Wetlands form California to Texas and from Colorado to Mexico are home to this riparian tree. Unlike numerous other riparian trees which can regenerate by sprouting, fremont cottonwood is an obligate seeder. But this pioneer species compensated for this characteristic by producing seed in abundance. It has also given the tree a nasty reputation for making a mess, and is therefore illegal to grow in certain communities. Seeds are released during the time of spring floods, as floods are crucial for seed dispersal and establishment.
Establishment depends on moist alluvium provided by floods.
Surface moisture must persist until the roots are deep enough to obtain the constant underground moisture found in a natural riverbed. The upper surface of the soil dries rapidly in the summer, so cottonwood seedling roots must grow rapidly to escape death by desiccation. With deep roots, seedlings can survive through the summer. But summers heat also drops the level of the water table. A constant supply of water is required not only as a seedling, but throughout the life of the tree.