Cephalotaxus fortunei
Cephalotaxus griffithii
Cephalotaxus hainanensis
Cephalotaxus harringtonii
Cephalotaxus koreana
Cephalotaxus lanceolata
Cephalotaxus latifolia
Cephalotaxus mannii
Cephalotaxus oliveri
Cephalotaxus sinensis
Cephalotaxus wilsoniana
Cephalotaxus, commonly called plum yew or cowtail pine, is a genus of conifers comprising 11 species, treated in either the Cephalotaxaceae, or in the Taxaceae when that family is considered in a broad sense.[1][2] The genus is endemic to eastern Asia, though fossil evidence shows it had a wider Northern Hemisphere distribution in the past.[1] The species are evergreen shrubs and small trees reaching 1.0–10 metres (3–33 ft) (rarely to 20 metres (66 ft)) tall.
Molecular studies place Cephalotaxus as the most basal member of the Taxaceae, having a very ancient divergence from them during the late Triassic.[3]
The leaves 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, 4–12 centimetres (1+1⁄2–4+3⁄4 in) long and 3–4 millimetres (1⁄8–5⁄32 in) broad, soft in texture, with a blunt tip; this helps distinguish them from the related genus Torreya, which has spine-tipped leaves.[2]
The species can be either monoecious or dioecious; when monoecious, the male and female cones are often on different branches. The male (pollen) cones are 5–8 millimetres (13⁄64–5⁄16 in) 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-like structure with the single large nut-like seed 1.5–4 centimetres (5⁄8–1+5⁄8 in) long surrounded by a fleshy covering, green to purple at full maturity. Natural dispersal is thought to be aided by squirrels which bury the seeds for a winter food source; any seeds left uneaten are then able to germinate.[2]
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.[4]