

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, 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 in 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 are presented in: For a concise bibliographic overview of the taxonomic literature 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 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 of Japan, which represents a minimum age of c. 89 million years ago for the most recent common ancestor 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 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

Anaxagorea St.-Hilaire 1825
Ambavioideae