The Pony Tail Palm (Nolina recurvata) is not really a palm tree species at all. It is one of several "palm-like" plants that have been given names that include the term palm because they have an appearance that is similar to that of a palm. Other pseudo palms include the Madagascar palm, the Giant Bird of Paradise, Fern Palm and the Cycas Revoluta.
The Pony Tail palm is commonly used as a potted plant for both indoor and outdoor settings.
One of the more striking features of the Pony Tail palm is its large, round, bulb-like base that can reach a diameter of more than five feet at its widest point. Notice that even this relatively small one in the picture above has bulged so much at the base that it has broken the concrete container that it was planted in.
The leaves of the Ponytail palm grow at the terminal ends of the "branches". They are long and tapered to a point and arranged in a rosette type cluster the can resemble a head of hair or a cluster of feathers like some chickens have. If you find my descriptions confusing just go by the pictures and make your own call on what they look like.
I tried to capture a picture of the flower of this species but I think that the plant below was just past the prime floral stage. Not only that, my picture did not turn out very clear. I´ll have to keep an eye out for another one in flower.
The image below, taken in the University of Malaga botanical garden, shows what this plant looks like when it reaches full maturity with multiple branches and a more proportionate distribution between the base and the trunk.