Trees of Victoria


licorice fers

Conifer Identification


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Taxonomy

Conifers are Gymnosperms of the Family Pinaceae, and the Division Pinophyta. They are defined as having "naked seeds", referring to the fact that conifer seeds are not contained within fruit tissue. The seeds are instead borne on scales, which are grouped together to form cones. Most conifers have persistent foliage (evergreen) consisting of needles or scales.

Table 1. Conifer families, some of which can be found on the Pacific coast of Canada, as either native specimens or as exotic plantings.
Taxonomic family Common name Species Local Species
Pinaceae Pine family 342 pines, spruces, firs ...
Cupressaceae Cypress family 186 Leyland Cypress, ...
Podocarpaceae Podocarpus family 182 no local species
Araucariaceae Araucaria family 39 Monkey-puzzle tree
Taxaceae Yew family 28 yews
Cephalotaxaceae Plum yew family 11 no local species
Phyllocladaceae Celery Pines 5 no local species
Sciadopityaceae Umbrella Pine family 1 Umbrella Pine

Conifer Key 1: What kind of Conifer?

In this discussion I will be focussing on trees native to Vancouver Island and those exotic species that have been planted on Vancouver Island. Additional details and characteristic features will be provided in later sections covering the individual genera and species. Refer to dichotomous Key 1.

a dichotomous key to conifer genera
Conifers Key 1. Identification key to conifer genera.


A. The first step in identification is to determine the Genus of the species examined. To do this, examine the leaves first. Are the leaves needle-like (fig. 1) or scale-like (fig.2).

needle-like conifer leaves
Figure 1. Needle-like conifer leaves.
Scale-like conifer leaves
Figure 2. Scale-like conifer leaves.


Conifers with needle-like leaves

B. Next we examine how the needle attaches to the branchlet. Are single needles attached directly to the branchlet (fig.1) or are they attached in clusters (fig.3)?

Conifer needles that are attached in clusters.
Figure 3. Conifer needles attached in clusters.


Needle attachment

C. The next character to examine is how the needles are attached to the branchlet. Is there a wooden peg-like structure (sterigmata) that attaches the needle to the branchlet (fig.4, fig.5) or does the needle tissue attach directly to the branchlet (fig. 6)?
Conifers that have needles that are directly attached to the branchlet with a suction-cup-like base are in the Genus Abies, firs.

illustration of a spruce brnchlet showing sterigmata.
Figure 4. Spruce branchlet showing sterigmata.
Firs are mostly defined by two features 1) upright cones instead of hanging cones and 2) needles attached directly to the branchlet. Other characteristic features of firs will be discussed in the section on Abies.

Conifers that have needles that are not attached directly to the branchlet, may be spruce, hemlock, yew, or Douglas-fir. Among these genera however, the spruces (Picea) have the most easily observed defining characteristic, the sterigmata. These structures can also be seen when the needles have fallen off the branches leaving the peg-like sterigmata that roughen the surface.

spruce branchlet showing needles attached by sterigmata.
Figure 5. Spruce needles attach to the branchlet on sterigmata.
a fir branchlet showing needles attached directly to brnchlet.
Figure 6. Fir needles attached directly to branchlet.

With or without petiole

D. To determine difference between spruce and the others, we must look at the structure of the leaf. The petiole (stem) is the structure that attaches the leaf to the branchlet. In true firs (Genus Abies) the leaf is attached directly to the branchlet, in spruces there is a woody sterigmata that attaches the leaf to the branchlet, in the other Genera there is a petiole or a petiole-like structure that is intermediate between the leaf and the branchlet. The difference between spruce and hemlock, yew, and Douglas-fir, can be seen in the following figures.

Closeup of hemlock needles
Figure 7. Needle attachment in hemlocks.
Closeup of yew needles showing needles attached to a decurrent petiole.
Figure 8. Needle attachment in yews.
Closeup of Douglas-fir needles showing the leaf scar and the petiole.
Figure 9. Needle attachment in Douglas-fir.

