Family: ANNONACEAE
Although called pawpaw in Australia, this species is not a true pawpaw, but is related to the custard apples. Other common names include custard banana and Michigan banana. There are other Asimina spp but none show the promise of this one.
A deciduous shrub or low tree, native to north America and growing, under favourable condi-tions, up to 12 m. It occurs naturally as a thicket understorey in open woodland. In dryer areas it tends to hug the watercourses. The straight trunk rarely exceeds 30 cm in diameter but some have been measured to 150 cm. A single tree can sucker out to about a quarter of an acre in ideal conditions, if allowed. It is able to cope with snow conditions.
Wood ash is said to be a good fertiliser for the tree but better results were observed from using old plaster from a building. The tree has brittle branches and is very prone to wind damage. It prefers well drained, fertile soil, rich in organic matter. Severe spring frosts can destroy flowers resulting in crop loss. It is tolerant of fairly saline water.
The fruit is the largest native fruit of North America (weighing up to 300 grams) and develops in autumn. When fully ripe the fruit skin is dark brown or almost black. The soft creamy fruits are said to have the flavour of banana custard and are delicious eaten raw. They can be dried and are also used for making preserves, pies, puddings and desserts. The yellow fruiting varieties are said to be superior to the white. Nutritionally, the fruit comprises carbohydrate -16.8% (of this, 16% is sucrose, 35% reducing sugars and 52% reducing sugars after inversion), protein - 5.2%, fat - 0.9%, ash - 0.5%, water - 76.6%. Handling the fruit can cause skin rashes on some people. Pigs and poultry are reported to not eat the fruit.
The wood is light (specific gravity of 0.3969), spongy, coarse grained, weak and of little value, although it had been used in local construction in the pioneer years. The inner bark was stripped from the branches in the early spring and made into a string which was used to manufacture fishing nets, fishing lines and rope.
The seeds contain a colourless and tasteless alkaloid called asimine, which acts on the brain of animals causing somnolence then stupor and finally unconsciousness. It also has emetic properties. The bark contains the alkaloid analobine and was once used in medicine.
The plant can be grown from seed which needs stratification. Given the wide natural occur-rence of the plant in the wild, it would probably pay to try to match seed source conditions to local environment. Germination seems to occur best in very warm conditions. The seedlings are usually planted out while dormant, when they reach 300 mm, although some advocate direct sowing the seed. There may be a root associate which promotes fast and healthy growth, but as yet this has not been isolated. Cultivars exist and the plant is readily grafted and also grows from root cuttings and layering. Fruiting seems to benefit from cross - pollination.