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Tuesday, November 25, 2014

Abies grandis - Grand Fir

The Grand fir is another uncommon sight in our warmer climate but, to a conifer lover, a welcome one. Growing up to 250' in its native range, we will likely to see them 50-60' tall by about 15-20' wide. They form a beautiful conical shape. Generally quite dense when young eventually a bit more open. You can see the one on the left is much fuller than the one on the right. Looks like a redwood if you look quickly at the foliage. This planting has two trees, right next to a redwood, and I suspect there was some confusion at planting time or when they were pulled from a nursery. Supposed to be three redwoods?

Leaves are evergreen, spirally arranged, linear, needle-like, 3/4 - 2" long, narrow, bright green upper surface, lower surface with 2 distinct white bands of stomates. The leaves on reproductive branches are very different than lower down on the tree. Those tend to form a very strong "V" shape. This feature is common to most firs and makes this characteristic useless for identification. The lower leaves form a single flat plane with the leaves spreading out sideways. 

The leaves on the top appear to be different lengths, alternating long and short.

Bands of stomates in 2 rows on the lower portion of the leaf.

Stems are yellowish-green initially, persistently smooth, with round depressions where leaves were once attached.

Female cones are found only at the top of trees. Growing 2-4" long, yellowish green or purple green when young turning brown at maturity and like all fir trees, the cones disintegrate on the tree, shedding the seeds, scales and bracts leaving behind only the thin central stalk. Bracts shorter than scales so you don't see them until they hit the ground. In this image you can see the scale on the left has its attached bract on its "back" while the one to the right is not showing a bract.

Male cones are yellow and found on the lower branches.

Bark on trees initially is smooth, gray or silver with horizontal resin blisters, becoming furrowed or flaked with age.

First, determine that it's a fir and not a spruce. Once you a certain its a fir, you have to look at how leaves are arranged on the stems and avoid the reproductive one. Look for the presence or obscene of stomatal bands on the upper surfaces, they are always on the lower surface, not the upper for this species. Look up for cones and down for cone scales and bracts.

Not at all easily. I used my trusted Pacific Coast Trees by McMinn and Maino.
Foliage is found in one plane, often called 2 ranked but I like the plane concept, or in 1 dimension. To use a key on these you have to find the resin glands with are inside the leaf, either along the margins or near the main vein. These are shallow and along the margin. To see the resin glands you need a 10X hand lens. Cut the leaf in half crosswise and then carefully squeeze the leaf with your nail while looking for where some resin comes out.

281 Pebble Beach Drive

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