Gymnosperms (Seed Producing Plants: Conifers, Cycads, Ginkgo) • Earth.com

Yew

(Taxus)

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Description

“Pet poisonous” – Toxic parts: bark, leaves, seeds Taxus is a genus of small coniferous trees or shrubs in the yew family Taxaceae. They are relatively slow-growing and can be very long-lived, and reach heights of 2.5-20 metres (8.2-65.6 ft), with trunk girth averaging 5 metres (16 ft). They have reddish bark, lanceolate, flat, dark-green leaves 10-40 millimetres (1-2-1 1-2 in) long and 2-3 mm (3-32-1-8 inch) broad, arranged spirally on the stem, but with the leaf bases twisted to align the leaves in two flat rows either side of the stem. The seed cones are highly modified, each cone containing a single seed 4–7 mm (5⁄32–9⁄32 inch) long partly surrounded by a modified scale which develops into a soft, bright red berry-like structure called an aril, 8–15 mm (5⁄16–19⁄32 inch) long and wide and open at the end. The arils are mature 6–9 months after pollination, and with the seed contained are eaten by thrushes, waxwings and other birds, which disperse the hard seeds undamaged in their droppings; maturation of the arils is spread over 2–3 months, increasing the chances of successful seed dispersal. The male cones are globose, 3–6 mm (1⁄8–1⁄4 inch) across, and shed their pollen in early spring. Yews are mostly dioecious, but occasional individuals can be variably monoecious, or change sex with time. All of the yews are very closely related to each other, and some botanists treat them all as subspecies or varieties of just one widespread species; under this treatment, the species name used is Taxus baccata, the first yew described scientifically. Other sources, however, recognize 9 species, for example the Plant List. The most distinct is the Sumatran yew (T. sumatrana, native to Sumatra and Celebes north to southernmost China), distinguished by its sparse, sickle-shaped yellow-green leaves. The Mexican yew (T. globosa, native to eastern Mexico south to Honduras) is also relatively distinct with foliage intermediate between Sumatran yew and the other species.

Taxonomic tree:

Domain:
Kingdom: Plantae
Phylum: Coniferophyta
Class: Pinopsida
Order:Taxales
Family:Taxaceae
Genus:Taxus
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