Lucky bamboo, which is not a bamboo at all, is said to bring luck and is used extensively in feng shui. 
The number of stems given as a gift has significant meaning:
1- Simplicity.
2- Luck in Love & Marriage.
3- Happiness *Most popular as a gift.
4- Unlucky. Usually never given.
5- Full Life.
6- Prosperity.
7- Good Health.
8- Grow and Thrive.
9- All Around Good Luck.
10- Perfection.
21- Powerful Blessing.
 
Note: Sizes are measured from the bottom of the stalk to the top and does not include the height of the leaf. Each stem is sold separately.