Rehmannia glutinosa

Rehmannia glutinosa

The Chinese foxglove (Rehmannia glutinosa (Gaertn.) Steud.) is a herbaceous species belonging to the Gesneriaceae family.

Systematics –
From a systematic point of view it belongs to:
Eukaryota Domain,
Kingdom Plantae,
Subarign Tracheobionta,
Spermatophyta superdivision,
Magnoliophyta Division,
Magnoliopsida class,
Subclass Asteridae,
Order Scrophulariales,
Gesneriaceae family,
Genus Rehmannia,
R. glutinosa species.
The terms are synonymous:
– Chirita chanetii H.Lév .;
– Digitalis glutinosa Gaertn .;
– Gerardia glutinosa (Gaertn.) Bunge;
– Rehmannia chanetii (H.Lév.) H.Lév .;
– Rehmannia chinensis Libosch. ex Fisch. & C.A.Mey .;
– Rehmannia glutinosa (Gaertn.) Libosch. ex Fisch. & C.A.Mey .;
– Rehmannia glutinosa f. huechingensis (Chao & Shih) P.G.Xiao;
– Rehmannia glutinosa f. purpurea Matsuda;
– Rehmannia glutinosa var. hemsleyana Diels;
– Rehmannia glutinosa var. huechingensis Chao & Shih;
– Rehmannia sinensis (Buc’hoz) Libosch. ex Fisch. & C.A.Mey .;
– Sparmannia sinensis Buc’hoz.

Etymology –
The term Rehmannia is named after Joseph Rehmann (1788–1831), a St. Petersburg physician.
The specific epithet Glutinosa comes from gluten gluten, glue: glutinous, viscous.

Geographic Distribution and Habitat –
Rehmannia glutinosa is a plant native to northern and northeastern China, particularly in the province of Hunan. It is present spontaneously in the territories of Gansu, Hebei, Henan, Hubei, Jiangsu, Liaoning, Shaanxi, Shandong, Shanxi and up to Korea.
Its habitat is that of well-drained stony soils along the edges of roads, in the woods, in the mountain slopes, on the sides of the paths, on the slopes of the hills and on the ridges of the fields, from sea level up to about 1,100 meters.

Description –
Rehmannia glutinosa is a small hairy, rhizomatous, rosette perennial herbaceous plant that normally grows 0.3 to 0.6 m in height and is covered with long, soft, gray-white glandular hairs all over the plant.
It has a thick and reddish yellow root. The fresh and dried roots and rhizomes have a soft texture, with deep longitudinal wrinkles on the outer surface and a darker central bark.
The stem is erect, simple or branched from the base.
The basal leaves are usually pinkish. The leaves are stemmed that gradually or abruptly decrease in size or shrink to upward bracts. The leaf blade is ovate to strictly elliptical, 2-13 cm long and 1-6 cm wide, tapered base, irregularly crenated or obtuse serrated to toothed margin.
The inflorescences are sometimes scapose. The flowers are axillary and solitary or in terminal, pedicellated racemes. Bracts may be present or absent. The chalice is 5 (-7) -lobato. The corolla is purplish red or yellow, tubular; slightly curved or straight tube, compressed dorso-ventrally, with 2 braids from the base of the tube to the throat; limb 2 lips, 5 lobes. The stamens are 4, didynamic, rarely 5 and 1 smaller than the other 4 included; coherent anthers in pairs, fertile loculi. Ovarian base with disc, with 2 niches, rarely with 1 niche; numerous ova. 2-lamellar stigma.
Flowering normally occurs from April to June.
From the fertile flowers, seed capsules are formed, from ovoid to strictly ovoid, 1-1.5 cm long which consist of almost 300-400 seeds. The fruits begin to ripen from May to early June.

