Houpo is a plant of the Magnolia family and is a commonly used traditional Chinese medicine. The bark, root bark, flowers, and seeds can all be used medicinally, with the bark being the most commonly used part. Houpo has the effects of resolving dampness and stagnation, promoting qi circulation and relieving wheezing, promoting digestion and resolving phlegm, and expelling wind and alleviating pain. The seeds have the additional effect of improving vision and boosting qi. However, due to excessive harvesting of the bark, the resources of houpo are becoming increasingly scarce, and it has been listed as a protected resource in China.
I. Morphological Characteristics
1. Plant of the Magnolia Family
It is a perennial deciduous tall tree, reaching a height of 8-19 meters and a diameter of 0.2-0.45 meters.
2. Stem
The stem is straight and not curved, with few branches. The outer bark is grayish-brown, with longitudinal cracks on the trunk and older branches. It has gray spots and the inner bark is purple or dark with an oily and spicy taste, commonly known as ginger spicy taste.
3. Branches
The branches are round and stout, spreading outwards. The young branches are pale yellow and may have silky hairs. The top of the branch has narrow ovate-conical buds. The winter buds are as large as a thick brush head and have slightly wavy edges.
4. Leaves
The leaves are alternate and clustered on the top of the small branches. The leaf blade is leathery, inverted-ovate or inverted-elliptic in shape, 16-30 cm long and 12-20 cm wide. The apex is blunt or shortly pointed, and the base is wedge-shaped or rounded, with entire or slightly wavy margins. The leaf surface is smooth, and the back has a reticulate vein pattern, covered with gray hairs and powdery substance. There are 20-40 prominent veins, and the petiole is 2-5 cm long.
5. Flowers
They bloom in early summer from early April to mid-May. The flowers open at the same time as the leaves. They are large, white, and fragrant, with a diameter of about 12-16 cm. The flower stalk is stout and covered with brown hairs. The perianth consists of 9-12 fleshy petals. There are numerous stamens arranged in a spiral, and the pistils are red and arranged neatly on the elongated receptacle.
6. Fruits
The fruit is a aggregate follicle, woody, elongated oval in shape, about 10-15 cm long, resembling corn kernels, hence the nickname "houpao corn". Each chamber usually contains one seed, occasionally two. The seeds are triangular-ovate, with a waxy and fresh red outer seed coat and a black inner seed coat, with a thick and hard seed coat. The fruit matures from late September to late October.
II. Biological Characteristics
Houpo is a tree species specific to mountainous areas, tolerant to cold, and a positive tree species. It mostly grows in mountainous areas at an altitude of 300-2700 meters, but it is recommended to plant it at an altitude of about 800-2200 meters. Although houpo can grow in higher mountainous areas, it is difficult for the seeds to mature. Below 700 meters in altitude, the seedlings grow faster, but the adult trees grow slower. Above 1700 meters in altitude, the seedlings grow slower while the adult trees grow faster.
Houpo prefers to grow in sunny slopes with fertile soil and deep soil layers. It often grows together with fir trees and prefers loose, fertile, well-drained acidic to neutral soils with a high content of humus. It is a heliophilous tree species and prefers a moist, cool, humid, rainy, and well-illuminated environment, but it is afraid of extreme heat, cold, and waterlogging. High temperatures are not conducive to the growth and development of the plants and make them more susceptible to diseases. Seedlings are afraid of strong light.
Houpo requires an average annual temperature of 16-18°C during germination and growth, with a minimum temperature not lower than -8°C. The annual rainfall ranges from 800 to 1400 millimeters, and the relative humidity is about 70%-90%. Houpo is a slow-growing tree species, with a height of only 30-45 centimeters for one-year-old seedlings, and the growth of young trees is slightly faster.
