American agave, century plant
Far south Arizona and south Texas. Also naturalized in parts of coastal California
Large rosettes, sometimes with a short stem. Readily forms clusters via basal shoots
Scrubland, sandy soils
Yellow, in clusters along lateral branches sprouting from the upper half of the 15 to 30 foot tall stalk
Although native to Mexico, and in the US growing wild in a just a few southerly locations in Arizona and Texas, agave americana is commonly used as a landscaping plant, since it is one of the largest and fastest growing of all agaves, producing a rosette 12 feet wide, with green or greyish leaves (sometimes with banded colors) up to 6 feet long. Like most agave, these are lined by sharp teeth, each about 1/3 inch long and an inch or less apart. In mature specimens some leaves curl backwards, resulting in a less symmetric plant.
There are a number of cultivated, smaller-growing varieties which have white or yellow stripes along the edges or the middle of each leaf, and also two sub species (Americana and Protamericana). The plant is found in a few locations in south Arizona, but it is believed these are not native; the only indigenous populations are in Starr County, south Texas.