1． Apple

Most of the apple varieties cultivated in the world now belong to this species or hybrids of this species and other species. Cotton apples native to my country and introduced cultivated varieties all belong to this species. There are many varieties of this species, three of which are valuable in production:

(1) Daosheng apple

There are many varieties of this species, including dwarf trees or shrubs with a crown height of 5~6m. The branches are prone to adventitious roots and can be propagated by division, layering, cutting and other methods. It can be used as dwarfing or semi-dwarfing rootstock for apples, or as dwarfing rootstock breeding material.

(2) Paradise Apple

This variety is extremely dwarf, about 2m high, and is a shrub type. It can be propagated by division, layering, cutting and other methods. It can be used as apple dwarf stock or dwarf stock breeding material.

(3) Red-fleshed apple

Tree, this variety is characterized by red pigments in the leaves, xylem, pulp and seeds. The sweet red flesh and sour red flesh of Yecheng, Xinjiang, The Shayilamu from Ili and the Hongxinzi from northern Liaoning belong to this variant. It can be used as raw material for breeding red meat varieties.

2． Huahong

Also known as Shaguo, Ringo, Tianzi, Guozi, Naipi, Miguo, Ginkgo, Wenlinlangguo, Asian apple, etc. This species originated in northwest my country and is distributed in North China, the Yellow River Basin, the Yangtze River Basin, and southwest provinces (regions), with the largest number in Northwest and North China. It is a small deciduous tree, 4~7m high, with low branches and large angles. The crown is open and the branches are scattered or drooping. The fruit is flat and round, yellow or full red, with sparse fruit spots, weighing 20~40g, the core is close to the top, the calyx is shrunk, and the fruit stem is short. It matures in July to August. It can be eaten fresh or used for processing. It cannot be stored and transported. In production, grafting is often used for propagation, with Semen japonicus or Catalpa japonica as rootstock. This species can also be used as apple rootstock, which is more cold-resistant, but not salt-alkali tolerant or drought-resistant.

3． Catalpa japonica

Also known as Begonia fruit, Ringo, Catalpa japonica, Round-leaf Begonia, Haihong, etc. This species is native to my country and is distributed in northwest, north China, northeast and south of the Yangtze River. It is a deciduous small tree, 3~8m high, with cylindrical branchlets, young branches densely pubescent, and old branches gray-brown and hairless. The fruit is oval or conical, 2~2.4cm in diameter, yellow-orange or slightly red, with persistent calyx and protruding lower surface; harvested from mid-to-late August to early September. This species has wide adaptability, is cold-resistant, flood-resistant, and drought-resistant, and performs better in saline-alkali soil than the mountain stinger. It is also resistant to apple woolly aphids and root cancer diseases, and has strong grafting affinity. Except for a few improved varieties that can be eaten fresh, most of these fruits are used for processing and can also be used as raw materials for breeding. Michulin once used it to cross apples and breed many excellent cold-resistant varieties.

4． Xifu Begonia

Also known as Little Begonia, Haihong, Clear Thorn Begonia, and Zimu Begonia. Originating in my country, it is distributed in Hebei, Shandong, Shanxi, Henan, Shaanxi, Gansu, Liaoning, Yunnan and other provinces. Small tree, 3~6m high, upright, with multiple trunks, sometimes in the form of clusters. The fruit is nearly spherical, red, with a diameter of 1~1.5cm. The biggest difference from Begonia is that the fruit has obvious calyx depressions, most of the calyxes fall off, a few persist, and the protrusions under the sepals are not obvious. This species has strong resistance, grows well in saline-alkali soil, and is more resistant to yellow leaf disease. It can be used as apple rootstock, such as Baleng Begonia and Leng Begonia in Huailai, Hebei, Flat-top Hot Flower Red and Flat-top Cold Flower Red in Changli; Difficult to use in Laiwu, Shandong Yan, late Ringo from Yidu; Ringo from Taigu, Shanxi and other places. The seedlings grow a lot and have many branches. They stop growing late and can be grafted in the year of sowing.

5. Shanjingzi

Also known as Shandingzi, Shanshanzi, Linjingzi, etc. This species is produced in Heilongjiang, Jilin, Liaoning, Inner Mongolia, Hebei, Shandong, Shaanxi, Gansu and other places. Deciduous tree, more than 10m high, with a broad and round crown; the fruit is nearly spherical, weighing about 1g, red or yellow, and matures in October. It has strong cold resistance, and some types can withstand low temperatures of -50°C. In Northeast China, Hebei, Shanxi and other northern regions, it is one of the main apple rootstocks.

