Geography 316:  Biogeography    
The Biogeography of  the California Nutmeg (Torreya Californica).
 
by Anica Williams, student in Geography 316  Fall 2003
 
Thank you for visiting our site. This web pages was written by a student in Geography 316: Biogeography and edited by the instructor, Barbara Holzman, PhD.  All photos and maps are posted with specific copyright permission for the express use of education on these web pages. The students have tried to be as accurate as possible with the information provided and sources and references are cited at the end of each page.
 

Taxonomy: (USDA, 2003)
 

Kingdom         Plantae
Subkingdom   Tracheobionta
Subdivision    Spermatophyta
Division Coniferophyta
Class Pinopsida  
Order Taxales
Family  Taxaceae
Genus Torreya Arnott
Species Torreya californica Torr. -  California nutmeg


Species Name: Torreya californica (named after John Torrey, 1796-1875, noted American botanist, Maxwell, 1992)

Common Names: (USDAFS, 2003)

California torreya
California nutmeg
stinking yew
stinking nutmeg
stinking cedar       
 

 

Figure 1. Torreya californica in Mendocino County, California. Photo by Anica Williams (2003).

 

  Description of Taxonomy:

            The following description of the classification of the Torreya Californica was taken from the same source (unless otherwise noted), Hyperdictionary, 2003. The kingdom Plantae is comprised of all living or extinct plants and the subkingdom Tracheobionta includes all vascular plants. The subdivision Spermatophyta is comprised of seed plants, i.e. plants that reproduce by seeds. Coniferophyta is the division that includes conifers (cone-bearing), gymnosperms, dating from the Carboniferous period. The class Pinopsida includes most conifers and the order Taxales is coextensive with the family Taxaceae. The family Taxaceae includes the Yew family. The genus Torreya Arnott “is characterized by furrowed bark and whorled or opposite and drooping branches and linear, evergreen, fetid foliage, with pale bands of stomata on the lower surface, the upper dark green, with the margins curved under” (Peattie, 1991, p. 290). The species Torreya californica is a small to moderate sized tree native and endemic (limited) to California (Calflora, 2003).

 

Introduction:

Growing up in the redwood forests of Mendocino County I thought that I knew all the native plants, especially the trees in the area but little did I know I was missing the elusive and endemic California nutmeg (Torreya californica). In September 2003, I was introduced to this extraordinary tree on a San Francisco State University Biogeography field trip to Samuel P. Taylor State Park in Marin County. It looked like a young redwood tree and I realized that I’d probably seen a California nutmeg before but had mistaken it for a redwood. After feeling the sharp point of its leaf tips in my hand I would never make that mistake again. I vowed that I would pay this amazing organism its due respect by passing on its intriguing story. So, I hope you enjoy reading this as much as I enjoyed writing it. 

 
Figure 2. Torreya californica, California.
Photo by Brother Alfred Brousseau © 1995 Saint Mary's College of California (CalPhotos, 2003).

Description of Species:
(Source: Whitney, 1992; unless otherwise noted)

            The Torreya californica is a strongly aromatic tree with a conical or rounded crown and rows of slender, spreading branches (Figure 1). It ranges in height from 16 to 70 feet (5 - 21m), with a diameter of 8 inches to 2 feet (0.2 - 0.6m), sometimes larger.
            The needles of the T. californica are evergreen, alternate and spreading in 2 rows (Figure 2). They are 1 to 2 ¾ inches (2.5 – 7 cm) long and are less than 1/8 inches (3 mm) wide with long sharp points at the tips. The needles are mostly paired, flattish, slightly curved, stiff and almost stalkless at base. The needles are shiny dark green above and green with two narrow whitish lines beneath.
            The bark is gray-brown and thin with irregular fissures into narrow scaly ridges. The wood is light, soft and yellow (Munz and Keck, 1959). It has a fragrance similar to sandalwood and when freshly cut it can make ones skin itch (Murray, 1985). The twigs are mostly paired and slender. They are  yellow-green and turn reddish brown.
            T. californica is one of the few native conifers that are dioecious, meaning the male and female flowers are on separate trees (VTFD, 2003). The seeds are 1 to 1 ½ inches (2.5 – 4 cm) long. They are an obovoid-ellipsoid shape with a fleshy green outer layer (Figure 3). When the seed is ripe the outer layer becomes streaked with purplish markings and sheds. The seeds inner layer is yellow-brown, thick-walled, resinous, endosperm copious and stalkless. The seeds mature in two seasons and are scattered and single on leafy twigs. The seed resembles the aromatic and deeply folded seed coat, to those of the unrelated commercial spice, nutmeg (Myristica fragrans), hence the name California nutmeg. Male or pollen cones are 3/8 inches (10 mm) long. They are elliptical, pale yellow and single at leaf bases.

