Pinus attenuata aka Knobcone Pine

Pinus attenuata, or knobcone pine, belongs to the pine family, Pinaceae. This evergreen tree grows in western North America. Its native range runs from southern Oregon to northern Baja California. It occurs in scattered populations across several mountain ranges. These include the Cascades, Coast Ranges, and Sierra Nevada. It grows from sea level to about 5,500 feet [1,676 metres].

In gardens, expect a tree about 30–50 feet [9–15 metres] tall. Some trees reach 70 feet [21 metres]. Growth is fast, and the young crown is narrow and pointed. Trees often form two or three trunks. Branches spread almost level, then turn upward at their tips. The crown grows less even with age. Some trees develop several twisted tops rather than one straight leader.

Young bark is thin and may flake from the trunk. Its gray-brown surface can show red or orange tones. Older bark develops grooves and scaly ridges. The stout twigs are reddish brown and often carry resin. Green to yellow-green needles grow in groups of three. They measure about 0.25–0.6 feet [0.075–0.18 metres] long. Some needles twist, and they remain for four to five years. Sources describe them as flexible or stiff.

Each tree bears both male and female cones. The male cones form tight, brownish-purple groups. Young female cones are small and reddish purple. Mature seed cones turn yellowish brown and curve to one side. They reach about 0.26–0.49 feet [0.08–0.15 metres] long. Raised knobs mark the scales on the outward-facing side. Scales facing the stem stay flatter. Cones cluster along branches, away from the tips. Groups may hold three to six cones, or many more. They can stay shut for as long as thirty years. Growing wood can surround cones left on the tree. Fire heat opens them and releases their seeds. Many seedlings can then establish a new stand.

Grow knobcone pine in full sun and well-drained soil. Oregon State recommends moist ground with gravel or sand. It lists the species as hardy to USDA Zone 7. This tree sees little use in formal landscapes. Its uneven shape and lasting cones suit naturalized settings. The cones also provide a clear link to its fire-driven life cycle.