Viaje A La Semilla

PBIO Presentation
Pacific Yew

Introduction:
* When learning about Gymnosperms in class I found this particular conifer interesting as it was an exception to the rule and did not producecones.
* Taxonomy:
* Kingdom:Plantae
* Division: Pinophyta
* Class:Pinopsida
* Order:Pinales
* Family:Taxaceae
*Genus:Taxus
* Species: T. brevifolia
* Order and Significance:
* Distinguishing characteristic is cone, produced by all Pinales
* The Pacific Yew is a rarespecies of the family, listed as threatened or endangered.
* Physical Characteristics:
* Shrub/small tree
* Up to 20 m tall
* Yellowish-green
* Leaves are needle-like* Cones clustered into spherical shape, seed surrounded by red outgrowth called aril; fleshy cup—an outgrouwth from the base of the ovule
* Seed: dark, hard, single, erect, broad at base* Related Species:
* Taxus baccata- European Yew- medium growing evergreen tree, seed cones highly modified containing one seed, leaves as highly poisonous
* Taxus canadenis- CanadianYew, conifer, thrives in swampy woods, found as rare ice age relict, usually a sprawling shrub
* Taxus chinensis- Chinese Yew, large ornamental evergreen shrub
* Taxus sumatrana- verytall, thrives in subtropical forests and highlands, its oil is used to mark a red spot on the forehead of a Brahmin.
Evolution:
* Gymnosperms- 280 million years ago
* Position in phylogenetictree in pine tree
* Significant Evolutionary Innovation for Yews:
* Leaves: spirally arranged along twigs, have darker green color on top and lighter on bottom, this helps absorb as much lightcoming from above as possible. The leaves in shady regions are wider than those in sunny areas.
* Branches: very long in order to provide for wider leaves, which helps once again with the...