Trees and Shrubs

tree grows out of petrified wood log
Plants make use of soil pockets, even those collected within broken petrified wood pieces.

NPS/Marge Post


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.

Common Trees, Shrubs, and Subshrubs of Petrified Forest National Park

Juniperus monosperma (Engelm.) Sarg. one seed juniper
Juniperus osteosperma (Torr.) little Utah juniper

Ephedra nevadensis S. Wats. Nevada jointfir
Ephedra torreyana S. Wats. Torrey's jointfir
Ephedra viridis Coville Mormon tea

Pinus edulis Engelm. twoneedle pinyon, pinyon pine

Yucca angustissima var. angustissima Engelm. ex Trel. fineleaf yucca, narrow-leaved yucca
Yucca baccata Torr. banana yucca

Rhus trilobata Nutt. skunkbush sumac

Artemisia bigelovii Gray Bigelow's sage
Artemisia filifolia Torr. sand sagebrush
Artemisia frigida Willd. prairie sagewort
Artemisia ludoviciana Nutt. white sagebrush
Artemisia tridentata Nutt. big sagebrush, common sagebrush
Baccharis wrightii Gray Wright's baccharis
Brickellia californica (Torr. & Gray) Gray California brickellbush
Brickellia eupatorioides var. chlorolepis (Woot. & Standl.) B.L. Turner false boneset
Brickellia oblongifolia var. linifolia (D.C. Eat.) B.L. Robins narrowleaf brickllebrush, Mohave brickllebrush
Chrysothamnus greenei (Gray) Greene Greene's rabbitbrush
Chrysothamnus pulchellus (Gray) Greene southwestern rabbitbrush
Chrysothamnus viscidiflorus (Hook.) Nutt. yellow rabbitbrush
Ericameria nauseosa ssp. nauseosa var. (Pallas ex Pursh) nauseosa Nesom & Baird rubber rabbitbrush
Ericameria parryi var. nevadensis (Gray) Nesom & Baird heathgoldenrod, Parry rabbitbrush
Gutierrezia microcephala (DC.) Gray threadleaf snakeweed
Gutierrezia sarothrae (Pursh) Britt. & Rusby broom snakeweed
Heterotheca villosa var. villosa (Pursh) Shinners hairy false goldenaster
Hymenoxys richardsonii var. floribunda (Gray) Parker Colorado rubberweed
Isocoma drummondii (Torr. & Gray) Greene Drummond's goldenbush
Iva acerosa (Nutt.) R.C. Jackson copperweed
Machaeranthera grindelioides var. (Nutt.) grindelioides Shinners rayless tansyaster, gumweed aster
Machaeranthera pinnatifida ssp. (Hook.) pinnatifida Shinners tansyleaf tansyaster
Petradoria pumila (Nutt.) Greene grassy rockgoldenrod
Picradeniopsis woodhousei (A. Gray) Rydb. Woodhouse's bahia
Psilostrophe tagetina (Nutt.) Greene woolly paperflower
Psilostrophe sparsiflora (Gray) A. Nels greenstem paperflower
Senecio flaccidus var. douglasii Less. (DC.) B.L. Turner & T.M. Barkl. Douglas' ragwort, groundsel
Senecio flaccidus var. flaccidus Less. threadleaf groundsel
Senecio spartioides var. multicapitatus (Green M. ex Rydb.) Welsh broomlike ragwort
Tetradymia canescens DC. spineless horsebrush

Mahonia haematocarpa (Woot.) Fedde red barberry, algerita, red Oregon-grape

Lepidium montanum var. glabrum C. L. Hitchc. mountain pepperweed

Arenaria eastwoodiae var. adenophora Kearney & Peebles Eastwood's sandwort

Allenrolfea occidentalis (S. Wats.) Kuntze iodinebush
Atriplex canescens (Pursh) Nutt. fourwing saltbush
Atriplex confertifolia (Torr. & Frem.) S. Wats.shadescale saltbush
Atriplex obovata Moq. mound saltbush
Bassia americana (S. Watson) A.J. Scott [Kochia americana] greenmolly
Krascheninnikovia lanata (Pursh) Guldenstaedt winterfat
Sarcobatus vermiculatus (Hook.) Torr. greasewood
Suaeda moquinii (Torr.) Greene Mojave seablite
Zuckia brandegeei var. arizonica (Standl.) Welsh Arizona siltbush
Zuckia brandegeei var. brandegeei (Gray) Welsh & Stutz siltbush
ex Welsh

Elaeagnus angustifolia* L. Russian olive

Alhagi maurorum* Medik. camelthorn
Astragalus albulus Woot. & Standl. cibola milkvetch
Astragalus brandegeei Porter Brandegee's milkvetch
Astragalus kentrophyta var. elatus Gray spiny milkvetch
Caesalpinia jamesii (Torr. & Gray) Fisher James' holdback
Parryella filifolia Tott. & Gray ex Gray common dunebroom

Marrubium vulgare* L. horehound
Poliomintha incana (Torr.) Gray hoary rosemarymint, frosted mint
Salvia pachyphylla Epling ex Munz blue sage

Mirabilis linearis var. linearis (Pursh) Heimerl narrowleaf four o'clock
Mirabilis multiflora (Torr.) Gray Colorado four o' clock, large four o' clock

Forestiera pubescens var. pubescens Nutt. stretchberry, desert olive
Menodora scabra Engelm. ex Gray rough menodora

Calylophus lavandulifolius (Torr. & Gray) Raven lavenderleaf sundrops
Oenothera caespitosa ssp. caespitosa Nutt. tufted eveningprimrose
Oenothera caespitosa ssp. crinita (Rydb.) Munz tufted eveningprimrose, morning-lily

Eriogonum alatum var. alatum Torr. winged buckwheat
Eriogonum corymbosum var. aureum (M.E. Jones) Reveal crispleaf buckwheat, corymb buckwheat
Eriogonum ericifolium var. pulchrum (Eastw.) Reveal Yavapi County buckwheat
Eriogonum jamesii var. jamesii Benth. Jame's buckwheat
Eriogonum lachnogynum Torr. ex Benth. woollycup buckwheat
Eriogonum leptocladon var. ramosissimum T. & G. sand buckwheat
Eriogonum leptophyllum (Torr. & Gray) Woot. & Standl. slenderleaf buckwheat
Eriogonum microthecum Nutt. slender buckwheat

Purshia stansburiana (Torr.) Henrickson Stansbury cliffrose

Populus angustifolia James narrowleaf cottonwood
Populus deltoides ssp. wislizeni Bartr. ex Marsh. (S. Wats.) Fremont cottonwood, guerigo, alamo
Populus fremontii S. Wats. Fremont cottonwood
Populus ×acuminata Rydb. (pro sp.) [angustifolia × deltoides] lanceleaf cottonwood
Salix exigua Nutt. narrow leaf willow, coyote willow
Salix gooddingii Ball Goodding's willow

Ailanthus altissima* (P. Mill.) Swingle tree-of-heaven

Tamarix chinensis* Lour. fivestamen tamarix, saltcedar

Ulmus pumila* L. Siberian elm

Last updated: March 21, 2016

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Petrified Forest, AZ 86028


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