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Home , Calocedrus, Pinaceae, Thuja plicata

COMMON OF THE PNW

The common conifers in the belong to the following genera: Abies, , Callitropsis, Juniperus, Larix, Picea, Pinus, , , , and . Most of the common of these genera are provided in the laboratory. Secure a sample of each of the specimens and, as you examine and study the leafy twigs, compare them to the labeled specimens around the room and answer the questions and fill in the blanks in the following exercise. As you identify your unknowns to species, label them with a piece of masking tape. The materials provided will include the following species, which are classified in the families , Pinaceae, and . In this exercise, diagnostic vegetative features of the leaves and stem are emphasized first, followed by an examination and comparison of cones (reproductive structures) and by a fill-in key to the common conifers.

Cupressaceae (Incense cedar; does not occur naturally north of Mt. Hood, OR) Callitropsis nootkatensis ( cedar) – formerly nootkatensis (Western ) (Western red cedar)

Pinaceae (Grand ) (Alpine or Subalpine fir) Larix occidentalis (Western ) (Sitka ) (Engelmann spruce) (Lodgepole ) Pinus monticola () (Ponderosa or Yellow pine) Pseudotsuga menziesii () (Western hemlock) (Mountain hemlock)

Taxaceae Taxus brevifolia (Pacific yew)

VEGETATIVE FEATURES

1. CUPRESSACEAE ( family) Four of the genera have scale-like (as contrasted to needle-like) leaves. These four genera are _Juniperus______, _Callitropsis___, _Thuja___, and ___Calocedrus___. Consider these four specimens only (there is one representative in each ). One usually will have round twigs (=stems) with 2 scale leaves opposite each other or 3 to 4 scale leaves in a whorl (arising from the same node or part of the stem), while the others appear to have flattened twigs with 2 scale leaves opposite or 4 scale leaves in a whorl. Which species has "round" twigs with the scale leaves in 2's or 3's? ___Juniperus occidentalis______

Considering the specimens with flattened twigs and with scale leaves in 2's or 4's, identify to species the following sketches of the leaves.

Label: __Calocedrus decurrens___ _ Thuja plicata _Callitropsis nootkatensis__

The ovulate (=) cones of these four genera are distinctive. In general, they are small, often nearly globose or slightly cylindrical, and composed of 2-12 scales (the structures that bear the ). The cones of the Cupressaceae are generally smaller than those to be found in the other conifers, especially those in the Pinaceae.

Which has a nearly globose, dry cone with the cone scales enlarged and thickest at the end? _Callitropsis nootkatensis__

Which has a usually bluish, often fleshy cone that does not open to shed the seeds? ___Juniperus occidentalis___

The other two genera have more elongate, dry cones with several scales. The one with only 4 to 6 scales is __Calocedrus decurrens___; the other with about 10 to 12 scales is _ Thuja plicata Which of these has the larger cones? __Calocedrus decurrens___ 2. PINACEAE (Pine family) The species in the Pinaceae have needle-like leaves, and usually rather large cones that are composed of numerous, spirally arranged cone scales. Some genera have the needles borne singly along all the twigs, usually in a spiral arrangement, others have the needles borne in small clusters or bundles of 2, 3, or 5 along the twigs, whereas others have the needles borne in terminal tufts at the tips of very short, lateral (spur) branches.

Select the four species that have needles in bunches of 2 to 5, or in tufts or spur shoots. Those that have the needles in 2's, 3's, or 5's are in the genus Pinus (); the other, which has brush-like tufts of needles at the end of spur shoots, is __Larix occidentalis___

This is a very distinctive , the only one in the Pacific Northwest that is (meaning that the leaves are all shed each fall). Note that the branches that we have now (winter) are leafless, but when the leaves flush in the spring, leaves or needles of this are young, soft, and obviously freshly grown.

Identify the other three species as follows:

Needles 2 per bundle____Pinus contorta___

Needles 3 per bundle____ Pinus ponderosa____

Needles 5 per bundle______Pinus monticola____

All the other needle-bearing species have the needles borne singly. Two genera are peculiar in that the leaves are shed rather quickly when the tree (or branches thereof) is cut; therefore, never try to use either of them as a Christmas tree! Both of these genera have leaves that, when shed, leave a tiny remnant of the leaf-base on the twig; a remnant that can be described as peg-like. In one, the pegs stand out at right angles to the stem and, in the other, they project forward. Separate the two genera with peg-like leaf scars (there are four such species).

