Inula Japonica: Exploring Growth, Uses, and Medicinal Benefits

Inula japonica, a perennial herb of the Asteraceae family, has a short rhizome that runs horizontally or ascends diagonally, with somewhat robust fibrous roots.

Single stems sometimes grow in clusters of 2-3, with head-shaped inflorescences measuring 3-4 cm in diameter, arranged loosely in umbel-shaped formations. The achene, or dry fruit, is 1-1.2 mm long and cylindrical in shape.

Flowering occurs from June to October, while fruiting takes place from September to November. Inula japonica is primarily used to treat cold cough, phlegm accumulation, chest fullness, asthma, excessive phlegm, vomiting, belching, and hard epigastric distention.

The standard dosage is typically 3-9 grams. The plant is warm and dispersing, thus it is not suitable for those suffering from yin-deficiency cough or fluid-injury dry cough.

Moreover, due to its fuzzy texture, it can easily irritate the throat, causing itchiness, coughing, and vomiting, hence it needs to be decocted in a bag.

I. Growth and Distribution

Growth Environment

Inula japonica thrives in warm, humid climates, and grows best in deep, loose, fertile, humus-rich sandy loam soils. It is not suitable for heavy clay or overly dry soils and should not be continuously cropped.

It has strong adaptability, heat and cold resistance, and a rapid growth rate. It is capable of self-propagation, and tolerates impoverished soils. It can be found on slopes, roadsides, moist grasslands, riverbanks, and field ridges at altitudes of 150-2400 meters.

Distribution Range

It is distributed in Mongolia, North Korea, Western Siberia in Russia, and Japan.

II. Morphology and Features

Inula japonica is a perennial herb with a short rhizome, horizontal or ascending, with somewhat robust fibrous roots.

Single stems, sometimes in clusters of 2-3, are erect, 30-70 cm high, sometimes with adventitious roots at the base, 3-10 mm in diameter, grooved, covered with long appressed hairs, or sometimes glabrous at the lower part. The upper part has ascending or spreading branches, all with leaves; internodes are 2-4 cm long.

Basal leaves are often smaller and wither during flowering; mid-leaves are oblong, oblong-lanceolate or lanceolate, 4-13 cm long, 1.5-3.5, rarely 4 cm wide, with somewhat narrow base, often with round semi-clasping small ears, sessile, apex slightly acute or gradually acute, margin with small pointed sparse teeth or entire, upper surface with sparse hairs or nearly glabrous, lower surface with sparse appressed hairs and glandular dots; midvein and side veins with denser long hairs; upper leaves gradually smaller, linear-lanceolate.

The head inflorescences are 3-4 cm in diameter, numerous or few arranged in loose umbel-shaped inflorescences; inflorescence stalks are slender.

Involucre is hemispherical, 13-17 mm in diameter, 7-8 mm long; involucral bracts are about 6 layers, linear-lanceolate, nearly equal in length, but the outermost layer is often leafy and longer; outer layer is leathery at the base, leafy at the upper part, with appressed hairs or nearly glabrous on the back, and ciliate; inner layer is membranous except for the green midvein, gradually acute, with glandular dots and cilia.

Ray flowers are yellow, 2-2.5 times longer than the involucre; ligules are linear, 10-13 mm long; tubular flower corollas are about 5 mm long, with triangular-lanceolate lobes; pappus is single layer, white with more than 20 slightly rough hairs, nearly equal in length to the tubular flowers.

Achenes are 1-1.2 mm long, cylindrical, with 10 grooves, truncate at the top, covered with sparse short hairs. Flowering period is from June to October, and fruiting period is from September to November.

III. Cultivation Methods

Selecting and Preparing the Land

Helichrysum bracteatum is not particular about soil types and can be planted on slopes, riverbanks, or beside ditches. However, it grows best in well-drained, fertile sandy loam or humus-rich soil. It prefers warm and humid climates.

After selecting the location, apply 3000-4000 kilograms of well-rotted manure or compost per acre as base fertilizer, deeply plow 20-25 centimeters, rake and level the soil, and create 1.2-meter-wide ridges.

Field Management

For seed propagation, thin out weak and overly dense seedlings when they reach 3-5 centimeters in height. When seedlings reach 5-10 centimeters, space them 15-20 centimeters apart. Fill in any gaps with new seedlings.

In May and July, and after rainfalls, perform intertillage weeding and fertilize, primarily using manure. After harvest, cultivate the soil. Water promptly during dry weather.

Loosen the soil after hot, dry periods or heavy rains to reduce water evaporation. Drainage is important during the rainy season.

IV. Propagation Methods

Propagation Conditions: Helichrysum bracteatum seeds are light-dependent and prefer fluctuating temperatures for germination. They do not germinate well at constant temperatures but thrive under fluctuating temperatures and light conditions in greenhouses.

The temperature range should be 7-25°C. When new seeds are stored in a paper bag at room temperature for a year, their germination rate is 5%, so seeds from previous years should not be used.

Seed Propagation: Create shallow furrows 30 centimeters apart, evenly scatter the seeds, cover with a thin layer of soil, and slightly compress. Cover the surface with straw or fallen leaves and water thoroughly to maintain soil moisture.

Seedlings should appear in about 20 days. After they sprout, remove the cover of straw or leaves, leaving a thin layer to keep the soil surface moist and prevent weed growth. Use 1.5-2 grams of seeds per acre. Start the seeding process 10-15 days earlier than direct seeding on sunny ridges.

Division Propagation: Use the offshoots from the mother plant’s root for propagation. Perform division propagation from mid-April to early May.

Dig holes with 30×15 centimeter spacing, remove the new plants growing next to the mother plant, and place them in the holes. Plant 2-3 seedlings per hole, spread the roots in the hole, cover with soil, and water thoroughly.

V.Pest and Disease Control

Although Helichrysum bracteatum is a perennial, some old roots may wilt or get diseased after 2-3 years of cultivation, so rotate the planting location. Root rot is common, especially during rainy seasons, so ensure good soil drainage.

After disease onset, use a 1000-fold dilution of a 50% carbendazim wettable powder or lime water (5 kilograms of lime in 100 kilograms of water).

VI. Value and Other Information

Source: The dried capitula of Helichrysum bracteatum or Helichrysum arenarium.

Taste and Meridians: Pungent, bitter, salty, and slightly warm. Pertains to the lung, spleen, stomach, and large intestine meridians.

Effects and Applications: ①Reduces phlegm and soothes cough and asthma. This herb is mildly warm and can be used to treat cough and asthma caused by cold or heat phlegm or external factors.

②Reduces nausea and vomiting. This herb is also good at reducing stomach gas, treating phlegm obstruction, and nausea and vomiting. It is often used with other herbs, such as mirabilite and Pinellia ternata.

Characteristics: This herb opens up with pungency, descends with bitterness, and warms and descends. It mainly enters the lung and stomach meridians.

It not only reduces phlegm and soothes asthma but also removes phlegm and water and relieves fullness, treating cough, asthma, and chest tightness caused by phlegm obstruction and lung qi reversal.

It also reduces stomach qi and relieves vomiting and belching, treating vomiting and belching caused by stomach qi reversal. It is an important medicine for treating lung and stomach qi reversal.

Usage and Dosage: Boil and drink, 3-9 grams, preferably decocted in a bag.

Precautions: This herb dispels heat, so people with yin deficiency, labor cough, or fluid injury and dry cough should not take it. Also, because this herb has fuzz, it can irritate the throat and cause coughing and vomiting, so it should be decocted in a bag.