Cephalotaxus harringtonia

Cowtail Pine
Close-up of a specimen in the Botanical Garden in Berlin
Conservation status
Least Concern (IUCN 2.3)[1]
Scientific classification
Kingdom:	Plantae
Division:	Pinophyta
Class:	Pinopsida
Order:	Pinales
Family:	Cephalotaxaceae
Genus:	Cephalotaxus
Species:	C. harringtonia
Binomial name
Cephalotaxus harringtonia K. Koch

Cephalotaxus harringtonia, commonly known as Cowtail Pine or Japanese Plum Yew, is a coniferous bush or small tree in the plum yew family. It is native to Japan, but is occasionally utilised in western gardens and several cultivars exist for these purposes. Japanese plum yew has been in cultivation in Europe since 1829, many modern horticulturists are familiar with the Japanese species Cephalotaxus harringtonia, named in honor of the Earl of Harrington, one of the first to grow the plant in a European garden.

Description

New shoots of C. harringtonia remain green for three years after forming and have ribs at the leaf bases. The buds are green in colour, globular in shape and very small at only 1 mm in length. There is one rank of leaves present on either side of the shoot, and these rise up above it and curve slightly inwards, forming a narrow V-shape somewhat akin to a dove's wings. The ranks are often vertical, but can be more flattened in shaded parts. The leaves are broadly linear in shape and measure about 5 cm long by 0.3 cm wide. They are abruptly pointed at the apex, leathery in texture and a bright matte yellowish-green on the upper-surface. The abaxial surface, or underside of the leaves, shows two broad, pale to silvery stomatal bands.^[2]

Coloured plate from the book Flora Japonica, by Philipp Franz von Siebold and Joseph Gerhard Zuccarini

The species is diecious and the male plants are typically densely covered with pairs of flowers that are pale cream in colour, though they become brown with time, and globular in shape. They are borne on 2 to 4 mm stalks beneath each pair of leaves. Pollen is released from March until May. The female individuals have two pairs of knob-like globose flowers that appear on curved stalks at the bases of the shoots. The fruit is obovoid in shape and measures 2.5 cm long by 1.5 cm wide. They are a smooth and pale green ín colour with dark green stipes, though when ripe they turn brown.^[2] An Australian company, ChemGenex Pharmaceuticals Ltd., is developing a leukemia therapy called Omacetaxine derived from the leaves of this yew species.ChemGenex Poised for Rebound

Taxonomy

The Japanese plum yew was first considered to be a yew when it was partially described by Thomas Andrew Knight in 1839 and as such was named Taxus harringtonii. It was then moved into the current genus by Philipp Franz von Siebold and Joseph Gerhard Zuccarini in 1846, though with a new specific name, making the new name Cephalotaxus drupacea. Some botanists consider C. koreana and C. sinensis to be synonymous with C. harringtonia.^[3]

Range and habitat

C. harringtonia is present in Japan. Within Japan, the tree ranges from Kyūshū in the south to Hokkaidō in the north. More specifically, it is found in Hondo in the Chiba Prefecture on Mount Kiyosumi, which is located in the Awa District within the Awa Province. It is also found in the Nagasaki Prefecture and the Hiroshima Prefecture. The variety nana is found in eastern Honshū as well as Hokkaidō, most notably on seaside cliffs and in mountainous areas.^[4] They thrive in partial shade on deep, rich soils.^[3]

Cultivation

Cephalotaxus harringtonia 'Fastigiata'

C. harringtonia has been in cultivation in the United Kingdom since 1829 and is infrequnetly encountered as a garden specimen. Of the several species that exist in the genus, the Japanese plum yew is the one most often encountered in western gardens.^[3] Several cultivars exist:

• 'Fastigiata' was first selected in 1861 in Japan. It grows to 6 metres in height and it characterised by its broad cluster of erect stems and very dark green leaves that spread all around the stem and are strongly decurved. The shoots are unbranched in the upper parts of the plant, while the lower parts have somewhat chaotic projecting side-shoots that hang down and contain leaves in flat ranks. The flowers are also inconspicuous.^[2]

• 

  Plant with a chaotic projecting side-shoot

See also

• Omacetaxine mepesuccinate, an alkaloid from this plant and a potential anti-cancer drug

References

1. ^ Conifer Specialist Group 2000 (2006). Cephalotaxus harringtonia. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 June 2007.
2. ^ ^{a b c} Mitchell, Alan (1974). Trees of Britain & Northern Europe. London: Harper Collins Publishers. pp. 54. ISBN 0-00-219213-6. 
3. ^ ^{a b c} Earle, Christopher J. (2006). "Cephalotaxus harringtonia". The Gymnosperm Database. Archived from the original on 2007-04-05. http://web.archive.org/web/20070405131227/http://www.conifers.org/ce/ce/harringtonia.htm. Retrieved 2007-06-11. 
4. ^ Tripp, Kim E. (1995). "Cephalotaxus: the plum yews". Arnoldia (Harvard University Press) 55 (1): 24–39.