 
Habitat:

         The T. californica grow in mixed evergreen forest habitats, with Douglas fir, yellow pine, redwood, western hemlock, grand fir, tanoak and California laurel (Whitney, 1992). They are usually found growing along mountain streams and especially in cool deeply shady slopes and canyon bottoms. They are also found on exposed slopes with chaparral and on shaded slopes in the belt between redwood pockets and chaparral (Howell, 1949).  The T. californica is rare and widely scattered with a relatively low density of individual species in a given area (Maxwell, 1992). Seed dispersal is limited to a short distance from the parent tree because the seeds are too large and heavy for wide dispersal (Murray, 1985). Trees of both sexes have to grow near one another in order to produce viable seeds.

 

Reproduction:
          T. californica mainly reproduces sexually, with some asexual reproduction in the form of root sprouting, occurring after damage to the above ground portion of the tree. Torreyas are wind pollinated and male trees must normally be within 75 to 90 feet (23-27 m) of female trees in order to effect pollination (UADAFS, 2003). Male flowers are small, elliptical, pale yellow, and occur at the base of the leaves; female flowers are tiny, consisting of an ovule surrounded by a fleshy sac and are borne on current year twigs (VTFD, 2003). Flowers are produced from March through May and seeds ripen from August until October and are released from September through November (UADAFS, 2003). Seed production is usually erratic and a good crop may be followed by crop failure the next year (UADAFS, 2003). Seeds average 12 to 15 months dormancy, i.e. from the time the fruit ripens and falls from the tree to when the seed cracks through the seed coat (Maxwell, 1992). Because the seeds are large and heavy wind dissemination is rare and seeds usually fall near parent tree. Seed predation by Stellar’s and scrub jay is high (UADAFS, 2003).

 

Figure 3. Seed of the Torreya californica, Yosemite National Park, California (1955). Photo by Charles Webber © 1998 California Academy of Sciences (CalPhotos, 2003).

Anthropogenic Uses:

Native American Use: Pomo Indians, of Mendocino County, used the root strands for basket making and the sharp needles for tattooing (Maxwell, 1992). They would use the rigid, sharp-pointed leaves as needles to prick pitch soot into their skin for tattooing (Burke, 1975). The kernels or seeds were roasted to overcome the bitter, tannin taste and prized as a food source for Native American (Maxwell, 1992). Bows were also made from the trees strong wood (Whitney, 1992).

Forestry Uses/Value: Because of its scattered occurrences the Torreya californica has never been commercially logged (Murray, 1985). Although, it was thought that it could be grown commercially for prized wood the tree has never become commercial (Murray, 1985). Even though it has never been an important timber species, it has been logged in the past on a limited bases especially when growing with redwoods (UADAFS, 2003). The wood does have special qualities, such as its attractive yellowish color, strength, smooth grains, rot resistance and durability, which make it suitable for carving and furniture. The wood was historically used for making cabinets, wooden turnware, and novelty items, as well as for fuel and fenceposts (UADAFS, 2003).

Other Uses: It is sometimes planted in landscape gardening as an ornamental plant but the pungent odor of the leaves makes it less attractive. The seed oil has the 
potential to be used in cooking, as it is similar in quality to olive and pine nut oil (UADAFS, 2003). Apparently, seeds of the related Asian species, Torreya 
nucifera, are harvested and made into a high-quality cooking oil.
 
Largest Tree:

           The largest registered T. californica is on the American Forests’ National Register of Big Trees list and is found in Swanton, Santa Cruz County, California, Figure 4 (American Forests, 2003). In 1992, the last time it was measured, its height was 96 feet, its circumference was 251 inches and its spread was 68 feet, it is probably bigger now (American Forests, 2003). Up until 1983 there was an even bigger T. californica registered with the AFA National Register of Big Trees growing near Fort Bragg in Mendocino County, California (Murray, 1985). It stood 141 feet high and had a girth of 14 feet 10 inches before it was cut down by timber thieves, in 1983 (Murray, 1985).

Evolution:

The genus Torreya is an old taxon, with shoot and leaf fossil material found in Yorkshire, England and in Bornholm, Denmark from the Middle Jurassic Period (170 million years ago) (Maxwell, 1992). Earlier fossils, from the Cretaceous Period (144 to 65 million .years ago), have been found in North Carolina and Colorado (Maxwell, 1992). In the Tertiary Period (65 to 2 million years ago) the genus was found in the western United States and Continental Europe (Maxwell. 1992). By the Pliocene epoch (5.1 to 2 million years ago) it had spread into central and southern Europe and central Japan. During this pre-Pleistocene period the genus Torreya was a widespread circumpolar flora with a circumboreal distribution, found in the high latitudes (Howell, 1949).