Hemlock needles taper abruptly to a petiole that attaches to a small spur on the branchlet. The yew needles have a decurrent petiole that continues down the side of the branchlet after it joins (fig. 8). Douglas-firs are distinguished from the others by the raised leaf scar and short petiole joining the needle to the branchlet (fig. 9).

Conifers with clustered needles

E. Conifers with a clusters of 2-5 needles (fig. 10) that are bound together with a fascicle (fig. 11) are in the Genus Pinus.

A cluster of pine needles
Figure 10. A cluster of pine needles.
a fascicle of pine needles.
Figure 11. A fascicle is a papery wrap that binds pine needles into a bundle.

Conifers with a clusters of more than 6 needles (fig. 3) could be either true cedars, genus Cedrus, or larch, genus Larix. Those of genus Larix have soft deciduous needles and small cones that can either hang or be upright, while Cedrus species have stiffer evergreen needles and rotund upright cones.





Identification of Abies Species: Introduction

This section will cover the identification of true firs, Abies genus. The identification of exotic firs presents some challenges. On Vancouver Island there are only three species of true firs, Abies Grandis (Grand fir), Abies amabilis (Amabilis fir) and Abies lasiocarpa (Subalpine fir). If we include exotic firs planted on Southern Vancouver Island, there are more than seventeen species of true firs. Creating an identification guide for exotic species is challenging because we have very few examples of each species, (sometimes incorrectly identified) and the published literature is often inconsistent.

In order to create consistent identifications, each tree was located, measured, and characteristics were recorded and photographed. In this way, as we encounter more species, we contribute to a database of characteristics that should eventually build consensus. This identification guide only includes species that I have encountered in the greater Victoria area. The following table lists the characteristics sampled in order to create this guide.


Table 2.Characteristics sampled and photographed for species identification.
 
1. needle length (n=30) 9. mature female cone colour
2. needle tip shape 10. cone bract exsertion
3. needle groove and midrib occurrence 11. male cone colour
4. number of stomatal lines on lower needle surface 12. new branchlet colour
5. occurrence of stomata on upper needle surface 13. new branchlet surface texture
6. foliage arrangement on branchlet 14. occurrence of hairs on branchlet
7. winter bud morphology 15. position of resin canals in needle
8. young female cone colour 16. bark colour and form

Abies: Identification

I have attempted to use characteristics that are easily visible for this guide, however I am compelled to avoid easily visible ones like needle tip shape, when those are inconsistent on a given species. Unfortunately to separate some species, I will need to refer to traits that are less easily seen, such as position of the resin canals in a needle cross-section. In some instances the colour and morphology of the female cones are needed to determine identity, so observations of trees may need to be done when these structures are mature, and since in most firs the cones are at the top of the trees, binoculars or a telephoto lens may be required. Refer to the dichotomous Key 2 for this discussion.




Abies Key 2. Identification key to Abies species.

Location of stomata

A. One of the most useful characteristics to examine when identifying firs is whether there are stomata on the upper side of the needles. Stomata are the microscopic structures in plant leaves that allow gas exchange by opening and closing as required. In many species, like firs, the stomata have a white waxy bloom that surrounds the opening and assists in waterproofing. All firs have stomata on the underside of the needles (fig. 12) and are easily visible as bands of white lines. Some firs have stomata on the upper side of the needle as well (fig. 13). Examine the fir needles through a magnifier to determine whether there are stomata on the upper side of the needles.

The bottom of a fir needle showing lines of stomata
Figure 12. The bottom of a fir needle showing several lines of stomata.
Top of fir needle showing stomata at the tip
Figure 13. The top of a fir needle showing lines of stomata at the tip.


Colour of mature female cones

B. True fir cones do not fall to the ground when ripe; they disintegrate releasing their seeds while still on the branch, leaving only a central spike. In addition, most fir cones are high up in the top of the tree, making examination of them more difficult. After fertilization, the young female cones swell and develop into mature cones and then turn brown and disintegrate. The mature cone colour is a good diagnostic feature. Some mature cones are purple (fig. 14) and some are green (fig. 15).

