Common name: hornwort
Scientific name: ceratophyllum demersum (The Complete Idiot's guide to Freshwater Aquariums by Mike Wickham, Alpha books 1998)
Origin: native to North America
Planting zone: floating plant, doesn't grow roots.
Fertilizers: not necessary
Growth rate: very fast
Size: several feet long
Lighting:low to moderate
Sold as: bunch plant
Hornwort is a very popular plant in the aquarium trade. It has very fine, soft needle-like leaves bound close together in a circular pattern. Hornwort is very inexpensive, grows quickly, and is rather undemanding. It's an extremely versatile aquarium plant. Many people use it as a spawning mop for killifish and as a hiding place for livebearer fry.
Although it's a great beginner's plant, hornwort does have a couple of downfalls. When introduced to a tank containing aquarium salt, hornwort will shed all its needles and make a huge mess in your aquarium.
Overall hornwort is a great, fasting growing, versatile, and undemanding aquarium plant that's perfectly suited to the beginner aquarist.