Limber Pine

Basic Information
Tree ID: 
157
Family: 
Pinus
Genus and species: 
Flexilis
Description: 
The Limber Pine, of the family Pinaceae and the genus Pinus, is an evergreen gymnosperm native to the Rocky Mountains of Western U.S. and Canada. Limber pines range from 7-12 m in height and 60-90 cm in diameter; they have needle-shaped, dark-green leaves, light-gray bark that becomes red-brown with age, and resinous, flexible branches. They thrive in subalpine habitats (10,000 to 11,500 feet in elevation), but are remarkably adaptable due to their tolerance to cold and drought. They are monoecious, with clustered yellow-brown staminate cones and woody, deep-brown ovulate cones that give rise to winged seeds. The seeds (pine nuts) and inner bark of Limber Pines are food sources for various animals, most notably nutcrackers and squirrels, who in turn aid in seed distribution. The branches of the Limber Pines also serve as a habitat for various animals and rodents, providing protection from predators and adverse weather conditions. Limber Pines can take several hundred years to reach maturity and can live for over 1000 years. Though Limber Pines are evergreen, fertilization of ovulate cones only occurs in late spring, and seed dispersal mainly occurs in the fall. Though Limber Pine wood is not suitable for commercial timber harvesting, its timber has been used for cabins, fencing, mining, and firewood. Limber Pines bear pine nuts, which have a wide variety of culinary applications in foods like pesto, salads, granola, and various baked goods. Not factoring in human activity, the greatest risk to Limber Pine populations is disease: both white pine blister rust (a common fungal disease in pines) and dwarf mistletoe (Arceuthobium Cyanocarpum) are leading causes of Limber Pine mortality.
Surveyors: 
Will Caraccio, Sem Asmelash, and Michael Hernandez
Location
Area: 
Marsh and Farnam Gardens
Collected Data
Tree shape: 
Pyramidal
Date of tree entry: 
02/07/2024
Height: 
7.60 m
Diameter at breast height: 
0.14 m

Bark
Light gray bark in immature Limber Pines becomes dark brown with age and splits into scaly plates and ridges. The bark is heavily creased, contains sap stains, and is weakly attached to the trunk.
Twigs & branches
Twigs are pale red-brown, slightly resinous, and very flexible. Buds are red-brown and ovoid. Needle-shaped leaves cluster at the ends of each branch.
Foilage
The Limber Pine has needle-like leaves that are pliant, waxy, and dark-green. There are 5 needles per fascicle, each needle persisting 5-6 years.
Reproductive Structures
Ovulate cones are moderately sized compared to other pine species. Typically range 6-12 cm in length. They have an elongated oval shape to them. Younger ovulate cones are initially a green color, but as they mature they transition to a deep brown color. This change in color aligns with maturation of the cone before seed dispersal. The ovulate cones have a woody texture with overlapping scales throughout and are very sturdy. Mature cones have resin on the ends of each scale. Staminate cones are broadly cylindrical, clustered, and are pale red or yellow.
Fruit
No fruit.
Seasons
  • Spring
Research
Natural range of distribution: 
Habitat: 
The natural range of limber pine generally is from Alberta and southeastern British Columbia to New Mexico, Arizona, and eastern California. Limber Pine thrive in subalpine life zones--the transition zone between the montane and alpine regions found between 10,000 and 11,500 feet of elevation. This tree grows best when exposed to full sunlight or partial shade. It prefers moist or dry conditions, but can effectively adapt to wet and cold conditions. It adapts to wet soil conditions by reducing the length of its root system. It is one of the most tolerant species of cold and windy environments. It is also very tolerant of drought conditions--its thick cuticle and low surface-area needles are adapted to reduce water loss through evaporation.
Origin, history, and uses: 

Origin and Evolutionary history/phylogeny

  • Pinus originated approximately 150 million years ago in the mid-Mesozoic era.
  • Cline: In ecology, a cline is a gradual change in a species’ biological traits across its geographical range. Pinus flexilis forms a cline with another closely related pine species, called Pinus strobiformis. This means that in between the two geographic ranges of P. flexilis and P. strobiformis there are pine populations that are genetic intermediates of these two species. Intermediate populations occur from southern Colorado to the northern Sierra Madre—these intermediates are called Pinus reflexa, or often are referred to as subspecies of P. flexilis or P. strobiformis. 

Common Uses:

  • It was previously used as support structures in mining applications and railroad development. Pine nuts found in pine cones are not commonly used for culinary applications but they are edible and can be used in foods like pesto, pasta, granola, salads, and baked goods.
  • Can provide useful timber for cabins, fencing, mining, and firewood. Nowadays it is not used commercially as a timber source because its trees are too small and its wood is resinous and often contorted.
Phenology: 
It can take pine trees several hundred years to reach maturity. Mature trees can live for over 1000 years. Pine cones develop and ripen between august and september, and seeds are released from september through october. Seeds are not effectively dispersed through the wind, and instead rely on birds and rodents. Both male and female flowers are found within the same tree (monoecious). The male reproductive organ is a reddish cone like structure, while the female reproductive organ is a woody cone. The male cones release pollen through the wind and travel to female cones to fertilize the ovules. After fertilization, embryos develop in woody sporophyte encasings called seeds. These seeds are extracted by various animals, such as birds and rodents, and are distributed throughout the ecosystem. Seed dispersal mainly occurs in the fall, and Limber Pines enter a dormant period in the winter.
References: 

“Limber Pine” https://mortonarb.org/plant-and-protect/trees-and-plants/limber-pine/ 

“Limber Pine/Rocky Mountain White Pine” https://www.lamtree.com/limber-pine/ 

“The Gymnosperm Database: Pinus Flexilis” https://www.conifers.org/pi/Pinus_flexilis.php 

More
Other information of interest: 

Ethnobotany:

  • The Limber Pine has been growing in the Great Basin of the United States for hundreds of years. As such, there is strong archaeological evidence that it was used in the past by native Great Basin tribes, such as the northern Shoshone. It might also have been used as a food source (pine nuts) by ancient peoples of the Alta Toquima Village in Nevada.

Etymology:

  • Flexilis and the colloquial name “limber” both reference the branches, which are tough and flexible

 

Extraordinary specimens:

  • One of the oldest limber pines is in Alberta, Canada. It has a girth of 185 inches and scientists estimate that it is close to 3,000 years old.

Disease:

  • White pine blister rust — introduced fungal disease that has afflicted the limber pine 
  • Arceuthobium cyanocarpum - dwarf mistletoe that infests limber pine populations and is the leading cause of disease-based limber pine mortality 

Comments

Sem Asmelash on April 22, 2024: