''Cephalotaxus'', commonly called plum yew or cowtail pine, is a genus of
conifers
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extan ...
comprising 11 species, treated in either the
Cephalotaxaceae, or in the
Taxaceae when that family is considered in a broad sense.
The genus is
endemic to eastern
Asia, though
fossil evidence shows it had a wider
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
distribution in the past.
[ The species are evergreen ]shrub
A shrub (often also called a bush) is a small-to-medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees ...
s and small trees reaching (rarely to ) tall.
Taxonomy
Molecular studies place ''Cephalotaxus'' as the most basal member of the Taxaceae, having a very ancient divergence from them during the late Triassic.
Description
The leaves
A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...
are spirally arranged on the shoots, but twisted at the base to lie in two flat ranks (except on erect leading shoots); they are linear, long and broad, soft in texture, with a blunt tip; this helps distinguish them from the related genus '' Torreya'', which has spine-tipped leaves.[
The species can be either ]monoecious
Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy.
Monoecy is conne ...
or dioecious
Dioecy (; ; adj. dioecious , ) is a characteristic of a species, meaning that it has distinct individual organisms (unisexual) that produce male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproductio ...
; when monoecious, the male and female cones are often on different branches. The male (pollen
Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
) cones are long, grouped in lines along the underside of a shoot. The female ( seed) cones are single or grouped two to 15 together on short stems; minute at first, they mature in about 18 months to a drupe
In botany, a drupe (or stone fruit) is an indehiscent fruit in which an outer fleshy part (exocarp, or skin, and mesocarp, or flesh) surrounds a single shell (the ''pit'', ''stone'', or '' pyrena'') of hardened endocarp with a seed (''kernel'') ...
-like structure with the single large nut-like seed long surrounded by a fleshy covering, green to purple at full maturity. Natural dispersal is thought to be aided by squirrel
Squirrels are members of the family Sciuridae, a family that includes small or medium-size rodents. The squirrel family includes tree squirrels, ground squirrels (including chipmunks and prairie dogs, among others), and flying squirrels. Squ ...
s which bury the seeds for a winter food source; any seeds left uneaten are then able to germinate.[
]
Phytochemistry
''Cephalotaxus'' species produce cephalotaxine, an alkaloid. Parry et al 1980 provides evidence that cephalotaxine is a phenylethylisoquinoline. However, they also find this genus to be unable to incorporate cinnamic acid into cephalotaxine, and incorporation of cinnamic acid is usually a step in phenylethylisoquinoline syntheses, throwing the phenylethylisoquinoline theory in to question.
Extant species
The taxonomy of ''Cephalotaxus'' is difficult, because the species have been defined using characteristics that intergrade with each other, such as the length and shape of needles, bark, and stomatal band color. ''Cephalotaxus'' species have often been separated geographically rather than morphologically.
References
External links
Gymnosperm Database
*Photos
{{Taxonbar, from=Q933520
Conifer genera