Dicoytledons of Annonaceae

Asimina triloba

Annonaceae (Custard Apple Family)

Systematic position:

Polypetalae, Thalamiflorae, Ranales.

Field Recognisation:

 Woody shrubs, trees or climbers, wood aromatic, leaves two-ranked, without stipules 3+3+3, stamens numerous, rarely few, gynoecium polycarpellary, apocarpous, superior ovary.

Selected Indian Genera:

Annona squamosa, Cananga odorata, Arta botrys odoratissimus.

Size,distribution,and General Information:

Over 25 genera and 200 species have so far been reported from India, mostly from its peninsular region. Annona is represented by over 120 species, and Xylopia by about 150 species.

Description of the family:

General Habit- Aromatic trees or shrubs, rarely liana-like, or woody climbers(Oxymitra), hook climber(Artabotrys).Bark, leaves and floral parts contain oil ducts.

Root-Extensively branched tap roots.

Stem-Woody, branched, erect, rarely climbing, aerial, hard.

Leaves-Simple, alternate, two-ranked, exstipulate, petiolate, apex acute, obtuse or even mucronate, ovate, obovate, coriaceous, glabrous, unicostate reticulate, gland-dotted and so aromatic.

Inflorescence- Solitary axillary, or terminal, or leaf opposed, sometimes cauliflorous ,i.e. flowers occur on stem.

Flower- Bracteate or ebracteate, ebracteolate, pedicellate, complete, hermaphrodite, rarely unisexual, actinomorphic, rarely zygomorphic, hypogynous.

Calyx- Sepals 3, or sometimes 6 arranged in 2 whorls of 3 each, polysepalous, or rarely basally connate, valvate, rarely imbricate.

Corolla- Generally 6 petals, arranged in two whorls of 3 each, sometimes only 3 petals, polypetalous, valvate or slightly imbricate.

Androecium- Stamens numerous, polyandrous, flimant short and thick,connective continues beyond the anther and produces a dilated head,ad nate,extrorse.

Gynoecium- Carpels numerous, arranged spirally on the receptacle, only 1-3 carpels in Cyathocalyx, apocarpous, superior, unilocular, one to many anatropous ovles in the locule, parietal or sometimes basal or marginal placentation, style short or absent, stigma sessile, simple or trilobed.

Fruits and seeds- Fruits an etaerio of berries in Annona, the berries coalesce with fleshy receptacle, seeds large, endospermous. 

Floral formula:

Economic importance: 

•   Annona.squamosa is cultivated in assam for its edible fruits.Its leaves and seeds have insecticidal properties.

•                A.odoratissimus yields an ethereal oil and also cultivated for its scented flowers.

•             Asimina is cultivated for its edible fruits in America.

•            Cananga odorata is cultivated as an ornamental  tree cause of its sweet smelling flowers.

•           Unona pannosa yields a strong fibre used for paper making and cordage.

• Uraria narum root yield an oil used as a medicine.