This post is a work in progress. Like my other identification “guides”, this is a tool for my learning as much as it is an attempt to provide education. If you find errors or the opportunity to enhance the guide, I would appreciate feedback through comments or messages.

• Pinus description in iNaturalist
• Pinus observations in the Greater Yellowstone Ecosystem
• BONAP Ranges

Members of the pine family can be most easily distinguished to genus Pinus by noting the needles. Pinus (pine) needles grow in bunches (fascicles) of 2 or more needles. Noting the number of needles in the cluster helps to narrow down the options for species. In the Greater Yellowstone Ecosystem (GYE), this alone can allow you to narrow to either Trifoliae - American Hard Pines or Quinquefoliae - White Pines (I have also seen people use Strobus, which is the same group plus Pinyons). Seed (larger woody) and pollen (smaller, sponges) cones are also beneficial for identifying to species. Note presence/absence of cones as well as color, length, shape, and (for seed cones) texture. Make sure to check high in the tree for seed cones. Sometimes a distant picture can show relative size and color. If you took a wide angle shot and you can zoom in on the cones or needles, consider adding both the original and a cropped version to iNat. iNat compresses pictures, so the cropped one might enable an ID. A useful resource is the Gymnosperm Database, maintained by an iNat user. Tree shape and bark can also be useful characters, but tend to be more age dependent.

Section Trifoliae - American Hard Pines (2 needles, maybe 3)

Pinus contorta - Lodgepole Pine

Photo 1 Source, Photo 2 Source

• Range - Present in all counties of the GYE except Caribou, ID
• Identification Resources: FNA, Gymnosperm Database, Montana Field Guide, AZ Lodgepole vs Ponderosa, USFS, Key to Conifer trees of Wyoming, Forests of Yellowstone, JH Wildlife
• 2 needles per fascicle, 1-3 inches long (vs 5- 10 inches on ponderosa). Needles can be twisted/spiraled and are green to yellow green. Orange-red pollen cones. Seed cones prickly, 1-2 inches long; asymmetrical, lanceoloid/conical to ovoid before opening, broadly ovoid to globose when open. Bark is usually described as thin and scaly, but thickness can vary, with higher elevation trees having thinner bark. Sometimes tall with small diameter. Can dominate forests after repeated fires. Dominant tree in Yellowstone, comprising 80% of the canopy.

Pinus ponderosa

Photo 1 Source, Photo 2 Source

• Range - Not common within the Greater Yellowstone Ecosystem. Present in WY counties: Park, Fremont, Lincoln. Present in MT counties: Beaverhead, Madison, Gallatin, Carbon. Not present in Teton WY, Sublette WY, Park MT and the Idaho Counties in the GYE.
• Identification Resources: FNA, Gymnosperm Database, Montana Field Guide, AZ Lodgepole vs Ponderosa, USFS, Key to Conifer trees of Wyoming, Bryce NPS
• 2 needles per fascicle in the scopulorum variety of the rocky mountain region (3 in the western variety). Yellow-green to blue-green needles are longer than contorta (3.5 - 5.75 in). Further west, Ponderosa needles are generally 5-10 inches long. Needles can appear tufted or foxtail-like. Pollen cones are dark red, brown red, or purplish red. Bark in fractured plates that resemble a jigsaw puzzle. Bark of mature trees can smell like vanilla and is reddish or orangish. Can grow very tall. Consider when seeing longer needles and growth patterns on branches that look different from typical lodgepole.

Section Quinquefoliae - White Pines (5 needles)

Pinus albicaulis - Whitebark Pine (endangered species)

Photo 1 Source, Photo 2 Source

• Tracked on iNat through the The Whitebark Pine Project. The related website contains additional information.
• Range- Present in most counties of the GYE. Rare in Wyoming and Idaho Counties
• Identification Resources: The Gymnosperm Database - has a good list of characters to distinguish from Limber and Western White Pine, NW Conifers, JH Wildlife, Identification guide for 5 needle pines, Photo of whitebark and limber pine cones side by side.
• Research Grade albicaulis in the GYE, Research Grade albicualis with cones (requires cones shown? observation field), Observation with nice discussion, Clark’s Nutcracker eating whitebark pine seeds
• Additional representative photos from the whitebark pine project
• High elevation tree with round or irregular crown. 5 needles per bundle, shorter needles than the Western White Pine. Purple cones turn brown as they mature are only 2-3 inches long (smaller than limber pine). However, the cones are rarely seen. They produce large seeds and are a favorite food source of the Clark’s Nutcracker. Absence of cones on the ground is more supportive of Whitebark pine than Limber pine. Pollen cones are a vibrant scarlet and frequently can be found at a height for easy photography. Young trees are likely to grown in multi-stem bunches. These are separate trees and generally only one survives to older age.

Pinus flexilis - Limber Pine

Photo 1 Source, Photo 2 Source

• Range - Present through out the GYE, but listed as rare in Wyoming.
• Identification Resources: Gymnosperm Database, NW Conifers, Identification guide for 5 needle pines, JH Wildlife
• 5 needle pine that can be confused with whitebark pine. Pine cones are 3-7 inches long. They start out as green and mature to brown. Large, whole cones on the ground are usually an indication of Limber Pine (as opposed to Whitebark). Pollen cones are often yellow/amber, but can be red.
• Interesting observations: Assume flexilis at Mammoth

Pinus monticola - Western white pine

Photo 1 Source, Photo 2 Source

• Range - only Gallatin County, MT in the GYE
• Identification Resources: Gymnosperm Database,NW Conifers
• 5 needles per fascicle, bluish colors. Loose fascicles results in the need for close inspection to count needles in the bundle (both Limber and Whitebark have tighter bundles of needles). Cones are long with a banana-like curve. Pollen cones are long and yellow. Large trees have rectangle to hexagonal plates of bark. Crown is a narrowly conical. Grows at lower elevations than limber and whitebark.

Identification Workflows

• Pines that Need ID in the Greater Yellowstone Ecosystem

Posted on January 22, 2023 04:29 PM by whitneybrook