Arisaema rhizome (Arisaema heterophyllum) is an easy-to-grow ornamental species that is prized for its unusual Jack-in-the-pulpit flowers. This is a shade-loving forest plant that thrives in parts of the garden that receive only partial sunlight. This plant is especially prized as an ornamental species in Japan.
I. Appearance and Characteristics
Arisaema heterophyllum, the dancing crane cobra lily, belongs to the monocotyledonous flowering family Araceae.
The roots are tubular, depressed globose shaped, and around 2–6 cm in diameter. The usually solitary leaves are around 30–60 cm long, with glaucous petioles and sheathing adjacent to the pseudostem. They are sedately divided, adaxially dull green and abaxially pale green, and contain 4 or 5 cataphylls and multiple leaflets, ranging from 11 to 21 in number. The central leaflet is 3–15 cm long and 0.7-5.8 cm wide; the outermost leaflets are smaller. The distance between leaflets is around 0.5–5 cm. The leaves have a variety of shapes, such as oblanceolate, oblong, linear-oblong, base cuneate, and apex cuneate.
The peduncle of the flower is around 50–80 cm long, and is usually longer than the petiole. The flower also has a spathe tube that is cylindrical, 3.2–8 cm long, 1-2.5 cm wide, outside glaucous, inside whitish green, and its throat is slightly recurved. The spadix of the flower is either bisexual or monoecious and male. In the female part of the bisexual spadix it has a punctate stigma, a distinct style, and a globose ovary that contains 3 to 4 ovules; the male part contains sterile flowers. The anthers of the male spadix has thecae dehiscing by the apical slits.
The pale white sigmoid appendix is 20 cm long, ascending, and gradually tapers from the sessile base to sharp apex. The flowering period usually starts in April or May, and continues from July to September. The fruits are cylindrical yellowish red or red berries that usually have 1 seed.
The plant contains Arisaema heterophyllum agglutinin (AHA), a substance that can cause blood particles to coagulate and aggregate. It was revealed that AHA had negative effects towards the feeding behaviour of the Indian Grain Aphid (Sitobion miscanthi), causing the aphids’ lifespan to reduce significantly. Resistance towards Indian Grain Aphids in wheats was observed to have improved after intruding AHA to the plants.
Arisaema heterophyllum is native to East Asia, including China, Inner Mongolia, Japan, and Korea. In China, it is grown across different provinces except for the Northwest region and Tibet. In Japan, it is grown in Honshu and Kyushu.
The species tends to grow in evergreen and deciduous riparian forests, shrublands, wetlands (inland) or grassland where shade is available and moisture is retained. It is closely associated with flood plains and prefers humus-rich and well-draining soil. The tuber is intolerant to low temperatures. In Japan, it is considered a threatened species due to the loss of riparian forest along the major rivers of Kanto Plain.
II. How to Grow and Care
Sunlight and Soil
Arisaema rhizome performs best in moist, well-draining soil and providing dappled shade to protect from harsh sunlight. Due to their specific soil moisture needs and sensitivity to light
Watering
Native to shaded, moist areas, arisaema rhizome thrives in environments that mimic the consistent moisture of its natural habitat. This species exhibits a preference for evenly moist soil and demonstrates moderate drought tolerance. For optimal health, watering every week is recommended to maintain its preferred moisture levels. Given its inclination for humid conditions, arisaema rhizome is more commonly grown outdoors where it can benefit from natural rainfall patterns. Its growth cycle aligns closely with water availability, making it a prime candidate for gardeners who can provide regular watering without over-saturation.
Fertilizing
To foster vigorous growth and inflorescence in arisaema rhizomes, apply a balanced fertilizer monthly during the growing season, tapering off in autumn. For reproductive success, opt for high phosphorus types pre-bloom. Use fertilizers sparingly, over-fertilization risks arisaema rhizome’s health. During dormancy, cease fertilizing. Novices should start with half-strength recommendations, observing the arisaema rhizome’s response.
Propagation
Arisaema rhizome belongs to a group of perennial plants known for their intriguing shapes and variable foliage. Propagation of arisaema rhizomes is primarily achieved through sowing seeds. To optimize results, fresh seeds should be sown in a well-draining substrate that maintains consistent moisture without becoming waterlogged.
The use of a specialized mix that mimics arisaema rhizome’s native soil can encourage better root development. Providing a stable environment with indirect sunlight will support gradual growth. Patience is key as arisaema rhizome can take several years to mature from seed to full plant.
Transplanting
Transplant arisaema rhizome when warmth returns and growth resumes, typically during the post-vernal awakening, to ensure root establishment. Opt for partial shade locations with moist, well-draining soil and handle with care to protect the delicate rhizome.
III. Uses and Benefits
The rhizome is often used in Chinese traditional medicine as a treatment for coughs, epilepsy, and tetanus. It is prepared using ginger and potassium aluminum sulphate for purifying purposes.
