Kingdom Plantae Order Cupressales / Pinales Higher classification Pinales | Division Pinophyta Scientific name Taxaceae Rank Family | |
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Lower classifications Taxus, English Yew, Torreya nucifera, Torreya grandis, Amentotaxus | ||
Taxaceae /tækˈseɪsiː/, commonly called the yew family, is a coniferous family which includes seven genera and about 30 species of plants, or in older interpretations three genera and 7 to 12 species.
Contents
They are many-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 millimetres (0.079–0.197 in) 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. However, the seeds are highly poisonous to humans, containing the poisons taxine and taxol.
Yew bonsai taxus taxaceae
Classification
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 micromorphology studies (Anderson & Owens, 2003). Formerly they were often treated as distinct from other conifers by placing them in a separate order Taxales. Ernest Henry Wilson referred to Taxaceae as taxad in his book ”1916, Conifers and taxads of Japan".
Some studies in the early 2000s suggested the genera Torreya and Amentotaxus were better transferred to Cephalotaxaceae, as genetic tests showed they are more closely related to Cephalotaxus than to Taxus. More recent studies have 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 suggested between Taxaceae and Cephalotaxaceae were based on the morphology of the seeds, with Taxaceae having smaller mature seeds growing to 5–8 millimetres (0.20–0.31 in) in 6–8 months and not being fully enclosed by the aril. Cephalotaxaceae seeds show a longer maturation period, ranging from 18–20 months, with the mature seeds fully enclosed in the aril and ranging from 12–40 millimetres (0.47–1.57 in).
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 does not support this transfer.