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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The ten remaining genera of ancient conifers representing the Cheirolepidiaceae, Ullmanniaceae, and Voltziaceae (Mapes & Rothwell, 1991; Miller, 1977) were analyzed first with group 1, consisting of the Majonicaceae, Taxodiaceae, Sciadopityaceae, and Cupressaceae, using Ernestiodendron as the outgroup, and then with group 2, consisting of the Majonicaceae plus Pinus, Araucaria, Podocarpus, and Cephalotaxus, using both Ernestiodendron and Moyliostrobus as the outgroup.
The strict consensus tree ((Aethophyllum, Pseudovoltzia, Dolmitia) Pinus, Podocarpus, Cephalotaxus, Majonica) outgroup) shows Aethophyllum on an unresolved trichotomy with Pseudovoltzia and Dolmitia.
Alternative positions have to do with how Dolmitia, Psuedovoltzia, Araucaria, and Cephalotaxus assort on their subclade.
One of the equally parsimonious trees has the Cephalotaxus subclade of the strict consensus sharing a node with Pararaucaria; one is like the strict consensus; and in the third Cephalotaxus, Pararaucaria, and the Araucaria subclade of the strict consensus branch from an unresolved trichotomy.
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].
Torreya is distinguished from Cephalotaxus by its sessile or subsessile axils, lack of a prominent mid-rib, sunken stomatal bands that are narrower than or equal to the midrib and spine-tipped leaves.