Sciadopitys Siebold & Zucc.

A genus of a single species endemic to Japan, Sciadopitys is the sole genus in the family Sciadopityaceae, an ancient coniferous lineage with no close living relatives (Farjon 2008). It is rendered distinct from all other living conifers by its foliage, the leaves being of two distinct types: reduced, scale-like, and brown on long shoots, widely spaced between nodes over most of the shoot but clustered in tight pseudowhorls near the shoot ends, these clustered scale leaves subtend the photosynthetic foliage leaves; the foliage leaves are needle-like, flattened and ‘doubled’, each being composed of two fused needles borne from the axils of the scale leaves in false whorls clustered near the ends of the shoots like the spokes of an umbrella, from which the scientific and English names are derived (Farjon 2017; Debreczy & Rácz 2011). These foliage leaves continue to divide botanists between those who consider them true leaves, and others who consider them modified shoots (cladodes).

Sciadopitys differs further from other conifers in the production of a viscous, latex-like, non-resinous sap, which has antimicrobial properties (Yates et al. 2019). The sap forms in laticifer ducts and is secreted from wounds. When exposed to air, the sap quickly hardens and the resultant seal of the wound is reputed to protect against pathogens (Yates, Earp & Walker 2006).

Traditionally, Sciadopitys was included in the family Taxodiaceae (e.g. Elwes & Henry 1906–1913) so long as this remained separate from Cupressaceae s.s., but in recent years phylogenetic studies have amply demonstrated that Taxodiaceae is nested within Cupressaceae, with Sciadopitys sister to a clade containing Cupressaceae s.l. and Taxaceae, thus Sciadopitys is now generally recognised as belonging to its own family, Sciadopityaceae (Yang et al. 2022).

Now reduced to a relict distribution in Japan, its prehistoric range is widely considered to have covered much of Eurasia. Bean observed that species of Sciadopitys ‘were so common in Germany in the mid-Tertiary that the leaf-remains give a characteristic appearance to some layers of brown coal’ (Bean 1981). More recently, Sciadopitys has been shown to be an important constituent of Baltic amber deposits, demonstrated by the recent discovery of the first pre-Oligocene macrofossil record of Sciadopitys from Europe (Sadowski et al. 2016).

Propagation by seed is quite straightforward: collections of ripe seed gathered in 2013 and sown in a coir-perlite mix placed in a cold frame germinated freely the following August in Edinburgh (TC pers. obs.). Seed of cultivated trees will likely give more mixed results (Elwes & Henry 1906–1913) although this may be better when several are grown together, as at Mount Stuart, Argyll, UK (G. Alcorn pers. comm. to TC, 2012). Seedlings and young plants benefit from additional shade during their first few summers, and occasional feeding with fertiliser formulated for acid-loving plants when grown in peat-free mixes (TC pers. obs.). Hardwood cuttings, taken in late winter, treated with hormone and placed over gentle bottom heat under plastic sheeting have given c. 50% success rates at Edinburgh (TC pers. obs.).