Echinodorus martii (sometimes known as Echnidorus major) is a popular aquarium plant where it's been available for years so you could say it's tried and tested! Very easy to grow and great for beginners.
A medium sized aquatic plant with light green leaves, it's a heavy root feeder so make sure its planted in nutrient rich substate and use root tabs. This plant doesn't need pressurised CO2 to flourish but it will always help. Like all Echinodorus, it can grow to a decent size so remove larger leaves to keep it in a sensible size. In a well lit aquarium this plant will definitely be a centre piece and will look truly fabulous.
Can grow up to 60cm but normally about 30cm.