A purple cone of Abies homolepsis
Figure 14. A purple cone of Abies homolepsis, Nikko fir with hidden bracts.
 a mature green fir cone
Figure 15. A mature green fir cone with hidden bracts.


Cone scale bracts exsertion

C. The developing female cone contains the seeds layered between the cone scales. The cone scales have bracts that may be exserted (showing) between the scales (fig. 16) or hidden (fig. 15) depending on the species. These are best evaluated on the mature cone.

A fir cone with exserted cone scale bracts.
Figure 16. A fir cone with exserted cone scale bracts.

Needle arrangement

D. The arrangement of the needles around the branchlets can be helpful in determining identification. A branchlet that has needles arrange in mostly one plane is called "pectinate" (comb-like). If the needles are distributed evenly around the twig (360°) it is referred to as "bristle brush" (Table 3). Other species may have the needles that appear to be distributed over the 270° of the branchlet cross-section. Some species have shorter needles on the upper side of the branchlet and these may be parted to form either a narrow or wide V.

Table 3. Summary of foliage arrangement in firs.
Degrees Name Symbol Image Species
180° pectinate illustration of 180 degree foliage arrangement pectinate foliage arrangement Abies grandis
270° 270 270 degree foliage arrangement 270 degree foliage arrangement with v Abies nordmanniana
270° V 270 degree foliage arrangement with v 270 degree foliage arrangement with v Abies numidica
360° bristle brush illustratioon of a 360 degreee foliage arrangement A branchlet showing 360 degree arrangement of foliage Abies pinsapo


Abies: Identification continued

To continue from Abies-Key2, we look at species that have stomata on both the upper and lower surfaces of the needles (A-Abies Key 3). Some species have either blue/purple cones and others have green mature cones (B). Among the species with blue/purple cones, there are those which also have exserted cone scale bracts (C). There are only two species that conform to these characteristics (in our study area), the Fraser Fir (Abies fraseri) and the Noble Fir (Abies procera). These can be separated by needle length, but The Noble fir also has a unique feature we can look for. The needles bend parallel to the branchlet before they join forming a shape that looks like a hockey stick (Fig. 17).


Abies Key 3. Identification key to Abies species continued.

Closeup of Noble fir needles showing hockey stick shape of needles at attachment.
Figure 17. Needle attachment in Nobel fir.


Resin canal location

D. The position of the resin canals in the needles of firs is a useful characteristic for identification. In some species there can be variation in their position between needles on fertile and nonfertile branches. Our sampling was confined to the lower easily accessible non-fertile branches. Resin canals can be either median or marginal in position (Fig. 17, Fig. 18)

A cross-section of a fir needle showing the position of median resin canals
Figure 17. A cross-section of a fir needle showing the position of median resin canals.
A cross-section of a fir needle showing the position of marginal resin canals
Figure 18. A cross-section of a fir needle showing the position of marginal resin canals.





E. Returning to Abies species with green mature female cones (B), we look at species that have needles that are longer than 25mm. Abies concolor is an easily recognizable species. Its foliage has a very gray-green appearance due to the abundance of white stomatal lines on the upper and lower sides of the needles and its foliage has a sparse and mostly pectinate (comb-like) arrangement on the branchlets.

F. Among the species with needle lengths less than 25mm, Abies cephlonica has female cones with exserted bracts (Fig. 16) and marginal resin canals (Fig. 18).

The two species with needle lengths of less than 25mm, cones with hidden bracts, and median resin canals are the Algerian fir (Abies numidica) and the Spanish fir (Abies pinsapo). These two species can appear alike, but the Spanish fir has very short needles (8-20mm) and a 360° (bristle brush) needle arrangement on the branchlets (Table3), while the Algerian fir has a needle length of 15-25mm and a 270° needle distribution. (Table 3)