Cephalotaxus


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Cephalotaxus

 

(plum-yew), a genus of coniferous evergreen trees or shrubs of the family Cephalotaxaceae. The plants have densely foliated opposite or verticillate branches. The leaves are narrowly linear and distributed in two rows on the lateral shoots. The microstrobiles consist of seven to 12 microsporophylls, made up of spherical clusters in the leaf axils of the previous year’s shoots. The megastrobiles consist of two ovules located in the axils of the thickened opposite scales. A cone contains three or four megastrobiles; one or two large seeds with a fleshy outer coat and a fine woody interior develop in each megastrobile.

There are six or seven species of plum-yew, distributed in the eastern Himalayas, China, Korea, and Japan. Some species are cultivated as ornamentals for parks and gardens. In the USSR two species are found in the Caucasus and on the southern shore of the Crimea. C. drupacea, a shrub or tree reaching a height of 12–15 m in its native habitat (Japan and Central China), has gray bark with desquamate longitudinal bands. In cultivation it has various decorative forms (dwarf, columnar). C. fortunei, a species from China, has reddish bark and long pendulous branches.

REFERENCES

Derev’ia i kustarniki SSSR, vol. 1. Moscow-Leningrad, 1949.
Takhtadzhian, A. L. Vysshie rasteniia, vol. 1. Moscow-Leningrad, 1956.

V. N. GLADKOVA

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One of the four equally parsimonious trees has Schizolepis branching from a polytomy, as in the strict consensus tree; in another the genus branches from a trichotomy with Cephalotaxus and a subclade made up of Araucaria, Dolmitia, and Pseudovoltzia; and in a third tree Schizolepis occurs at the base of a subclade consisting of the latter three taxa and Cephalotaxus.
This group shares a node with Araucaria, which in turn is linked with Cephalotaxus.
A third tree shows Voltzia diverging from an unresolved polytomy that also bears Podocarpus, Majonica, and a subclade made up of Dolmitia, Pseudovoltzia, Araucaria, and Cephalotaxus.
Ullmannia branches from the basal polytomy of the Majonicaceae, along with Majonica, Podocarpus, and a clade with Dolmitia, Pseudovoltzia, Cephalotaxus, and Araucaria.
1993) found the genus to have a sister-group relationship with Cephalotaxus and both grouped with Taxodiaceae, Cupressaceae, Sciadopityaceae, and Araucariaceae.
Casting some doubt on a hypothesis of close relationship of Sciadopitys with Cupressus and Taxodium is the shifting of the former genus to unresolved positions when it is analyzed with Araucaria, Cephalotaxus, Pinus, or Podocarpus [ILLUSTRATION FOR FIGURES 9-12 OMITTED].
When analyzed with basal conifers, Cephalotaxus branches from a basal trichotomy that also bears Majonica and the Dolmitia-Pseudovoltzia subclade [ILLUSTRATION FOR FIGURE 7D OMITTED].
Florin (1951) and Schweitzer (1963) thought that the Cephalotaxaceae evolved from ancestors more like Ernestiodendron than Utrechtia (formerly Lebachia), because the ovuliferous scale in Cephalotaxus seems to consist of fertile elements only.
1994) based on DNA sequences in the rbcL gene shows the closest agreement with the present analyses, in that Cephalotaxus appears basal to genera of the Cupressaceae and Taxodiaceae and distal to the Podocarpaceae and Pinaceae.
It diverges from a basal polytomy of the Majonicaceae when analyzed with basal conifers [ILLUSTRATION FOR FIGURE 7E OMITTED] and branches from a position basal to the three genera of the Majonicaceae, Araucaria, Cephalotaxus, and Podocarpus in the analysis of group 2 conifers [ILLUSTRATION FOR FIGURE 13 OMITTED].
Price and Lowenstein (1989), using immunological distance based on antisera, found Pinus on a subclade diverging basal to the sister taxa Araucariaceae and Cephalotaxus and distal to Podocarpus.
Similarly, Podocarpus is basal in the subclade including Pinus, Cephalotaxus, and the Araucariaceae in work based on immunological distance by Price and Lowenstein (1989), and analyses based on rbcL sequences (Brunsfeld et al.