Sika refers to custard apple, which belongs to the Annonaceae family and is a deciduous small tree; the bark is thin, gray-white, and multi-branched. The leaves are thin and papery, oval-lanceolate, with pale green backs; the lateral veins are flat above and raised below.

The flowers are solitary or 2-4 are gathered on the top of the branches or opposite to the leaves, green and yellow; the flower buds are lanceolate; the sepals are triangular and slightly hairy; the outer whorls of petals are narrow, thick, and oblong. ; Stamens oblong, septate wide; carpels hairless, each carpel has 1 ovule.

The fruit consists of a plurality of round or oval mature carpels that are slightly connected and easy to separate, forming an aggregated berry that is spherical or heart-shaped, conical, hairless, yellow-green, and covered with white frost on the outside. The flowering period is from May to June, and the fruiting period is from June to November.

It is cultivated in Zhejiang, Taiwan, Fujian, Guangdong, Guangxi, Hainan and Yunnan provinces in China. Native to tropical America; now cultivated in tropical areas around the world. The fruit is edible and looks like a lychee, hence the name "cherimoya". It is a famous fruit in tropical areas.

Extended information:

Annona loves light and tolerates shade. With sufficient light, the plant grows robustly and has thick leaves. Custard apple needs a warm climate and adequate precipitation, and is intolerant of frost and cold weather. The average optimal growth temperature for common custard apples is 25-32℃, with an average minimum temperature of 15-25℃. The optimal average temperature for fruit ripening is 25-30℃.

The critical temperature for the safe overwintering of custard apple trees is 0℃. Most custard apples are semi-deciduous fruit trees and enter natural dormancy or forced dormancy caused by environmental conditions in late winter or early spring. Dormancy protects the plant from the effects of late frosts or drought in winter and spring. Appropriate low temperatures in winter will help accelerate leaf fall and promote germination.

But the role of low temperature in inducing germination is not as necessary as in other deciduous fruit trees. The temperature during fruit ripening should be neither too low nor too high. When encountering low temperatures, especially low temperatures below 13°C, physiological diseases will occur in fruits, while excessive temperatures will cause premature ripening and easily cause fruit rot.