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Thursday, March 10, 2011

Pinus radiata - Monterey Pine

Pinus radiata

Conifers are my favorite group of trees, and Pinus is my favorite genus. It's best to start with my favorite group. Also, might as well start with a very common native of the area. You can see this tree all along the freeway and in most neighborhoods in the county.

Pinus radiata, commonly known as the Monterey Pine is a very interesting pine tree. It has a very restricted native distribution, and is also considered to be one of the most widely planted conifers in the world, particularly in the southern hemisphere for timber use. 

There are said to be 3 native populations, all in the fog belt of coastal California. One in San Mateo and Santa Cruz counties near the county line at Ano Nuevo. The second in Monterey county, (you have to go see them at Point Lobos) and the third in Cambria. There is also one or two subspecies from the islands of Cedros and Guadalupe off Baja.

Monterey Pine is a popular landscape tree in England. We generally don't plant them here, ahh yes the grass is always greener. This one is in Beth Chatto's Garden.

The first time I heard about mycorrhizae years ago at the College of San Mateo, it concerned Monterey Pines in Australia, funny that I completed my PhD with mycorrhizae.

Trees can range from 45-90' tall. Usually single stemmed but occasionally multi-stemmed. The branching habit is pretty distinct, with the primary scaffold branches angled about 45 degrees. As these branches grow the tree takes on a broad diamond shape. As the trees age they eventually develop into a tall tree with a somewhat open rounded or flat topped canopy. As I mentioned they are very popular elsewhere. They grow really fast when young. Most pines only put out one whorl of branches per year and this one can put out several.

Young trees are rapid growers and form a narrow upright form.

Monterey Pine is a 3 needle pine. The needles are medium bright green, but can also be pretty dark, about 3-6" long. (The two subspecies have only 2 needles so watch out). Color seems to be related to age, younger trees being darker green. Needles are blunt tipped, not sharply pointed. Note in the image below that the sheath is about 1/4 - 1/2"and more or less gray. The sheath is the "wrapping" around the base of the leaves. The leaves are retained for 4 years before being shed. This is important in identifying a pine you don't know, you need to see how many years of leaves there are on a branch. How do you do that? We will discuss that some other time when we talk pines.

The cones are very attractive and quite symmetrical when open still attached to the tree and when on the ground. All pines have scales that are radially arranged but when these open they are very attractive. Cones are 3-6" long, light brown and ovoid shaped. They are held on the branches asymmetrically, usually in groups of 3. They have a short stalk or none at all.

They are reported to open mostly by fire but they also open in hot weather. You can tell they open without fire as most of the trees in residential areas are not the result of fire. The cones do stay attached for many years.

Early in the spring the male and female "flowers" appear. They are really a special type of reproductive structure called a strobilus, and not real flowers. Anyway, the females can be very attractive but you may not notice them as much as the males. The reason for this is that the females are usually near the top of the tree and the males are low down on the tree, plus the males release the yellow rain or the pollen and you tend to notice that more.

As I mentioned, these pines are a bit unusual and may produce 2 sets of cones in one year.

Bark is an attractive gray to reddish brown, deeply V-furrowed. This is an old tree.


Other 3 needle pines in our area:
P. attenuata, Knobcone Pine is native to the northern county and can be seen in UCSC wild areas. Cones are very different, in large clusters on the main stems and held for years.
P. canariensis, much longer softer needles, longer cones, much fuller habit but more or less the same overall shape but way full.
P. coulteri, longer bluer leaves, more stiff and dont seem to droop on the stems, not as restricted to the ends of the branches as they last 3-4 years. Much broader habit. There are some around.
P. jefferyi, the cones are different in that the prickle on the scale is curved inward and will not stick you and you will not likely see one in SC.
P. radiata, covered earlier, dark green leaves, shorter and softer.

Interesting specimens can be seen everywhere, but you should to go see them at Point Lobos, with the mixture of the blue water and the cliffs, just remarkable. Don't forget to look at the Monterey Cypress on the cliffs as well. Go to Waddell Creek by the county line, the olds ones are covered with moss, and those that are still alive are pretty nice. Pinus radiata is susceptible to pitch canker that kills many of our trees.

There is a nice specimen on E Cliff in Capitola
In the south county there is a real survivor in the rail junction yard on Salinas Rd in Pajaro.
This is the large one in Aptos Village across from the entrance to the park. (Hope they don't cut it down when "they" redo the village.)

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