A B

Of these four species, the two species with peg-like leaf bases as in “A”, have sharp, stiff, and more or less (in cross-section) leaves. What is the genus? ___Picea___ The two species in genus “A” can be differentiated on (1) the shape of the needles, and (2) the pubescence (“hairyness”) of the young twigs.

Of the two species in this genus, which one has somewhat dorsiventrally flattened leaves and no hair on the stems/twigs (glabrous)? (space is provided for you to make a sketch)

____Picea sitchensis______

The other species in this genus, has square leaves in cross-section (not dorsiventrally flattened) and the stems are covered with fine hairs. Which one is this?

____Picea engelmannii______

The two species in genus “B” have flat, blunt needles. Note that the leaves of one of these are very white beneath, but green above. Examine these leaves under the microscope and note that the whiteness is due to the presence of several rows of white dots (pores or stomata--singular, ). The other species is almost the same color on both surfaces (having stomata almost equally numerous on both surfaces). The first species also will have the needles tending to spread in a horizontal , in contrast to the other, where the needles tend to spread in all directions. Identify the two species.

Needles spreading in one plane, gray beneath, green above, very unequal in length:

____Tsuga heterophylla______

Needles spreading in all directions, about the same color on both surfaces, not markedly different in length:

____ Tsuga mertensiana______

Now you should have left only the species of Pseudotsuga and Abies, all of which have comparatively smooth twigs where the needles have been shed. Examine the leaf scars carefully. Some scars are nearly circular, or slightly elongate (with reference to the axis of the branch), whereas at least one of the species has the scars broader than long and somewhat crater-like or umbilicate (navel-like). Recognize the genera as represented in the following two sketches. (This is not a hard and sharp distinction, and does not always "work".)

Genus ______Pseudotsuga______Genus ______Abies______

"A" has pointed and almost sharp buds, in contrast to those of "B", which are more blunt. "A" tends to have less regular opposite branching than does "B".

What is species "A"? _____ Pseudotsuga menziesii______

Cheer up, if you cannot recognize it from the leaves, you surely can from the cones, as they are perhaps the most distinctive cones found among our conifers, having a 3- cornered bract extending past each seed-bearing scale.

To repeat, the species is ______Pseudotsuga menziesii______There are two species with leaf scars as shown in "B", both in the genus __Abies___. The species of this genus usually cannot be distinguished by the cones, since a peculiarity of this genus is that the cones are never shed in their entirety, but only scale by scale, leaving the axis of the cone on the tree, standing stiffly erect. These two species can be distinguished, though, by the presence of stomates on one or two surfaces, by differences in the arrangement and attachment of leaves, and by differences in positioning of ducts in the leaves. One species, namely _____Abies grandis____ has stomata on the lower side of the leaves, but not on the upper side (hence the leaves are gray beneath but green above). In addition, this species without stomata on the upper surface has the needles practically all spreading in a horizontal plane, the upper and lower surfaces of the twigs being similarly exposed. On this basis, identify the species as illustrated below.

To repeat, this species is _____Abies grandis____

The other species in the same genus (with leaf scars as shown in "B") has stomata on both leaf surfaces, and ± straight leaves with one broad central row of stomata on upper leaf surface. This species is:

_____Abies lasiocarpa____

As with the scale-leaved species, many of the needle-leaved conifers can be recognized by their cones alone. Consider the following features:

Two genera have cones with a 3-pointed bract arising from beneath each cone scale; the bracts may be about as long as the cone scales (barely visible) or considerably longer than the cone scales.

Which of these has the larger cone? ______Pseudotsuga menziesii____ and which the smaller? ______Larix occidentalis______. Two cones have sharp hooks or spines near the tip of the scales. One of these has somewhat lopsided, smaller cones; it is ______Pinus contorta . The other has a much larger, symmetrical cone; it is ______Pinus ponderosa______. The third species in this genus has the largest (or at least the longest) cones of our native conifers; it is ____Pinus monticola.

Of the three genera--Abies, Tsuga and Picea--the species of Abies do not shed their cones as a whole, and we shall make no attempt to distinguish between them in this exercise. Our species of Picea and Tsuga have smaller, somewhat woody cones that range in length from about 1 inch (2.5 cm) in Tsuga heterophylla, to 1-2 1/4 inches (3-6 cm) in Tsuga mertensiana, to 2 1/4-4 inches (6-10 cm) in Picea.

