Bergenia purpurascens (Hook. f. & Thomson) Engl.

Bergenia purpurascens (Hook. f. & Thomson) Engl., commonly known as “Rockfoil,” is a perennial herbaceous plant in the Saxifragaceae family and the Bergenia genus. It is also known by other names such as “Yunnan Rockfoil” and “Blue-flowered Bergenia.” The plant can grow up to 52 cm in height. It has a thick rhizome, and all leaves are basal, leathery, with rounded tips, and margins that are wavy-toothed or nearly entire. The leaf base is wedge-shaped, with small glandular pits on both surfaces, and the stipule sheath margin is hairless. The inflorescence is a panicle with glandular hairs on the flower stalk. The sepals are leathery and narrowly ovate, while the petals are purplish-red and broadly ovate. The ovary is ovoid. It blooms and bears fruit from May to October.

Distribution: Bergenia purpurascens is found in southwestern Sichuan, northern Yunnan, and southern and eastern Tibet in China. It also occurs in northern Myanmar, northeastern India, northern Bhutan, and Nepal. It typically grows under forests, in thickets, alpine meadows, and rocky crevices at altitudes ranging from 2700 to 4800 meters.

Medicinal Uses: The entire plant contains compounds such as bergenin, a type of coumarin. The rhizome is used in traditional medicine; it is non-toxic and is used to treat conditions like weakness, dizziness, coughing due to overexertion, hemoptysis (coughing up blood), hematuria (blood in urine), leukorrhea (white discharge), and abscesses. However, it should be used with caution by those with fever due to external conditions and a weak constitution.

Horticultural Value: Bergenia purpurascens has a long flowering period, vibrant flower colors, and evergreen, glossy leaves. It is ideal for planting in rock gardens or under trees, bringing a natural wild charm to the landscape. It can also be potted and placed indoors as an ornamental plant for both foliage and flowers.

Morphological Characteristics

Bergenia purpurascens is a perennial herb that grows to a height of 13-52 cm. It has a thick rhizome covered with scales. All leaves are basal, leathery, obovate, narrowly obovate to nearly elliptical, or occasionally broadly obovate to almost long elliptical. The leaves are 5.5-16 cm long and 3-9 cm wide, with rounded tips and wavy-toothed or nearly entire margins. The base of the leaf is wedge-shaped, and the leaf surfaces are hairless with small glandular pits. The petiole is 2-7 cm long, and the stipule sheath margin is hairless. The flower stalk has sparse glandular hairs.

The inflorescence is a panicle, 3-23 cm long, with glandular hairs on both the flower stalks and branches. The sepals are leathery, narrowly ovate, 6.5-7 mm long, and 2-4 mm wide, with rounded tips. The petals are purplish-red, broadly ovate, 10-16.5 mm long, and 7-7.8 mm wide, with rounded or slightly notched tips and a narrowed base forming a claw of 2-2.5 mm in length, with multiple veins. The stamens are 6-11 mm long, and the ovary is ovoid, 6.7-7.5 mm long, with two styles measuring 5.3-7.5 mm in length. The chromosome number is 2n=34. The flowering and fruiting period is from May to October.

Cultivation Techniques

Fertilization significantly impacts the above-ground growth of Bergenia purpurascens. Plants treated with compost and humus soil exhibit stronger growth, with more tillers per plant, more leaves per plant, and darker leaf color. The number of tillers per plant increases by 1.8-2.3, and the number of leaves by 2-3, compared to untreated plants. The root systems of plants treated with compost and humus soil are more developed, with stronger root activity, potentially showing more pronounced differences over time.

After flowering, it is essential to prune away the spent flower clusters promptly to maintain a tidy plant shape, water moderately, and avoid sun exposure.

Habitat

There are 10 species of the genus Bergenia, scattered across Asia, with 7 species found in China, 3 of which are endemic. Bergenia purpurascens is distributed in southwestern Sichuan, northern Yunnan, and southern and eastern Tibet, growing at altitudes of 2700-4800 meters under forests, in thickets, alpine meadows, and rocky crevices. It also occurs in northern Myanmar, northeastern India, northern Bhutan, and Nepal. The type specimen was collected in India.

Growth Habits

Wild Bergenia purpurascens mainly grows in high-altitude regions of 2700-4200 meters, in soils that are brown or dark brown forest soils with a pH of 6.2-6.7. The primary vegetation in its habitat includes mixed forests of conifers and broad-leaved trees, often interspersed with many rhododendrons. Bergenia purpurascens thrives under the shade of thickets on shady slopes or in rock crevices, with the most vigorous growth occurring on shady slopes with deep humus layers. It prefers cool and light conditions, grows well in partial shade, is drought-tolerant, cold-tolerant, but not heat-tolerant, with an optimal growth temperature of 12-20°C.

Propagation Methods

The germination rate of seeds is highest in spring, though it is only 22.5%. Spring-sown seedlings grow faster and reach the five-leaf stage 10-20 days earlier than those sown in summer and autumn, due to the higher vitality of spring seeds. The seeds are small, making it challenging to select uniformly mature seeds.

Propagation through rhizome cuttings involves treating the rhizome of Bergenia purpurascens and planting it in a seedbed. Rhizome cuttings are easy to root, with an average survival rate of 97.2% when planted in spring, summer, and autumn. The highest survival rate is in summer due to the optimal temperature and humidity conditions, but spring cuttings grow the fastest, reaching the five-leaf stage 10-30 days earlier than those planted in summer and autumn. Growth is best with 85% shade in open ground.

Pest and Disease Control

Bergenia purpurascens is commonly affected by leaf spot disease and aphid infestations. Leaf spot disease can be controlled with a 600-fold dilution of 65% wettable zinc fungicide, while aphids can be controlled with a 1000-fold dilution of 2.5% rotenone emulsion.

Economic Value

Bergenia purpurascens is easy to cultivate, with purple-brown leaves and bright purplish-red flowers, making it an attractive ornamental plant for both foliage and flowers. It is suitable for mass planting by water edges, among rocks, or along the edges of lawns, and is widely used as a ground cover plant.

Medicinal Uses The entire plant contains bergenin and other coumarin compounds. The rhizome is used in traditional medicine; it is non-toxic and used to treat conditions such as weakness, dizziness, cough due to overexertion, hemoptysis, hematuria, leukorrhea, and abscesses. However, it should be used with caution by those with fever due to external conditions and a weak constitution.

Properties: Sweet and astringent in taste, cool in nature. It enters the liver, lung, and spleen meridians.

Functions: Tonifies and strengthens the body, stops coughing and bleeding. It is primarily used for treating weakness and dizziness, coughing up blood due to overexertion, hemoptysis, hematuria, and leukorrhea.

Dosage: For internal use, 6-12 grams are decocted in water. For external use, the fresh plant is mashed and applied, or powdered and mixed with water for application.

Precautions: It should be used with caution in individuals who are weak and have a fever due to external conditions.