Cultivation –
Rehmannia glutinosa is a perennial herbaceous plant that has been used since remote times in its natural state for local use as food and medicine. It is widely grown for its medicinal rhizomes in China, and is also grown as an ornamental plant.
It is a plant likely to be hardy down to around -25 ° C if the plants are dry, but softer, hairy leaves are likely to rot in hot, humid winters.
For its cultivation it requires a light and humus-rich substrate and prefers a sandy soil with a neutral to acid pH. It also requires a warm and sunny location.
Plants are prone to fungal infections, especially when grown in humid conditions.
Propagation occurs by seed; sowing should be done in autumn or spring in a sheltered seedbed.
As soon as the plants are manageable, they should be placed in single pots for their first winter and sheltered in a greenhouse. The transplant should be done in late spring or early summer.
It can also be propagated by root cuttings in winter, by division in spring or by basal cuttings in late spring or early summer.

Customs and Traditions –
Rehmannia glutinosa is known by various names, depending on where it grows or is known. It takes the names of: shēng dì huáng (Chinese: 生地黄). It is often sold as gān dì huáng (Chinese: 干 地 黄), gān meaning “dried”. Other names are: Chinese foxglove, Chinese rehmanniae Radix, Chinese RR, Di Huang, Gun-Ji-Whang, Japanese Rehmanniae Radix, Shu Di Huang, Sook-Ji-Whang and To-Byun.
This plant has been considered a panacea in traditional Chinese medicine, mainly in combination with other herbs. The dried Rehmannia rhizome is said to “nourish the yin” and remove heat from the blood, and is used as a liver tonic.
Documented historical uses include the treatment of anemia, cancer, constipation, diabetes, fatigue, bacterial and fungal infections, hypertension, insomnia, tinnitus, inflammatory conditions, burns, impotence and osteoporosis.
Rehmannia glutinosa is one of the 50 basic herbs used in traditional Chinese medicine.
Numerous chemical constituents have been reported from fresh or processed roots of R. glutinosa including iridoids, phenethyl alcohol, glycosides, cyclopentanoid monoterpenes and norcarotenoids.
Among the edible uses the leaves are used even if there are few details about it.
The root can be eaten cooked, boiled nine times before being eaten. This suggests that the root is somewhat toxic, or at least has a very bitter taste. After boiling it nine times (and presumably throwing the water away each time), there will be very little left in the way of vitamins and minerals.
In Chinese medicine it is commonly used in herbal medicine, where it is one of the most popular tonic herbs.
The roots are antibacterial, antiseptic, cardiac, diuretic, febrifuge, hemostatic, hypoglycemic and tonic.
As mentioned, they are used in the treatment of a wide range of ailments.
The charred root serves to stop bleeding and tone the spleen and stomach.
The fresh root is used to treat thirst, infectious disease outbreaks and bleeding from pathological heat.
The dried root is used to treat bleeding due to lack of blood and to nourish the vital essence.
The prepared root is used to treat dizziness and palpitations due to anemia or lack of blood, chronic tidal fever, night sweats, dry mouth, low back pain and nocturnal emissions.
The root is an ingredient in ‘Four Things Soup’, the most widely used female tonic in China. The other species used are Angelica sinensis, Ligusticum wallichii and Paeonia lactiflora.
The crushed leaves are used in the treatment of scaly eczema or psoriasis.

Preparation Method –
Of Rehmannia glutinosa, the root tuber is used for medicinal use.
The roots of cultivated plants are harvested in the fall or early winter, while wild plants are harvested in early spring.
These can be used fresh or dried.
The root can be prepared in four different ways: charred, prepared (but no preparation details are provided) when it is called Shu Di Huang, and fresh or dried when it is called Sheng Di Huang.

Guido Bissanti

Sources
– Acta Plantarum – Flora of the Italian Regions.
– Wikipedia, the free encyclopedia.
– Useful Tropical Plants Database.
– Conti F., Abbate G., Alessandrini A., Blasi C. (ed.), 2005. An annotated checklist of the Italian vascular flora, Palombi Editore.
– Pignatti S., 1982. Flora of Italy, Edagricole, Bologna.
– Treben M., 2000. Health from the Lord’s Pharmacy, Advice and experiences with medicinal herbs, Ennsthaler Editore.
Photo source:
– https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:808644-1

Warning: Pharmaceutical applications and alimurgical uses are indicated for informational purposes only, they do not represent in any way a medical prescription; therefore no responsibility is taken for their use for curative, aesthetic or food purposes.