There are very few trees in the grasslands of northern Arizona. Only on high mesa tops can the desert twins-pinon and juniper-be seen. Limited by lack of water, demanding seasons, high winds, trees must adapt in order to survive. Once established these plants are tenacious. Their roots will split rocks in search of nutrients, and many can live over 100 years. Large cottonwoods and willows are common in riparian areas.
The juniper is the classic arid-land tree. Its twisting, often-dead branches seem to epitomize the struggle of life with little water. When moisture is scarce, a juniper will actually stop the flow of fluids to some outer branches so that the tree has a better chance for survival. Scale-covered leaves and bluish, waxy-coated seeds help the tree conserve moisture. Indigenous people have used the bark for torches and as a tobacco substitute, wove it for cloth, and shredded it as an antibacterial diaper material.
Pinon pines often share spaces with junipers. Like juniper, pinons are very slow growing. Trees only four to six inches in diameter and ten feet tall may be 80 to 100 years old. Their root systems are extensive and often mirror the size of the above ground tree. Pinons produce compact cones that contain tasty, protein-rich seeds called pinenuts. Native people still rely on this tree as an important source of food. One pound of pinon nuts contains more than 3,000 calories. The tree also provided fuel, charcoal for painting, pollen for ceremonies. The resin or pitch was used for chewing gum, mending, cementing, and waterproofing. Many animals, such as groundsquirrels, also like the seeds for tasty and nutritious food.
Common to the washes and the Puerco River corridor are cottonwoods, willows, Russian olive and tamarisk. The latter two are non-native and, unfortunately, compromise the health of cottonwood and willow stands and the ecosystem that the native trees support.
The cottonwood tree takes its name from the small white fluffy seeds which, when they become airborne, can become quite thick in the air. The cottonwood tree can live to be over 100 years old, becoming one of the largest trees in North America-up to 100 ft. high with massive trunks over 5 ft. in diameter. They grow well in washes, even dry washes where the water table is easily reached by their roots. Cottonwoods are related to poplars and aspens, with which they share the same shaking, shimmering leaves.
Willows provide materials for indigenous artists for weaving beautiful baskets. They are also favorite places for many animals, particularly smaller song birds, to find shelter. During winter, their leafless branches can be a lovely shade of gold to orange to red along the many washes and Puerco River.
Shrubs and subshrubs are important members of the grassland communities. Both shrubs and trees provide shelter and food for many species of animals.
The most common shrubs in the park are saltbush and sagebrush. They both have grayish green leaves and can grow relatively large. Saltbush is still used by the Hopi as the source of a culinary ash they use in cooking. Sagebrush can be used as seasoning. Both are used for dye. One of the largest shrubs in the park is the cliffrose. During late spring into summer, the resinous evergreen leaves can disappear under a heavy bloom of creamy, fragrant flowers. Rabbitbrush is another attractive shrub with showy golden blossoms, a member of the same family as sunflowers and asters.