The Annonaceae are woody trees, shrubs and vines comprising about 130 genera and 2,300 species. The leaves are simple, alternate, lack stipules, and generally are distichously arranged in flat sprays. The flowers are bisexual and actinomorphic, possessing 3 whorls of perianth with 3 segments in each whorl. The elongated floral axis also bears many helically disposed stamens and several to many simple pistils. All of the floral parts are distinct. The stamens are very short, consisting of the fertile central anther portion, a distal pad of fleshy connective tissue, and a short fleshy basal portion. The stamens are generally so tightly packed on the receptacle that often only the fleshy connective tissue of each is exposed. The pistils each have a superior ovary with one locule and 1-many parietal ovules. Sectioned seeds reveal channels or partitions in the ruminate endosperm. The pistils generally remain distinct and develop into berry-like fruits but sometimes they coalesce into multiple fruits like the custard apple.

Each "thumbnail" image below is linked to a larger photograph.

Cananga odorata, ylang ylang. Note the distichous leaves in the first photo.  The perianth consists of 3 whorls with 3 appendages in each whorl.  The outer appendages or sepals are small by comparison to the 2 inner whorls.  However, they are persistent and readily visible in the early fruiting stage depicted in the 3rd photo.  In this species the pistils remain distinct and the cluster of fruit at the left in the 4th photo was derived from a single flower.  
Artabotrys hexapetalus, ylang ylang. Note three whorls of perianth, one of the inner petals has been removed to reveal the numerous greenish stamens and the yellowish pistils.
Polyalthia suberosa. The trimerous nature of the perianth is apparent. The carpels of the apocarpous gynoecium remain distinct into the fruiting stage in this species.  The section through a seed reveals ruminate or compartmentalized endosperm and a small embryo.
Annona cherimola, cherimoya
Annona muricata, soursop. Small tree from tropical America with edible, dark green, heart-shaped fruit covered with fleshy, curved, "prickles". Each "prickle" corresponds to a pistil.  The pistils are initially distinct but coalesce during development of the aggregate fruit.  The pulp makes a refreshing drink or "icee". The close-up of the flower reveals the inner two whorls of trimerous perianth and hundreds of tightly packed stamens forming a yellowish cup around the base of the central cluster of numerous tiny whitish pistils.
Annona squamosa, sugar apple
Monodora myristica.  Although the 3-merous condition of the perianth that is typical for the family is seen in this species, the gynoecium is exceptional in being syncarpous.

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