Amorphophallus atroviridis

A dark-leaved tuberous aroid from central Thailand

Amorphophallus atroviridis is native to central Thailand, where it has been recorded in deciduous forest beneath bamboo and in dry deciduous dipterocarp forest at about 50–200 m. Its dark emerald-green to blackish-green leaflets have a pink-violet margin and often a bluish sheen.

A single divided leaf rises from an elongated, sometimes irregularly branching tuber during active growth. The leaf later dies back as the tuber enters dormancy below the surface, and a mature tuber may produce an inflorescence before the next leaf.

Care through active growth and dormancy

Watering

Begin watering Amorphophallus atroviridis regularly only after its shoot is extending and new roots are active. As the leaf naturally yellows, reduce water step by step and keep the dormant tuber much drier.

Temperature

A dormant dry tuber can be held a little cooler, but avoid cold conditions and all cold wet conditions.

Light

While Amorphophallus atroviridis carries its single leaf, place it close to an east window or a short distance from a brighter south or west window with hot midday rays filtered. A dormant tuber does not need light, but it should remain where temperature and moisture can be monitored.

Humidity and airflow

Ordinary household humidity can work for Amorphophallus atroviridis, while moderate to high humidity helps the divided leaf remain fresh and open without dry leaflet tips. Humidity is irrelevant to a dormant tuber and should never be used to keep its pot wet.

Fertilising

While the leaf is fully active and the pot is using water, apply a complete fertiliser at the low end of the product-label rate so the leaf can replenish the tuber. Stop feeding as the leaf begins to yellow or dormancy approaches.

Leaf care, seasonal care and watering

The leaf stalk of Amorphophallus atroviridis normally supports its umbrella-like blade. Do not cut a green leaf to force dormancy; let it yellow so resources return to the tuber, then remove the dry stalk at the base.

Problems and solutions for Amorphophallus atroviridis

• The single leaf yellows and collapses at the end of a growth cycle: Seasonal dieback is normal for this tuberous plant. Reduce watering as the leaf declines and keep the dormant tuber on the dry side; fresh growth will begin from the tuber rather than the old stalk.
• A mottled stalk carries a branched, umbrella-like leaf: That trunk-like leaf stalk supports a single divided leaf, and its natural blotching should not be scrubbed or treated. The plant commonly produces only one active leaf at a time.
• The tuber feels soft, wet or smells unpleasant: This is consistent with rot, not dormancy. Unpot it, cut away all discoloured tissue with a sterile blade, allow the wound to dry and reset only a firm clean tuber in fresh, sharply drained mix.
• No shoot appears for several weeks or months: A firm tuber may simply still be resting, so repeated watering can create the very rot you are trying to prevent. Keep it warm, check occasionally and increase water only after a shoot is clearly active.
• The leaf becomes finely speckled and dull: Inspect the many leaflet undersides for spider mites. Treat promptly and repeatedly, taking care not to snap the single stalk on which the season’s leaf depends.

Amorphophallus atroviridis is toxic to people and pets

• Keep this plant away from children, cats and dogs.
• Its leaves and stems contain insoluble calcium oxalate crystals, which can irritate the mouth, throat, skin and eyes.
• Chewing may cause burning pain, drooling, swelling, vomiting or difficulty swallowing. Contact a veterinarian or medical professional after exposure, especially if swelling or breathing problems occur.

When was Amorphophallus atroviridis first published, and what does it mean?

Amorphophallus combines Greek amorphos, misshapen, with phallos, phallus. The Latin epithet atroviridis means dark green.

Joseph Decaisne established the genus Amorphophallus in 1834 in Nouvelles Annales du Muséum d’Histoire Naturelle, volume 3, page 366; Carl Ludwig Blume had proposed the name.

Wilbert Leonard Anna Hetterscheid first described Amorphophallus atroviridis in 1994 in Blumea, volume 39, page 245.