''Taxus cuspidata'', the Japanese yew or spreading yew, is a member of the genus ''

Taxus ''Taxus'' is a genus of coniferous trees or shrubs known as yews in the family Taxaceae. They are relatively slow-growing and can be very long-lived, and reach heights of , with trunk girth averaging . They have reddish bark, lanceolate, flat ...

'', native to

Japan Japan ( ja, 日本, or , and formally , ''Nihonkoku'') is an island country in East Asia. It is situated in the northwest Pacific Ocean, and is bordered on the west by the Sea of Japan, while extending from the Sea of Okhotsk in the n ...

Korea Korea ( ko, 한국, or , ) is a peninsular region in East Asia. Since 1945, it has been divided at or near the 38th parallel, with North Korea (Democratic People's Republic of Korea) comprising its northern half and South Korea (Republic ...

, northeast

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...

and the extreme southeast of

Russia Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...

. It is an

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, whic ...

tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...

or large

shrub A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from tree ...

growing to 10–18 m tall, with a trunk up to 60 cm diameter. The

leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...

are lanceolate, flat, dark green, 1–3 cm long and 2–3 mm broad, arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flattish rows either side of the stem except on erect leading shoots where the spiral arrangement is more obvious. The seed cones are highly modified, each cone containing a single

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...

4–8 mm long partly surrounded by a modified scale which develops into a soft, bright red

berry A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, rasp ...

-like structure called an

aril An aril (pronounced ), also called an arillus, is a specialized outgrowth from a seed that partly or completely covers the seed. An arillode or false aril is sometimes distinguished: whereas an aril grows from the attachment point of the see ...

, 8–12 mm long and wide and open at the end. The arils are mature 6–9 months after pollination. Individual trees from

Sikhote-Alin The Sikhote-Alin (russian: Сихотэ́-Али́нь, , , ) is a mountain range in Primorsky and Khabarovsk Krais, Russia, extending about to the northeast of the Russian Pacific seaport of Vladivostok. The highest summits are Tordoki Yani a ...

are known to have been 1,000 years old.

Uses

It is widely grown in eastern

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an are ...

and eastern

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...

as an

ornamental plant Ornamental plants or garden plants are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars that ...

. Image:Japanese Yew Taxus cuspidata Leaf Closeup 3008px.jpg, Closeup of the leaves on a stem Image:Japanese Yew Taxus cuspidata Bark 3008px.jpg, Rough bark of the tree

Toxicity

The entire yew bush, except the

(the red flesh of the berry covering the seed), is toxic due to a group of chemicals called taxine alkaloids. Their cardiotoxicity is well known and act via calcium and sodium channel antagonism, causing an increase in cytoplasmic calcium currents of the myocardial cells. The seeds contains the highest concentrations of these alkaloids. If any leaves or seeds of the plant are ingested, urgent medical advice is recommended as well as observation for at least 6 hours after the point of ingestion. The most cardiotoxic taxine is Taxine B followed by Taxine A; Taxine B also happens to be the most common alkaloid in the Taxus species. Yew poisonings are relatively common in both domestic and wild animals who consume the plant accidentally. The taxine alkaloids are absorbed quickly from the intestine and in high enough quantities can cause death due to general cardiac failure, cardiac arrest or respiratory failure. Taxines are also absorbed efficiently via the skin and Taxus species should thus be handled with care and preferably with gloves. Taxus Baccata leaves contain approximately 5 mg of taxines per 1g of leaves. The estimated (i.e. not by any means a fact) lethal dose (LD_min) of Taxus baccata leaves is 3.0-6.5 mg/kg body weight for humans There is currently no known antidotes for yew poisoning, but drugs such as

atropine Atropine is a tropane alkaloid and anticholinergic medication used to treat certain types of nerve agent and pesticide poisonings as well as some types of slow heart rate, and to decrease saliva production during surgery. It is typically given ...

have been used to treat the symptoms. Taxine remains in the plant all year, with maximal concentrations appearing during the winter. Dried yew plant material retains its toxicity for several months and even increases its toxicity as the water is removed, fallen leaves are also toxic. Although poisoning usually occurs when leaves of yew trees are eaten, in at least one case a victim inhaled sawdust from a yew tree. The following book made it clear that it is very difficult to measure taxine alkaloids and that this is a major reason as to why different studies show different results. Minimum lethal dose, oral LD_min for many different animals were tested: Chicken 82.5 mg/kg Cow 10.0 mg/kg Dog 11.5 mg/kg Goat 60.0 mg/kg Horse 1.0–2.0 mg/kg Pig 3.5 mg/kg Sheep 12.5 mg/kg Several studies have found taxine values under 20 mg/kg in mice and rats. For symptoms of human toxicity see Taxine alkaloids Male and monoecious yews in this genus release toxic pollen, which can cause the mild symptoms see Taxine alkaloids. The pollen are also a trigger for asthma. These pollen grains are only 15 microns in size, and can easily pass through most window screens.

External links

References

{{Authority control cuspidata Trees of China Trees of Korea Trees of Japan Trees of Siberia Plants used in bonsai