Compared to other pines, singleleaf pinyon is unique in that it contains a single needle in each bundle. This pine provides both habitat and food for a variety of animals in desert ecosystems. Its wood is used for fence posts and as fuel for smelters and railroads; its pitch is used to waterproof pottery; and its pine nuts are eaten. This species can reach ages over 600 years old with the oldest known specimen being 888 years old. It is the most xeric pine in the United States.

Photo Credit: © Dawn Endico at Flickr via Wikimedia Commons.
Pinus monophylla
Common Name: singleleaf pinyon
Plant Functional Group: Pine
Class > Order > Family: Pinopsida > Pinales > Pinaceae
What does the species look like?

Singleleaf pinyon is an evergreen, conifer tree growing up to 40 feet tall, occasionally being multi-stemmed. Male and female cones are present on the same tree. The small, male cones bear pollen; the larger, female cones turn woody as they mature, which takes about three seasons. Pollination occurs by wind.

Singleleaf pinyon is found on arid rocky slopes, ridges, and alluvial fans. It often forms open woodlands. It is intolerant of shade and is drought tolerant.

Where is the species found?
States & Provinces
AZ, CA, ID, NM, NV, UT
Which phenophases should I observe?
Do you see...?
Needles Emerging needles
One or more emerging needles or needle bundles (fascicles) are visible on the plant. A needle or needle bundle is considered "emerging" once the green tip is visible along the newly developing stem (candle), but before the needles have begun to unfold and spread away at an angle from others in the bundle. For Pinus monophylla, the single needle is considered "emerging" until it has become twice as long as its brown papery sheath.
More...

How many needle bundles are emerging?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000

Young needles
One or more young, unfolded needles are visible on the plant. A needle is considered "young" and "unfolded" once it begins to spread away at an angle from other needles in the bundle (and is no longer pressed flat against them), but before it has reached full size or turned the darker green color or tougher texture of mature needles on the plant. For Pinus monophylla, a needle enters this phase once it has become twice as long as its brown papery sheath.

How many bundles with young needles are present?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000

Pollen cones Pollen cones
One or more fresh, male pollen cones (strobili) are visible on the plant. Cones have overlapping scales that are initially tightly closed, then spread apart to open the cone and release pollen. Include cones that are unopened or open, but do not include wilted or dried cones that have already released all of their pollen.
More...

How many fresh pollen cones are present?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000

Open pollen cones
One or more open, fresh, male pollen cones (strobili) are visible on the plant. Cones are considered "open" when the scales have spread apart to release pollen. Do not include wilted or dried cones that have already released all of their pollen.

What percentage of all fresh pollen cones (unopened plus open) on the plant are open?

  • Less than 5%
  • 5-24%
  • 25-49%
  • 50-74%
  • 75-94%
  • 95% or more

Pollen release
One or more male cones (strobili) on the plant release visible pollen grains when gently shaken or blown into your palm or onto a dark surface.
More...

How much pollen is released?

  • Little: Only a few grains are released.
  • Some: Many grains are released.
  • Lots: A layer of pollen covers your palm, or a cloud of pollen can be seen in the air when the wind blows

Seed cones Unripe seed cones
One or more unripe, female seed cones are visible on the plant. For Pinus monophylla, an unripe seed cone is green, pale yellow-brown or brown with scales closed together.
More...

How many seed cones are unripe?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000

Ripe seed cones
One or more ripe, female seed cones are visible on the plant. For Pinus monophylla, a seed cone is considered ripe when it has turned brown or gray-brown and the scales have begun to spread apart to expose the seeds inside. Do not include empty cones that have already dropped all of their seeds.
More...

How many seed cones are ripe?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000

Recent cone or seed drop
One or more seed cones or seeds have dropped or been removed from the plant since your last visit. Do not include empty seed cones that had long ago dropped all of their seeds but remained on the plant.
More...

How many seed cones have dropped seeds or have completely dropped or been removed from the plant since your last visit?

  • Less than 3
  • 3 to 10
  • 11 to 100
  • 101 to 1,000
  • 1,001 to 10,000
  • More than 10,000

What do these phenophases look like?

There is currently no photoguide available for this species. If you'd like help us create one, use the guidance document and species template provided here. Then send it via email to education@usanpn.org when it is complete.