Giant Taro

Giant taro (Alocasia macrorrhizos), called pidalu in southern Pakistan to distinguish it from common arvi, is the towering arum that converts a damp, partly shaded corner of the food forest into a high-biomass food and medicine plant. POWO records its native range from Central Malesia to Queensland,¹ and on the Sindh coast and lower KPK valleys it grows tall enough to read as a small tree.

Where it thrives

Giant taro is a sub-shrubby aroid of higher-rainfall lowland tropics, growing up to about 1,000 m elevation. Optimum daytime temperatures sit in the 20 to 25 degree band, though the plant tolerates a 10 to 32 degree range,² which suits the warmer Sindh coast and frost-free pockets of the lower KPK hills. Missouri Botanical Garden notes it as winter hardy to USDA zones 9 to 11 and recommends part shade or filtered sun, moist to wet organically rich soils, and a sheltered position out of strong wind that will tear the huge leaves.³ Full sun in mid-summer causes leaf scorch on the Punjab plains, so site it on the east or north side of a taller canopy plant.

Role in the system

Giant taro fills the upper groundcover stratum as a clumping, tall-leaved understory anchor. The leaves can reach 3 to 4 feet across on petioles up to 12 to 15 feet tall,³ so a small clump produces serious shade and biomass for chop-and-drop mulch. It pairs naturally under banana or papaya in a Sindh-coast guild, taking the dappled light those crops drop and contributing its own mulch back to the bed.

Growing it

Propagate from corm offsets or basal suckers in spring; seed is impractical because cultivated plants rarely fruit.³ Plant offsets in deep, well-rotted compost about 60 cm apart, water deeply through the warm months, and chop senescent leaves back to the petiole base for mulch as they brown. The clump expands outward year on year and can be lifted and divided every three to four seasons. Where winter dips below 5 degrees on the Pothohar plateau, lift small corms and overwinter in a frost-free shed; on the Sindh coast no winter management is needed.

What you get

Cooked corm flesh and tender shoots — but only after thorough processing. Every part contains calcium oxalate raphides that cause severe oral and skin irritation when raw; long boiling, baking or fermenting destroys the irritant and unlocks a dense package of starch, dietary fibre, calcium, iron and potassium.² Traditional medicine across South Asia uses processed corm and leaf preparations for inflammation, cough and digestive complaints, with modern reviews documenting flavonoid, alkaloid and saponin activity behind those uses.²

Sourcing notes

Source offsets from an established Karachi or Hyderabad ornamental nursery — the plant is sold for its bold foliage long before it is grown for food. Site it under a banana or papaya overstorey on a moist, sheltered bed and keep it well away from children’s beds, since the raw stalk can blister skin on contact. Pair the clump with watercress at any clean trickle of water nearby, and with small ginger or turmeric in the same shade pocket.

Sources

1. Royal Botanic Gardens, Kew (2024). “Alocasia macrorrhizos (L.) G.Don.” Plants of the World Online.
2. Das, O., Nickhil, C. & Deka, S.C. (2026). “A comprehensive review on the nutritional value, anti-nutritional factors, acridity, medicinal properties, and culinary applications of Alocasia macrorrhizos.” Sustainable Food Technology (Royal Society of Chemistry).
3. Missouri Botanical Garden (2024). “Alocasia macrorrhizos.” Missouri Botanical Garden Plant Finder.