Constructing a Multi-Stage Classification Scheme
Figure 2. A multistage classification system.
1a. Body speckled (2)
1b. Body not speckled (4)
2a. Body round Rotunda
2b. Body not round (3)
3a. Body with scalloped margin: Floribunda
3b. Body without scalloped margin: Digitorum
4a. Body striped Alternata
4b. Body not striped (5)
5a. Rounded patterns on body: Ovalis
5b. Body without circles: Amorpha
Note that there is one set of paired statements less than the number of different kinds of items. This is fewest number of steps possible.
A KEY TO THE COMMON EVERGREEN TREES IN THE FRONT RANGE OF THE ROCKY MOUNTAINSLove
1. Foliage leaves spirally arranged, needle-shaped, single or in bundles of 2 to 5; fruit a dry, scaly cone (2)
1. Foliage leaves scale-like, opposite, in pairs (12)
2. Leaves in bundles of 2 or more surrounded at base by a small sheath of thin scales; fruit a dry, woody cone (3)
2. Leaves single, without a sheath at base; scales of mature cones thin, leathery or papery (8)
3. Leaves 4 or 5 in a bundle (4)
3. Leaves 2 or 3 in a bundle (5)
4. Leaves 3.5-7.5 cm long, not sticky; cones large, 8-25 cm long, scales smooth, without spines; seeds not winged: Limber pine
4. Leaves 2.5-4.5 cm long, stick, stout and curved; cones 6-9 cm long, scales with spines (when young); seeds winged: Foxtail pine
5. Leaves short, 2-5 cm, generally in pairs; cones small, about equal length to that of needles, nearly spherical; seeds large, wingless, and edible: Pinon pine
5. Leaves 4-25 cm long, in bundles of 2 or 3. (6)
6. Leaves 4-7 cm (occasionally shorter), yellow-green; cones approx. same length as shorter leaves, persistent: Lodgepole pine
6. Leaves longer, 7-25 cm; cones 6-15 cm long (7)
7. Cones thick, hard; scales each with stout, hard prickle: Ponderosa pine
7. Cones yellowish-brown, shiny; scales usually with short prickle: Austrian pine
8. Leaves stiff, 4-angled, each jointed at base to small, hard, brownish, stem-like base; cones pendulous (9)
8. Leaves flat, not brown or wood at base; leaves fall entirely away, leaving scars on branches (10)
9. Leaves stiff, sharp-pointed; new twigs without hairs; cones more than 6 cm: Colorado blue spruce
9. Leaves less rigid and abruptly pointed; new twigs pubescent; cones less than 6 cm: Englemann spruce
10. Leaves narrowed toward base into short stalk that broadens slightly at the point of attachment; leaf scar elliptical; cones pendulous with 3-pointed bracts projecting: Douglas fir
10. Leaves not much narrowed at base; leaf scars large and circular; mature cone erect, dark purple or blackish, scales falling separately from axis of cone (11)
11. Leaves of lower branches 2.5-4.5 cm: Subalpine fir
11. Leaves of lower branches 4.5-7.5 cm; cones green, yellowish or purple: White fir
12. Fruit a berry-like structure, more or less juicy (13)
12. Fruit a cone about 1.2 cm, brownish-yellow; leaves scale-like, often glandular on back: Arbor vitae
13. Leaves awl-shaped, 6-15 mm; upper surfaces whitened; prostrate shrubs: Ground juniper
13. Leaves less than 6 mm; scale-like, not whitened above (14)
14. Leaves approx. 3 mm, pale to dark green, without hairs; fruit green, bluish-green to blue and also without hairs: Rocky Mountain juniper
14. Leaves less than 3 mm, dark green; fruit dark blue, without hairs at maturity (in Colorado, tree appears reddish-brown in winter: Eastern red cedar
Notes on Evergreens of the Rocky Mountains:
Limber pines grow on wind-swept, rocky ridges, 8000 to 11,000 ft elevation.
Foxtail pines are uncommon, growing in very exposed positions up to 12,000 ft. elevation.
Lodgepole pines are found in nearly pure stands at 9,000 to 10,000 ft. elevation, usually where fire has swept through.
Ponderosa pine is the common pine of the foothills and the lower south-facing slopes.
Pinon pine is a small to medium-sized, much-branched and shrub-like tree of the southern mountains and also near Ft. Collins, Colorado.
The Colorado blue spruce is the state tree and grows singly or in groves in canyon bottoms and along streams in the foothills and montane zones.
Englemann spruce form extensive forests in the higher mountains from 8500 ft. to timberline.
Douglasfir is valuable for its strong durable wood. It forms large dense stands on north-facing slopes in the foothills and lower montane zone.
White firs occur with Englemann spruce at altitudes of 10,000 to 11,000 ft.