Scientific name: Pinus monophylla J.Torrey & Frémont 1845
Synonyms:Caryopitys monophylla (Torr. & Frém.) Rydb., Pinus californiarum D.K.Bailey, Pinus edulis var. monophylla (Torr. & Frém.) Torr., Pinus fallax (Little) Businský, Pinus fremontiana Endl.
Common names: One-leaved nut pine, Single leaf pinyon
Description
Tree to 10(-20) m tall, with trunk to 0.5(-1.3) m in diameter, but often dividing into several trunks at or near the base. Bark grayish brown, dividing into wavy, narrow ridges separated by shallow furrows. Crown egg-shaped, becoming more dome-shaped and open with age, with numerous upwardly angled branches from near the base densely clothed with foliage near the ends. Twigs yellowish brown to reddish brown, hairless or slightly hairy at first, becoming gray and hairless with age. Buds 5-10(-15) mm long, resinous. Needles in bundles of one (or two), each needle (2-)4-6 cm long, very stiff and prickly, straightly curved, lasting 4-8(-10) years, dull grayish green to dark green. Individual needles with lines of stomates all around, an undivided midvein, and (2-)4-12(-23) small to modest-sized resin canals. Sheath 5-11 mm long, curling back and soon shed. Pollen cones 7-10 mm long, reddish purple. Seed cones (4-)5-7(-8) cm long, egg-shaped to roughly spherical, with (15-)25-60 seed scales, green before maturity, ripening orange-brown, opening widely to release the seeds and then falling with the 0.5-1 cm long stalk. Seed scales paddle-shaped, with deep seed cavities, the diamond-shaped exposed portion rising pyramidlike on the face and ending in a large diamond-shaped umbo sometimes bearing a short, weak prickle. Seed body 13-18 mm long, the shell 0.3-0.5 mm thick, unwinged or with a rudimentary wing remaining attached to the scale.
Basin and Range region of southwestern North America from south-central Idaho and east-central California to southwestern New Mexico and northern Baja California (Mexico). Forming pure stands or mixed with junipers and sometimes shrubby oaks in open pinyon-juniper woodlands in an elevational band overlapping with chaparral or sagebrush scrub below and montane pine forests above; (950-)1,200-1,600(-2,300) m.
Conservation Status
Red List Category & Criteria: Least Concern
(Pinus monophylla's great extent of occurrence is far beyond any threshold for a threatened category. The area of occupancy might be more limited as it can be sparse in some areas, but it is abundant in other locations. As there is no evidence of substantial decline, an assessment of Least Concern is warranted)
References
Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland
Copyright © Aljos Farjon, James E. Eckenwalder, IUCN, Conifers Garden. All rights reserved.
Rootstock: Pinus wallichiana
