The pattern of highly disjunct distribution of geographic ranges of the species within such a genus spans temperate plant zones of continents in the Northern Hemisphere.

[7] The leaves are spirally arranged on the shoots, but twisted at the base to lie in two flat ranks; they are linear, 2–8 cm long and 3–4 mm broad, hard in texture, with a sharp spine tip.

[12] Therefore, it is generally difficult to support past presence or absence of such genera in geographic locales where macrofossil plant material is rare or absent, even if substantial pollen (as in Quaternary bogs) is available.

Species within this genus are all adapted to establish and grow slowly as subcanopy woody plants in forest habitats of moderate to dense shade.

T. jackii Chun T. nucifera (von Linné) Siebold & Zuccarini T. taxifolia Arnott T. californica Torrey T. grandis Fortune ex Lindley T. parvifolia Yi, Yang & Long T. fargesii Franchet