Figure 4. The largest recorded Torreya californica, Swanton, Santa Cruz County, California. Photo by The Davey Tree Expert Company (American Forests, 2003).

       “Both Florin (1963) and Barbour and Major (1988) attribute the eventual shrinkage of range [of the g. Torreya] to “deterioration” of the climate leading up to the Pleistocene glaciations, [1.8 million to 11,000 years ago]” (Maxwell, 1992, p.16). With this theory the genus Torreya would be a climatic relict, since its distribution may have been affected by this past changes in climate. The Ice Age of the Pleistocene caused the flora to migrate further south from its previous locations in the north to southern Europe, Asia and North America. Eventually the genus disappeared in Europe and was limited to its present distribution in Asia and North America.  

        There is further speculation as to the reasons for the sparse and disjunct distribution of Torreya. According to Stebbins and Major (1965) Torreya is classed as a paleoendemic, meaning that its status as an endemic is the result of shrinkage of a previously widespread distribution (Maxwell, 1992). According to Fiedler and Ahouse (1991) the causes of its rarity are “1) earth history, evolutionary history and taxon age; 2) population dynamics, taxon ecology and reproductive biology; and 3) coevolution, stochasticity and taxon genetics” (Maxwell, 1992, p. 25). These factors help to explain the elusive distribution of the Torreya genus.
           Plate tectonics may have also played a role in the distribution and habitat characteristics of the genus Torreya.The habitat characteristics of the Torreya were very different when it evolved, 170 million years ago (Maxwell, 1992). What is thought to be a g. Torreya specimen was collected from the Jurassic-age Upper Gondwana formation in southeastern India, which was then in the Southern Hemisphere (Maxwell, 1992). Taxaceous (Yew) wood specimens were also collected from the Jurassic period in India. The significance of this discovery is overwhelming, as “these specimens represent the only known occurrences of distinctly Gondwanan taxads” (Maxwell, 1992, p. 17). Fossil records show that the g. Torreya was also in the Northern Hemisphere land mass of Laurasia, which included North America and Eurasia. If the g. Torreya evolved in these two distinct land masses, then elements of the habitat of the modern genus may represent an environmental continuum with these distant habitats (Maxwell, 1992). An environmental continuum explains the survival a species. Since the environmental continuum of the g. Torreya is obscure, focus shifts to how the genus has survived by looking at its ability to reproduce despite immense environmental variations (Maxwell, 1992).  There are still many questions as to how the g. Torreya has survived and reproduced for millions of years despite the fact that it has such large seeds.
       
When looking at the evolution of the g. Torreya we must consider the coevolution of the taxa. Coevolution is a form of evolution in which living things affect each other’s adaptations (Burnie, 1994). According to Maxwell (1992), there are no signs that other extant tree genera have coevolved with g. Torreya in the Jurassic Period.  Even coevolution with fauna, such as birds and small mammals, that could disperse seeds was rare or absent. It seems that this genus has had to depend of force of gravity as its seed dispersal mechanism from the beginning.
        
No clues have been found as to the ancestors of the family, Taxaceae (Yew family), in which the Torreya californica belongs (Beck, 1988). Even though the family Taxaceae has been associated with conifers they may have evolved from a different ancestral source.  According to Beck (1988), Florin believed that the Taxaceae did not evolve from the Walchiaceae, like other conifers have. There are some structures, such as the secondary shoots, of the Taxaceae that differ greatly from conifers, further obscuring their relationship. However, on closer analysis Pant (2000) suggests that members of the Taxaceae family are closer to conifers than was previously thought.

 

Distribution:

Figure 5: Distribution of Torreya Californica. 
 

The distribution of the species Torreya californica is limited to California, i.e. it is endemic to California. The species is restricted to two distinct areas, the Coast Ranges (mountains of central and northern California) and the western slope of the Sierra Nevada foothills, with no connecting link between the two ranges (Figure 5). On the coast they are found at elevations up to 3600 ft, from Mendocino to Santa Cruz counties (Peattie, 1991). In the Sierra Nevada foothills it is found at elevations up to 6000 feet, from Tulare to Tehama counties (Peattie, 1991). Precipitation is a limiting factor for the distribution of the T. californica because they aren’t found in the arid regions of southern California (Barbour and Major, 1977). They inhabit areas with a mean annual rainfall of 46.4 inches (Maxwell, 1992).

