Knobcone Pine

Knobcone pines (Pinus attenuata) are rather short-lived with a life-span averaging about 60 years. A small tree, this native species varies in form and size depending whether it grows in an exposed or sheltered area. In extremely poor sites it can be shrubby. Shade intolerant, knobcone pines can be found in widely scattered localities below 6,200 feet in the coast ranges between Western Oregon and Baja California. Their habitat is shallow, rocky, infertile soils, especially serpentine soils.

The slender trunk is generally forked in older trees creating a sparse crown with an irregular, open, branching pattern. Mature knobcone pine bark is a dull greyish-brown and may be tinged with purple. Shallow furrows are separated by large, loose, scaly ridges.

Knobcone pine needles (leaves) are a pale green and occur in bundles of three with a persistent sheath. The needles often have a slight twist. They remain on the tree about four or five years.

The pollen cones are conical, orange-brown and occur in tight clusters. Seed cones are asymmetrical, elongated and recurved. Buff in color, knobcone pine seed cones are set in whorls of 3 to 5 (or more) along the trunk and main branches. Persistent, the seed cones may remain on the tree for 15 to 25 years or more. The cones stay on the tree so long they are often embedded within the growing wood of the trunk – “the tree that swallows itself”. The scales have prickles and are massive on the upper side, particularly near the base where they look “knobby”. The scales are thick and flat elsewhere on the cone. Knobcone pines mature at an early age with small trees barely eight feet tall bearing seed cones.

Knobcone pine seed cones are serotinous, that is, they require fire to crack the resin seal and allow the scales to open. (Occasionally the cones will open during successive days of extreme heat in the summer.) The blackish seeds have wings, a high rate of germination and remain viable no matter how old they are, readily sprouting after a forest fire. Because of this fire requirement for seed release, knobcone pines are considered “fire forest trees”. (I should do a post on fire forest trees soon.)

Knobcone pine wood is light, soft, coarse-grained and brittle with no commercial value except as firewood.

Another common name for P attenuata is narrowcone pine. Pinus tuberculata is a synonym.

These knobcone pines were photographed along the Babyfoot Lake Trail in Rogue River -Siskiyou National Forest, Josephine County OR. The site, as seen in the pictures, is recovering from the massive Biscuit Fire in 2002.

 

 

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3 Responses to Knobcone Pine

  1. tonytomeo says:

    Knobcone pine is native nearby, and was supposedly seeded or plugged into areas that were burned by a few forest fires in the 1950s. Nowadays, no one knows if they were seeded into areas that were already occupied by knobcone pines, or if they were just put there while the native species recovered . . . or if they were seeded or plugged at all. Those that are in grid patterns were likely plugged, but not for reforestation so much as for quick firewood. It seems odd that such a pine would be used for reforestation back than, and that the seed or seedlings were even available. At a time when not many were concerned with ecology, trees that were more important commodities would have been more of a priority.

  2. Another informative post which led me to enquire further especially on ‘serpentine’ soils, a term which I’ve not come across before. Fascinating endemism and adaptive speciation and that coupled with a fire ecology. Here in my ‘neck of the woods’ fire ecosystems need burning every 10 – 15 years, too frequently or overly long periods also create havoc.
    I like the description of ‘the tree that swallows itself’ – burying it’s cones by growth.
    I’ll watch out for your fire tree posts. With the affects of climate change, fire intensity is such a concern – though its disruptive factor is all part of an ecosystem.

    • gingkochris says:

      Serpentine soils and their endemic species are prevalent within a few hour’s drive of our ranch. I love to go explore those areas and always find some fascinating plants. We recently returned from a week at Great Basin National Park and I am anxious to do a couple posts on some of the species I discovered there. But fire-type trees remain on my “to do” list.

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