Cupressaceae and Taxodiaceae have recently been merged under the earlier name

 Cupressaceae s.I. by many authors, as the two families are similar in a number of morpho-

 logical characters. Sciadopitys S. et Z., which has often been treated as a morphologically

 isolated member of the Taxodiaceae, has recently been considered as a monotypic family,

 Sciadopityaceae. The Cupressaceae s.s. may be reorganized into two subfamilies. The Cu

pressoideae is composed of genera with the uppermost cone-scales infertile and can be divided

 into four tribes: Cnpresseae, including Cupressus, X Cupressocyparis, Charnaecyparis and

 Fokeinia;Thujopsideae, including Thuja, Thujopsis and Platycladusl Junipereae, includ-

ing Juniperus and Microbiota; and Tetraclineae, including Calocedrus and Tetraclinis.

The Callitroideae is composed of genera with the uppermost cone-scales fertile and can be divided into three tribes: Actinostrobeae, including Actinostrobus, Callitris, Fitzroya and

Neocallitropsis; Widdringtoneae, including Pilgerodendron, Diselma and Widdringtonia ;

Libocedreae, including Libocedrus, Papuacedrus and Austrocedrus. Five geographical dis-

tribution patterns are recognized in the 21 genera of Cupressaceae. (a) One genus, X Cu-

pressocyparis, is a natural hybrid derived from selections in England; (b) Two genera, Cu-

pressus and Juniperus, are distributed in Africa, Europe, Asia and North America; (c)

Three genera, Thuja, Chamaecyparis, and Calocedrus, are disjnnctly distributed in East-

em Asia and North America; (d) Five genera, Actinostrobus, Callitris, Libocedrus,

Papuacedrus and Widdringtonia, have limited distribution; and (e) The other 10 genera,

which are monotypic, are restricted to narrow areas except Plotycladus. Three centers of

genera diversity are identified in the Cupressaceae, i. e Eastern Asia with nine genera, southwestern North America with five genera, and Australia and its adjacent islands in the east　with six genera, including New Zealand,. Tasmania, New Caledonia, and New Guinea.

Other important areas are western Mediterranean with three genera and Chile and Argentina