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Cephalotaxus fortunei

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Cephalotaxus wilsoniana

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Detail of Cephalotaxus fruit [Ganesh Mani Pradhan, 2009.01.28].

 

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Cephalotaxus

Siebold et Zuccarini ex Endlicher 1842

Common Names

Plum yew (Vidakovic 1991), Chinese: san jian shan shu (Fu et al. (1999)).

Taxonomic notes

Eleven species in this treatment:

For most of the 20th Century this genus was generally treated as the sole genus in the family Cephalotaxaceae Neger (1907), and some authors also placed Amentotaxus (Taxaceae) in the family. Detailed embryological studies by Singh (1961) showed that Cephalotaxus development differs strongly from all genera in the Taxaceae save Amentotaxus, which exhibits some intermediate characters. However, a detailed molecular analysis by Hao et al. (2008), using both chloroplast and nuclear DNA markers to analyze all generally recognized species in the two groups, showed that the clade of Cephalotaxus with other Taxaceae genera is monophyletic. The analysis also showed that the clade C. harringtonia - C. koreana - C. wilsoniana is monophyletic, and that the latter two species could be treated as varieties of the former.

This treatment follows that of Tripp (1995) and of Fu et al. (1999), which provides detailed information for a number of Chinese species. Differences between the two treatments are noted as they occur. Tripp does not attempt a taxonomic study and notes that most key characters used to discriminate species are gradational, so that in many cases a knowledge of a specimen's provenance is necessary to confidently identify it to species (Tripp 1995).

Description

Evergreen dioecious, rarely monoecious trees or shrubs. Branches opposite or whorled. Buds ovate, covered with numerous persistent imbricate scales. Leaves spirally arranged on terminal branchlets, appearing 2-ranked on lateral branchlets, needle-like, usually pectinate with a conspicuous midrib on the upper surface and 2 broad bluish stomata bands below, each with 11-24 rows of stomata; a single resin canal below the midrib. Pollen cones axillary, globose, on twigs formed the preceding year, subtended by 1 ovate bract, up to 1 cm diameter, each with 4-16 microsporophylls each bearing 2-4 sacs of nonsaccate pollen. Seed cones borne from axils of terminal bud scales, 1-8 per bud, long pedunculate, cones pendant, drupe-like, elliptic, 2-3 cm long, with a leathery, fleshy outer covering, green to reddish, containing 1-2 wingless seeds ripening the second season. Cotyledons 2. Chromosomes n = 12, among the largest of all conifer chromosomes (Silba 1986, Vidakovic 1991, Fu et al. 1999).

Fu et al. (1999) provide a key to the Chinese species.

All Cephalotaxus appear to form vesicular-arbuscular mycorrhizas (Newman and Reddell 1987, cited by Brundrett 2008).

Distribution and Ecology

Korea, China, Japan, Burma, Laos, Vietnam and India (Vidakovic 1991, Tripp 1995). Its center of distribution is in China, which holds portions of the native range of seven species. All species are highly shade tolerant, typically growing as understory trees or shrubs in humid temperate to subtropical broadleaf forests, and are typically uncommon within their ranges. A few species can tolerate cold temperate climates (USDA Zone 5 or 6), but none can tolerate aridity, and most can be damaged by exposure to full sun. They seem to be highly browse-resistant due to unpalatability. There is some concern that they suffer from poor regeneration due to a slow reproductive cycle (about two growing seasons for both male and female full development), dioecious habit, slow growth, long distances between individual plants, and seed predation by birds and mammals (although such predation is probably the main agent of seed dispersal). All species are threatened or endangered in their native range, primarily due to habitat loss (Tripp 1995).

Big tree

See C. harringtonia.

Oldest

Dendrochronology

Ethnobotany

Many species are locally used for timber or firewood, and some (e.g., C. koreana) have been commercially exploited for timber. It has been used medicinally by native peoples, for instance by extraction of a seed oil in India. However, it has also been found to contain, like certain members of Taxus, anticancer alkaloids with names like cephalotaxine and harringtonine. This has led to exploitation for the purposes of extracting the anticancer compounds. Such exploitation threatens the survival of several species, but there is reason to hope that this can be avoided (as it was with Taxus) by synthesizing the compounds (Tripp 1995).

Observations

The species with the widest native ranges and greatest cold tolerance, C. fortunei, C. harringtonia, C. koreana and C. sinensis, can be readily found in botanical gardens and arboreta throughout the cold-temperate West. However, other species (C. griffithii, C. mannii) are not represented in any U.S. or U.K. gardens and must be seen in their rapidly-vanishing native habitats.

Remarks

The name is derived from the Greek kephale, meaning "head", and taxus, referring to the head-like shape of the staminate flowers in yew (Vidakovic 1991).

Philipp Franz von Siebold sent the first Cephalotaxus to Europe from Japan, in about 1829 (Tripp 1995).

The fossil record includes Jurassic specimens in Greenland, and Europe and NW North America during the Miocene and Pliocene (Tripp 1995).

Citations

Brundrett, Mark. 2008. Mycorrhizal Associations: The Web Resource. mycorrhizas.info, accessed 2009.06.09.

Neger, F.W. 1907. Die Nadelhölzer (Koniferen) und übrigen Gymnospermen Leipzig (pp. 23, 30-31). Available at Google Books, accessed 2012.11.22.

Newman, E.I. and P. Reddell. 1987. The distribution of mycorrhizas among families of vascular plants. New Phytologist 106: 745-751.

Singh, H. 1961. The life history and systematic position of Cephalotaxus drupaceae Sieb. et Zucc. Phytomorphology 11:153-197.

See also

Cheng Wan-chün, Fu Li-kuo & Chao Chi-son. 1978. Cephalotaxaceae. In: Cheng Wan-chün & Fu Li-kuo, eds., Flora Reipublicae Popularis Sinica 7: 423-436.

Last Modified 2012-11-23