6. Maoshan Jingzi

It is also known as Maoshan Dingzi, Liaoshan Dingzi and Tangli wood. It is native to Northeast my country, North China and Northwest China. Tree, up to 15m high, with oval or obovate fruits, slightly larger than Vitex japonica. This species is used as the main rootstock of apples in Northeast China, Hebei Province, and northern Shanxi Province.

7． Henan Haitang

The native names are big-leaf tea, winter green tea, and mountain brocade. It is native to my country and distributed in Henan, Shanxi, Shaanxi, Gansu, Hebei, Sichuan and other provinces. Shrub or small tree, about 7m high. The fruit is nearly spherical, 0.8~1cm in diameter, yellow-red or reddish-purple, and matures in September. It is used as apple rootstock in Henan area. Some types such as Wuxiang crabapple and apple grafting have dwarfing phenomenon.

8. Hubei Begonia

Also known as Huahongcha, Qiuzi, Tea Begonia, Wild Flower Red, etc. This species is distributed in Hubei, Hunan, Jiangxi, Jiangsu, Zhejiang, Anhui, Fujian, Guangdong, Sichuan, Shaanxi, Gansu, Yunnan, Guizhou, Henan, Shandong, Shanxi and other provinces. Shrub or tree, 1~8m high, similar to vitex, but the young leaves, calyx and pedicels are purple-red, with 3~4 ventricles. Pingyi sweet tea from Shandong and Nanshipingye Begonia from Yunnan both belong to this species. It can be used as apple rootstock in the central, southwestern and southeastern provinces of my country. Resistant to flooding, but not drought. This species has parthenogenetic ability. The seeds are developed from embryos formed by nucellar wall cells. They can maintain maternal traits, have small variability, and do not transmit viruses.

9． Begonia flower

Also known as flower begonia, crabapple and sea red. It is native to my country and is distributed in Hebei, Shaanxi, Jiangsu, Zhejiang, Yunnan and other provinces. Deciduous small trees and large shrubs, up to 8m in height. The fruit is nearly spherical, about 2cm in diameter, yellow or yellow-green, with shallow calyx depressions and fallen sepals. The tree has strong growth, salt-alkali tolerance, cold resistance, and moderate waterlogging resistance. It is suitable for cultivation on sandy beaches and is a good rootstock for apple orchards on sandy beaches.

10． Three-leaf crabapple

It is native to my country. Wild in Liaoning, Shandong, Shaanxi, Gansu, Jiangxi, Zhejiang, Hubei, Hunan, Sichuan, Guizhou, Fujian, Guangdong, Guangxi and other places. The fruit is divided into two types: red fruit and yellow fruit. It is called camellia fruit in Qingdao and Wendeng, Shandong, mosaic sour wine in Qinling, Shaanxi, and wild yellow fruit in Tongzi, Guizhou. It can be used as apple rootstock.

11. Xinjiang wild apple

Also known as Sewei apple, it is produced in Ili and Tacheng areas in western Xinjiang. Small tree or tree, 2~8m high, fruit shape, color, quality and maturity vary greatly among different types. It is used as apple rootstock in Shaanxi, Gansu, Xinjiang and other places and grows well.

12. Lijiang Mountain Jingzi

Also known as Lijiang Mountain Dingzi and Himalayan Mountain Jingzi. Distributed in northwest Yunnan, southern Sichuan Province and southeastern Tibet, it grows in valleys and forests at an altitude of 2400~3800m. Local farmers in Lijiang, Yunnan, use it as rootstock of Shaguo. The fruit shape is larger than that of Vitex japonicus, spherical, with 4 to 5 ventricles. It is used as apple rootstock in southwestern Sichuan.

13. Taiwanese Ringo

Produced in Taiwan Province, it is also known as Taiwanese Begonia. The fruit of this species is large, fragrant, slightly astringent when eaten raw, and can be eaten after being salted. Generally used for seed propagation, the seeds have strong germination ability and can be used as rootstocks and original breeding materials for apple cultivation in subtropical areas.

14． Xiaojin Begonia

Also known as Iron Catalpa. It is native to Xiaojin, Markang, Li County and other places in Sichuan, my country. Tree, 8~12m high, oval or obovate fruit, 1~1.2cm in diameter, red and yellow, mature in late September. This species has a well-developed root system, many fibrous roots, and has various stress tolerances such as drought resistance, poor soil tolerance, waterlogging tolerance, disease resistance, and salt-alkali tolerance. It is a promising apple rootstock for resisting iron deficiency chlorosis. This species has apomictic reproduction characteristics, has good grafting compatibility with apples, has a dwarfing effect, has early fruiting, high yield and high quality.

Except for the above 14 species of Malus plants in my country, the rest are mainly for ornamental purposes and should be studied and utilized in fruit tree production areas.