Xanthosoma mafaffa

Schott 1855

It is similar to X. atrovirens, but the shape of the juvenile leaves is sagittate, not cordate.

photo (1-2) - Botanic Garden CZRB PAN Warsaw, (3-4) - Botanic Garden Wroclaw, Poland; © Bartosz T. Zalewski, 2005
The blackish petioles indicate it is the "Morado" form, commonly eaten in Costa Rica and other Central American countries.

The IAS: Xanthosoma mafaffa Tropicos: Xanthosoma mafaffa