(or possibly now Alocasia longiloba 'Watsoniana')
Alocasia watsoniana was known by me as a separate species, but recently botanists have grouped a whole lot of previously separate species together as part of the Alocasia longiloba complex. Alocasia watsoniana is one of these, and perhaps may now be more correctly known as Alocasia longiloba 'Watsoniana', and just another variety of the longiloba species.
It is distinctly different to the 'original' Alocasia longiloba. Its leaves are more rounded, and it has significantly more silver veining - although not as much as Alocasia longiloba 'Veitchii'. The large leaves can get to around 2 feet long and about the same wide, although I have read they can get as big as 3 feet long. The front of the leaves are dark green, with silver-white blade margins, midrib and primary veins. The backs of the leaves are eggplant purple.
It likes a reasonably shady spot (around 60 - 80% shade) in order to get the nice large leaves.
Alocasias require continual warmth and humidity. The soil should be rich but well drained, and the plant appreciates frequent watering (daily), especially as if grows larger. Note however, that when the plant is young and small, too much water (particularly if the weather is cold) will rot the tuber, so be careful not to overdo it.
At a glance:
Suitable for Zones: 10 - 12 (see my Zone Hardiness Map page)
Sun requirements: Full Sun to deep shade (up to 60-80% shade)
Moisture requirements: Moderate to high, well drained soil
Size when fully grown: 50cm to 1 metre (1-3 feet), similar spread wide
Not frost tolerant
Suitable as an indoor and container plant