Coniferales

 

Sciadopityaceae

 

The genus Sciadopitys is the only member of this Family of conifers – it is another so-called ‘living fossil’ and its nearest relatives are found in the fossil record going back 230 million years.

 

The only living representative of the genus is the Japanese Umbrella Pine – Sciadopitys verticillata. It is a very slow growing evergreen, compact, but nevertheless upright, conical tree which can reach 25m tall in favoured localities. It is usually ‘foliaged’ down to the ground with pairs of dark green structures in whorls - which are not leaves but cladodes and which resemble the spokes of an umbrella.

 

The flowers are produced at the ends of the branchlets in spring – both sexes on the same tree. The cones are oblong to ovoid and about 6-10cm long and 3-5cm broad; they ripen in the second season after pollination. There are normally between 5 and 9 seeds on each of the fertile scales. They are compressed and narrowly winged to 1+cm long.

 

The seeds are extracted by collecting the cones before they open on the tree in the autumn and then gently dried until the scales open and the seeds can be shaken free. The seeds can be stored under cool, water conserving conditions when viability will be retained at reasonable levels for a year.

 

The seed coat is hard and impermeable – sufficiently hard to require degradation before imbibition will occur and the germination process can proceed; however this is further delayed by an endogenous physiological dormancy which requires a chilling treatment before a uniform and synchronised emergence will be achieved.

 

The hard seed coat condition can be reduced by warm (20+˚C) stratification for 63 days – it would also be possible to degrade the seed coat using a soak in 1% citric acid solution for 48 to 72 hours.

 

The chilling requirement can be satisfied by treating the seeds at below 5˚C for 42 days. Germination can then be achieved at 16 to 20˚C. If the chilling requirement is not provided some of the seeds will eventually germinate – a 50% crop emerging after 75 days at 20˚C.

 

The seedlings are extremely slow growing in the initial years and it may take five or six years before a handleable seedling for growing on is attained. It is possible that this slowness may represent an unknown environmental factor – such as the absence of a relevant mycorrhizal association.