Torreya is an old taxon and its seeds are by far the largest to have survived and reproduced for at least 170 million years (Maxwell, 1992). The genus Torreya was once widespread throughout the Northern Hemisphere with fossil records showing it in Europe, Greenland, Alaska, British Columbia, Oregon, Colorado, Virginia and North Carolina (Stein, 2000). This genus now has an extremely spatially disjunction distribution. The reason for its present discontinuous pattern may be due to the inability of the genus to compete with newer life forms, making it an evolutionary relict. One cause for the genus’ inability to compete may be due to its limited dispersal because of its large seed size.
        In total there are five species and one variety under the genus Torreya (Burke, 1975). The genus Torreya is now only found in parts of eastern Asia and two small and distinct enclaves in North America, California (T. californica) and a small range in northern Florida (T. taxifolia) (Burke, 1975).   T. taxifolia is an endangered species and the current hypothesis for its decline is a result of fungal infestation attacking trees under conditions of increased environmental stress (Schwartz and Hermann, 2003). T. nucifera is found in central Honshu, Japan and possibly Korea (Burke, 1975). The species T. grandis is found in eastern China and T. jackii is found only in Zhejiang province, China (Maxwell, 1992).  The one variation, T. grandis var. fargesii Silba, occurs in northeast China and Burma (Maxwell, 1992). 
        The distribution of the yew family, Taxaceae, is also mostly limited to the Northern Hemisphere. It’s found in Europe (Britain to N Iran), Asia (USSR, Korea, Japan, China, Taiwan India, Burma, Vietnam, Philippines), North America ( Arkansas to California, eastern Canada, eastern USA, Florida, Mexico, Guatemala, El Salvador) and South America (Earle, 2002). The current distribution pattern of Taxaceae may be the result of a relicted distribution from the Luarasia landmass.

 

Bibliography

  American Forests. 2003. National Register of Big Trees, Torreya Californica page. [Online]. Available: http://www.americanforests.org/resources/bigtrees/register.php?details=2515

Barbour, M. and J. Major. 1977. Terrestrial Vegetation of California. New York: John Wiley and Sons.

Beck, C. 1988. Origin and Evolution of Gymnosperms. New York: Columbia Press.

Burke, J. 1975. Human Use of the California Nutmeg Tree, Torreya California, and of Other Members of the Genus. Economic Botany. 29 p. 127-139.

Burnie, D. 1994. Concise Encyclopedia of Nature. New York: Dorling Kindersley.

Calflora. 2003. Taxon Report: Torreya californica Torrey (Taxaceae). [Online]. Available: http://www.calflora.org

CalPhotos, University of Berkeley Digital Library Project. 2003. Torreya californica photo collection. [Online]. Available: http://elib.cs.berkeley.edu/cgi/img_query?where-genre=Plant&where-taxon=Torreya+californica

Earle, C. 2002. Gymnosperm Database, Taxaceae Page. [Online]. Available: http://www.botanik.uni-bonn.de/conifers/ta/index.htm

Howell, J. 1949. Marin Flora. Berkeley: UC Press.

Hyperdictionary. 2003. [Online]. Available: http://www.hyperdictionary.com

Maxwell, Andrew. 1992. Mapping and habitat analysis of the California endemic tree, Torreya californica, in Marin County. San Francisco, CA.

 Munz, P. and Keck, D. 1959. A California Flora. Berkeley: UC of Cal Press.

 Murray, Marshall. June 1982. Hunting the California Nutmeg. American Forests. 91 40-41.

Pant, D. August 2000. Inclusion of Taxaceae in a Separate Order, Taxales. Current Science. 79 (3) 278-279. [Online]. PDF Available: http://tejas.serc.iisc.ernet.in/~currsci/aug102000/op181.pdf

Peattie, D. 1991. A Natural History of Western Trees. Boston: Houghton Mifflin Co.

Schwartz, M. and Hermann, S. 2003. Environmental Change and the Florida Torreya. [Online]. Available: http://biology.usgs.gov/s+t/noframe/j218.htm

Stein, W. 2000. Torreya Arn., torreya. Woody Plant Seed Manual. [Online]. PDF Available: http://wpsm.net/Torreya.pdf

U.S. Department of Agriculture (USDA), Natural Resources Conservation Service. 2003. Plant Profile: Torreya californica Torr. [Online]. Available:
http://plants.usda.gov/cgi_bin/topics.cgi?earl=plant_profile.cgi&symbol=TOCA

 U.S. Department of Agriculture Forest Service (USDAFS), 2003. Index of Species Information, Species: Torreya californica. [Online]. Available: http://www.fs.fed.us/database/feis/plants/tree/torcal/all.html

 Virginia Tech Forestry Department (VTFD). 2003. California nutmeg Taxaceae Torreya californica. [Online]. Available: http://www.cnr.vt.edu/dendro/dendrology/syllabus/tcalifornica.htm

 Whitney, Stephen. 1992. The Audubon Society Nature Guides: Western Forests. New York: Alfred A. Knopf.

 
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