Everything about Taxaceae totally explained
The family
Taxaceae, commonly called the
yew family, includes three genera and about 7 to 12 species of
coniferous
plants, or in other interpretations (see Classification, below), six genera and about 30 species.
They are much branched, small
trees and
shrubs. The leaves are
evergreen, spirally arranged, often twisted at the base to appear 2-ranked. They are linear to lanceolate, and have pale green or white stomatal bands on the undersides. The plants are
dioecious, rarely
monoecious. The male
cones are 2-5 mm long, and shed
pollen in the early spring. The female cones are highly reduced, with just one ovuliferous scale and one seed. As the seed matures, the ovuliferous scale develops into a fleshy
aril partly enclosing the seed. The mature aril is brightly coloured, soft, juicy and sweet, and is eaten by
birds which then disperse the hard seed undamaged in their droppings.
Classification
The Taxaceae is now generally included with all other conifers in the order
Pinales, as
DNA analysis has shown that the yews are monophyletic with the other families in the Pinales (Chase
et al., 1993; Price, 2003), a conclusion supported by studies (Anderson & Owens, 2003). Formerly they were often treated as distinct from other conifers by placing them in a separate order
Taxales.
The genera
Torreya and
Amentotaxus, previously included in this family, are better transferred to the
Cephalotaxaceae, as genetic tests show they're more closely related to
Cephalotaxus than to
Taxus. Alternatively, they may be included, with
Cephalotaxus, in a broader interpretation of Taxaceae as a single larger family (Price, 2003). In this sense, the Taxaceae includes six genera and about 30 species.
The differences between the Taxaceae and the Cephalotaxaceae are as follows:
| Family | Taxaceae | Cephalotaxaceae |
| Cone aril | partly encloses seed | fully encloses seed |
| Cone maturation | 6-8 months | 18-20 months |
| Mature seed length | 5-8 mm * | 12-40 mm |
* To 25 mm in
Austrotaxus
A few botanists have transferred
Austrotaxus to its own family, the
Austrotaxaceae, suggesting it may be closer to the
Podocarpaceae than to the other Taxaceae, but genetic evidence doesn't support this transfer.
Further Information
Get more info on 'Taxaceae'.
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