Alaska Trip #13
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Alaska Trip Page #13
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Ketchikan and Temperate Rain Forest

The quaint city of Ketchikan, Alaska.

Western hemlock rain forest near Ketchikan, Alaska.

Western hemlock forest with understory of salmonberry (Rubus spectabilis).

Lichen-covered (Usnea sp.) western hemlock (Tsuga heterophylla).

Black bears (Ursus americanus)

Black bears are common in this western hemlock temperate rain forest near Ketchikan, particularly when the steams and rivers are teeming with salmon. The forest understory also contains other bear forage plants, including salmonberry (Rubus spectabilis) and yellow skunk cabbage (Lysichiton americanum). The latter plant belongs to the pantropical arum family (Araceae), including many cultivated ornamentals such as Anthurium, Caladium, Philodendron, Dieffenbachia, and the common garden calla (Zantedeschia aethiopica). Recent studies using chloroplast DNA indicate that the arum family also contains the duckweeds, previously placed in the family Lemnaceae. Duckweeds include Wolffia, the world's smallest flowering plant, a passion of this author and the derivation of his Internet name of "mrwolffia."

Regarding black bears in this area, skunk cabbage is especially noteworthy because it provides them with a natural laxative. During months of winter hibernation, bears become very constipated. In fact, black bears can go 100 days without eating, drinking, urinating, defecating, or exercising. When they emerge from their dens in the spring, they seek out and consume skunk cabbage. This diet restores their normal (regular) bowel movement cycle.

Yellow skunk cabbage (Lysichiton americanum), a showy arum native to the Pacific northwest. Unlike some of its fetid-smelling relatives, the flower emits a slightly skunky odor. This remarkable plant is also an important laxative for black bears emerging from hibernation.
See Wayne's Word Page On Stinking Flowers
  Wayne's Word Page On The Duckweed Family  

Dead salmon along nearby stream.

Totem pole under construction by local native American. It is made from the highly prized and durable wood of western red cedar (Thuja plicata). Other Pacific Northwest cedars include Alaska or yellow cedar (Chamaecyparis nootkatensis), Port Orford cedar (C. lawsoniana), and incense cedar (Calocedrus decurrens).

Left Image: Western red cedar (Thuja plicata) photographed in Glacier National Park with author's father Paul Armstrong, August 1965.

Just when I think I have a handle on the taxonomy of cypresses and cedars (Cupressaceae), new research emerges from the amazing field of DNA phylogeny and cladistic analysis. Evidence from DNA sequencing has further complicated the taxonomy of cedars, including the transfer of Alaska cedar and Port Orford cedar into the cypress genus Cupressus. These two genera are obviously closely related to cypress (Cupressus). In addition to their similar seed cones, they are also genetically compatible. The popular Leyland cypress (Cupressocyparis leylandii) used in landscaping is a bigeneric hybrid between the Monterey cypress (Cupressus macrocarpa) and the Alaska cedar (Chamecyparis nootkatensis).

Early in this century, a new cypress species was discovered in Vietnam. It was named Xanthocyparis vietamensis. [The name Cupressus vietnamensis also appears in some garden references.] Surprisingly enough, its closest relative was found to be the Alaska cedar (Chamaecyparis nootkatensis syn. Cupressus nootkatensis), separated by thousands of miles and on opposite sides of the Pacific Ocean. The two species were so similar that the authors (A. Farjon et al 2002, working in Kew, England, combined them generically, and the Alaska cedar became Xanthocyparis nootkatensis. Port Orford cedar (Chamaecyparis lawsoniana) resembles other North American and Asian species of Chamaecyparis in both morphology and DNA, so its scientific name remains unchanged.

More Complicated Reading About Cedar and Cypress Taxonomy

The Alaska cedar is the only Chamaecyparis species that forms spontaneous, fertile hybrids with Cupressus species when these are grown together in botanical gardens. Evidence from DNA and morphology indicates that it and the Vietnam cypress are closely related phylogenetically to the New World species of Cupressus (Little et al, 2004). The Old World species of Cupressus, however, are a separate evolutionay line, as is the large genus Juniperus. In a comprehensive study, Little, D.P. (2006) proved that the Alaska Cedar and its Vietnam relative should be placed in the same genus as the New World Cupressus, but that the correct generic name for this group is Callitropsis. His study incorporated 88 morphological and wood-chemistry characteristics in 56 species of Cupressaceae, combined with sequence analysis of three chloroplast genes and two nuclear genes. The name Cupressus technically only applies to the Old World species in this genus. It turns out that Callitropsis nootkatensis was used for the Alaska cedar in 1864, long predating the name Xanthocyparis. In accordance with the Botanical Rule of Priority, the older name must be used. Therefore, Alaska cedar becomes Callitropsis nootkatensis, Vietnam cypress becomes Callitropsis vietnamensis, and the Alaska cedar-Monterey cypress hybrid becomes Callitropsis x leylandii. Damon Little (2006) also proposed that all of the New World Cupressus be placed in the genus Callitropsis. The latter genus superficially resembles the Australian genus Callitris.

Based on their general morphological appearance, the New World Cupressus certainly resemble Old World Cupressus species; however, this similarity may be due to parallel evolution (homoplasy) in similar warm, dry climates. Just because these two groups of cypress appear similar doesn't necessarily mean that they are all closely related members of the same genus. DNA comparisons appear to reflect their true genetic affinities and differences. Groupings of species, such as Callitropsis, Chamaecyparis, Juniperus and Old World Cupressus represent separate branches (clades) in computer-generated phylogenetic trees.

Using DNA To Compare Genera and Species
Homoplasy: Parallel and Convergent Evolution
Conifers Of The Palomar College Arboretum 1
Conifers Of The Palomar College Arboretum 2
  Conifers In the Taxodium Family (Taxodiaceae)  


  1. Farjon, A. et al. 2002. "A New Genus and Species in the Cupressaceae (Coniferales) from Northern Vietnam, Xanthocyparis vietnamensis." Novon 12: 179-189.

  2. Little, D.P. et al. 2004. "The Circumscription and Phylogenetic Relationships of Callitropsis and the Newly Described Genus Xanthocyparis (Cupressaceae)." American Journal of Botany 91: 1872-1881.

  3. Little, D.P. 2006. "Evolution and Circumscription of the True Cypresses (Cupressaceae: Cupressus)." Systematic Botany 31: 461-480.

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