Annona

Longitudinal section of a flower Annona with morphological components.

Esteries of the synchropic fruit Annona cherimola: each comes from a single leaflet and about 100-200 form the fruit set, the Chirimoya. The whitened pulp that surrounds the seeds is the sweet and edible part of the fruit.

An example of seeds (Annona cherimolaChirimoya.

Annona cherimola (chirimoya) - Example of the internal structure of a seed: equatorial cutting evidence of the coriaceous endocarp and the tegument penetrating the fissures (laminiform) of endosperma. They also see clearly the micropile and its thread.

Annona is, after Guatteria, the genus with the second most species in the family Annonaceae. It contains about 170 accepted species, of the more than 360 described, most are Neotropical and Afrotropical trees and shrubs. Paleoethnobotanical studies estimate the date of exploitation and cultivation of Annona in the Yautepec River region of Mexico at approximately 1000 BC. C.

Description

They are evergreen or semi-evergreen trees or shrubs. Trunks have thin scaly bark with shallow, wide fused depressions or fissures. The slender shoots are tough and cylindrical with bare, open-pored buds.
Shovel-shaped leaves that can be leathery or thin and quite soft and flexible, with or without hairiness.
Flower stalks arise from axils, occasionally from axillary buds on main stems or older stems, as solitary flowers or in small clusters. They normally have 3-4 drooping sepals, smaller than the outer petals and not overlapping while remaining bud-like. 6 to 8 fleshy petals in two whorls - the outer whorl petals are larger and not imbricated; the interior ones are ascending, noticeably smaller and with darker pigment nectary glands. The numerous stamens are ball-shaped, elongated at the end or curved and hooded or tapered outside the antheral sac. Numerous pistils attached directly to the base, with different degrees of partial union and with distinguishable stigma. One or two ovules per pistil; style and stigma in the form of a club or closed cone.
The fruit in number of 1 per flower, between oval or spherical. The fruit is a berry syncarp consisting of many small individual or ethereal fruits; an etherium and a seed per pistil. The seeds are bean-shaped with a leathery endocarp and a ruminate endosperm (laminate ruminations) intimately penetrated by the integument.

Pollination of this genus is basically carried out by beetles of the Dynastinae subfamily. The more morphologically derived Annona species, as well as the Rollinia species, have small flower chambers, thus attracting small beetles such as Nitidulidae or Staphylinidae.

Uses and cultivation

Currently, seven species of Annona plus one hybrid are cultivated for domestic or commercial use, primarily for their nutritious fruits. Many of the species are used in traditional medicine for the treatment of various diseases. Polyketides, a class of naturally occurring compounds with a wide variety of biological activities and pharmacological properties such as bullatacin, annonacin, and the annonines, have been found in several of the species.

Taxonomy

The genus was described by Carlos Linnaeus and published in Species Plantarum 1: 536. 1753. The type species is: Annona muricata L.

Etymology

Annona: generic name derived from the Taíno Annon.

Selected species

• Annona cherimola
• Annona contrerasii
• Annona diversifolia
• Annona edulis
• Annona muricata
• Annona reticulata
• Annona squamosa