**Botanical Characteristics and Distribution**:
– Taxus trees have slow-growing seeds that can reach heights of 2.5–20m.
– They have reddish bark, lanceolate dark-green leaves arranged spirally.
– Yews are commonly found in moist temperate or tropical mountain forests.
– Taxus baccata is native to Europe and western Asia, while Taxus cuspidata is found in East Asia.
– Taxus brevifolia ranges from California to Alaska.
**Taxonomy and Phylogeny**:
– Taxus is Latin for the tree traditionally used to make javelins.
– Yews are closely related, with some considered subspecies of Taxus baccata.
– Taxonomy varies from treating all yews as subspecies to splitting species based on morphological differences.
– Cladograms show the evolutionary relationships between yew species.
– Yew species are distributed across North and South Eurasia, North America, and Sumatra.
**Toxicity and Allergenic Potential**:
– All yew species contain poisonous taxine alkaloids.
– Eating yew berries without removing the seeds can be fatal.
– All parts of the tree except the arils are poisonous.
– Male and dioecious yews release cytotoxic pollen causing various allergic reactions.
– Male yews are highly allergenic, while female yews are considered allergy-fighting.
**Uses, Cultivation, and Horticulture**:
– Yew wood is traditionally used for making bows, like the famous yew longbows.
– Yews are widely used in landscaping and ornamental horticulture, with over 400 cultivars named.
– Some yew cultivars have yellow leaves known as golden yews.
– Yew trees have cultural significance and are often associated with themes of life and death.
– Yew trees are commonly found in church graveyards and symbolize sadness.
**Chemistry and Medicinal Significance**:
– Pacific yew and Canada yew were initial sources of paclitaxel, a cancer-fighting compound.
– Over-harvesting of yews for paclitaxel led to concerns of endangerment.
– Methods to produce paclitaxel semi-synthetically were developed.
– Docetaxel, a paclitaxel analogue, is derived from the European yew.
– Yew trees have medicinal and cultural significance, with references in various literary works and art.