3. TAXACEAE (Yew family) The species in this family are characterized by the lack of woody cones; the seeds are borne singly and are surrounded by a fleshy, reddish, berry-like aril. The one native species in this family is a or small tree of the forest understory. The leaves are flat, pointed, and arranged in two rows (two-ranked) on the branches and abruptly tapered to a short, petiole-like, decurrent base. What is the genus and species?

_____Taxus brevifolia______

KEY TO COMMON CONIFERS

To summarize your study of the conifers, fill in the blanks in the following key with the proper generic and specific names. Start with the first couplet (1a and 1b). Read both leads before making a decision regarding which of the two to follow. After making a decision, proceed in like manner through the rest of the key. You are expected to recognize these species of conifers by the twigs as well as by the cones.

1a. Leaves deciduous each fall, borne in tufts of 20-50 on short lateral (spur) shoots; cones with 3-cornered bracts visible between the scales Larix occidentalis ()

1b. Leaves persistent from year to year, not borne in tufts on short lateral shoots; cones (with one exception) without visible 3-cornered bracts

2a. Leaves scale-like

3a. Twigs usually round; cones fleshy, globose, usually bluish, the cone scales not separating when the seeds mature Juniperus occidentalis (Western juniper)

3b. Twigs flattened; cones dry, globose or slightly cylindrical, not bluish, the cone scales separating when the seeds mature

4a. Cones globose; cone scales thickened and knob-like at the tips Callitropsis nootkatensis (Alaska cedar)

4b. Cones cylindrical or slightly so; cone scales not thickened at the ends

5a. Cones with 10-12 scales; leaves obviously in pairs along the twigs, the tips of the dorsal and ventral pair of leaves at a different level than the tips of the lateral pair of leaves Thuja plicata (Western red cedar)

5b. Cones with 4-6 scales; leaves apparently in whorls or 4, the dorsal and ventral pair of leaves about the same length as the lateral pair of leaves Calocedrus decurrens (Incense cedar)

2b. Leaves needle-like

6a. Needles in fascicles of 2, 3, or 5

7a. Needles 5 per fascicle Pinus monticola (Western white pine)

7b. Needles 2-3 per fascicle 8a. Fascicles containing 2 needles Pinus contorta (Lodgepole pine)

8b. Fascicles containing 3 needles Pinus ponderosa (Ponderosa or Yellow pine)

6b. Needles borne singly, not in fascicles

9a. Leaf scars raised, the twigs roughened by the peg-like projections

10a. Needles mostly square, sharp, and stiff

11a. Twigs glabrous, needles dorsiventrally flattened Picea sitchensis (Sitka spruce)

11b. Twigs pubescent with fine hairs, needles not dorsiventrally flattened Picea engelmannii (Engelmann spruce)

10b. Needles flat, blunt, and pliable

12a. Needles much more whitish on the lower surface than on the upper, tending to spread in one plane, very unequal in length Tsuga heterophylla (Western hemlock)

12b. Needles almost the same color on the two surfaces, tending to spread in all directions except perhaps on the lower surface of the twig, not markedly different in length Tsuga mertensiana (Mountain hemlock)

9b. Leaf scars not raised, either smooth or umbilicate (navel-like) or leaf scars hidden by the decurrent leaf bases

13a. Leaf bases decurrent; leaves mucronate at the apex; seeds borne singly, surrounded by a fleshy aril Taxus brevifolia (Pacific yew)

13b. Leaf bases not decurrent; leaves obtuse to rounded at the apex; seeds borne in woody cones

14a. Needle scars broader than long (with reference to the axis of the twigs); buds pointed; branches alternate or opposite Pseudotsuga menziesii (Douglas fir)

14b. Needle scars usually at least as long as broad; buds blunt; branches regularly opposite

15a. Needles without stomata on the upper surface, nearly all spreading in a horizontal plane, the upper surface of the twig (as well as the lower) not concealed by needles Abies grandis (Grand fir)

15b. Needles with stomata (and thus whitish) on both surfaces, leaves +/- straight with 1 broad central row of stomata on upper surface Abies lasiocarpa (Alpine or Subalpine fir)