These evergreen shrubs are native to the dessert regions of America, and will appeal to those who enjoy plants with an architectural and exotic appearance. They are characterised by their rosettes of sword-like leaves which form a head at the base or tip of the branches or trunks. In the summer long stems emerge from the centre of the rosettes and carry clusters of creamy-white bell-shaped flowers. They will thrive in any soil that is permeable and not compacted and should be watered sparingly if grown in a container. Protection from cold winds is essential so position in a sheltered full-sun position or cultivate as cool conservatory subject.