Annona

Annona
Annona squamosa
Annona muricata
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Magnoliids
Order:	Magnoliales
Family:	Annonaceae
Genus:	Annona L.[1]
Species
Some 100-150, see text.
Synonyms
Guanabanus Mill. Raimondia Saff. Rollinia A. St.-Hil. Rolliniopsis Saff.[2]

Annona is a genus of flowering plants in the pawpaw/sugar apple family, Annonaceae. It is the second largest genus in the family after Guatteria,^[3] containing approximately 166^[4] species of mostly neotropical and afrotropical trees and shrubs.^[5] The generic name derives from anón, a Hispaniolan Taíno word for the fruit.^[6] Paleoethnobotanical studies have dated Annona exploitation and cultivation in the Yautepec River region of Mexico to approximately 1000 BC.^[7] It has several common names, including Guanabana, Graviola and Soursop.

Currently, seven Annona species and one hybrid are grown for domestic or commercial use, mostly for the edible and nutritious fruits; several others also produce edible fruits.^[8] Many of the species are used in traditional medicines for the treatment of a variety of diseases, though their efficacy as a medicine has yet to be validated scientifically. Several annonacaeous species have been found to contain acetogenins, a class of natural compounds with a wide variety of biological activities.^[9][10]

Description

Annona species are taprooted, evergreen or semideciduous, tropical trees or shrubs.^[5] This fruit typically grows in areas where temperature does not drop below 28 °F, especially Cuba, Jamaica, and the Philippines. However, it has also been known to grow in certain areas of Florida.

• Trunks: The trunks have thin bark that has broad and shallow depressions or fissures which join together and are scaly giving rise to slender, stiff, cylindrical and tapering shoots with raised pores and naked buds.^[5]
• Leaves: Leaf blades can be leathery or thin and rather soft or pliable, bald or hairy.^[5]
• Flowers: The flowering stalks rise from axils, or occasionally from axillary buds on main stems or older stems, or as solitary flowers or small bundle of flowers. Usually, the three or four deciduous sepals are smaller than the outer petals that do not overlap while in bud. Six to eight fleshy petals in two whorls—the petals of the outer whorl are larger and do not overlap; inner petals are ascending and distinctively smaller, and nectar glands are darker pigmented. Numerous stamens that are ball, club-shaped, or curved and hooded or pointed beyond anther sac. Numerous pistils, attached directly to the base, are partially united to various degrees with distinct stigma, with one or two ovules per pistil; the style and stigma are club-shaped or narrowly conic.^[5]
• Fruits: One fleshy, ovate to spherical fruit is produced per flower. Each fruit consists of many individual small fruits or syncarps, with one syncarp and seed per pistil. Seeds are bean-like with tough coats; the seed kernels are toxic.^[5]
• Pollination: Dynastid scarab beetles appear basic within the genus Annona. Those species of Annona which are more morphologically derived, as well as all Rollinia spp., possess reduced floral chambers and attract small beetles such as Nitidulidae or Staphylinidae.^[11]

Toxicology

Annonacin is a neurotoxin found in Annona muricata seeds.

The compound annonacin contained in the seeds of some members of Annonaceae such as Annona muricata (soursop) is a neurotoxin and it seems to be the cause of a neurodegenerative disease. The only group of people known to be affected live on the Caribbean island of Guadeloupe and the problem presumably occurs with the consumption of plants containing annonacin. The disorder is a so-called tauopathy associated with a pathologic accumulation of tau protein in the brain. Experimental results demonstrated for the first time that the plant neurotoxin annonacin is responsible for this accumulation.^[12]

Selected species

The following is a list of some of the more important species. Many of them have significant agricultural, medicinal, pharmaceutical, and other uses. Synonyms appear in the sublist.^[13]

Insects and diseases

Annona species are generally disease-free. They are susceptible to some fungi and wilt. Ants are a problem, since they promote mealybugs on the fruit.^[14]

Insects

Fungi

Nematodes

Algae

• Cephaleuros virescens
• Cephalosporium spp.
• Paecilomyces spp.^[17]

Diseases

• Diplodia natalensis (Dry fruit rot)
• Fruit rot^[15]

References

External links

• Media related to Annona at Wikimedia Commons
• Data related to Annona at Wikispecies
• Type Collections of Neotropical Annonaceae – Annona – has pictures and details on these and other Annona species

Images

• 

  Atemoya (A. cherimola × A. squamosa)

• 

  Cherimoya (A. cherimola) plantation

• 

  Soursop (A. muricata)

• 

  Sugar apples (A. squamosa)

• 

  Sugar Apple (A. squamosa) interior

• 

  Sugar apple interior

• 

  Sugar apple exterior

• 

  Annona muricata

• 

  A.crassiflora fruit

Halved annona fruit

Annona tree, Merida, Yucatan, Mexico

Anonna fruit