Atherospermataceae

 

This small Family is now separated from the Monimiaceae and contains fourteen species in seven genera. They are all natives of the Southerm Hemisphere and occur in Chile (2 species and Eastern Australasia (12 species). They are chiefly subtropical and tropical in distribution but the three genera – Atherosperma, Laurelia and Laureliopsis - occur in adjacent temperate areas of the Southern Hemisphere – they are however only marginally hardy, as the young growth is susceptible to late sprig frosts which are not a normal occurrence in their native environments, and therefore will only develop satisfactorily in milder niches in the UK.

 

All the species are evergreen trees or shrubs and have aromatic wood, leaves and flowers. They all flower early in the year, are normally dioecious and produce their fruits after midsummer. The seeds are feathery achenes and they all have some degree of immaturity to the embryo at the dispersal stage.

 

Atherosperma

 

The monotypic genus - Atherosperma moschatum – is an evergreen tree or shrub - it occupies some of the hardiest provenances of the entire Family. It occurs commonly in coastal parts of South East Australia and in most of Tasmania. In this latter, southern extreme of its distribution it can reach a height of 40m. It therefore has the widest potential for cultivation in the British Isles.

 

The flowers are produced in clusters, in the axils of the leaves, during midwinter and have white petals with a yellow (sometimes maroon) centre. The fruits, which mature soon after midsummer, are roundish green capsules; these open at the top to release the numerous feathery achenes which are dispersed by wind. The viability level between samples of seeds can be notoriously variable but is however usually low. As the quality of a sample will deteriorate fairly quickly after dispersal it is advisable to process the fresh seed.

 

The seed does not exhibit any dormancy controls and germination will occur at reasonably high temperatures (18-20˚C) but allow for the period of embryo maturation before emergence occurs.

 

Laurelia

 

The second genus consists of two species - Laurelia sempervirens (from Chile) and L. novae-zelandii (from New Zealand). Both of these very similar species are inhabitants of temperate rainforest or damp woodland at low elevations. Neither of the species is fully hardy - especially when young - although the presence of many mature trees in the South West of England and similar mild niches bears witness to the greater hardiness of the adult specimen which by implication has survived some extreme conditions during its existence.

 

The plants are dioecious - but hermaphrodite flowers do occasionally occur. The flowers are small, inconspicuous and yellow.

 

The fruits are pear shaped, green capsules, the seeds are liberated from the top of the capsule which opens to allow the numerous wind dispersed achenes, which have a feathery ‘tail’, to disperse.  The small seeds show low viability and have an oily food reserve.

 

Preferably fresh seeds should be processed quickly in order to prevent losses in viability. The maturation of the imbibed embryo in the seed will occur naturally after a latish summer dispersal and this is then followed by a winter chill.

 

Thus imported seed will require a warm water soak to imbibe the seed and then warm stratification for 60 days followed by a chill for 42 days.

 

Laureliopsis

 

Laureliopsis is a monotypic genus (now separated from Laurelia) and contains only L. philippiana (Laurelia serrata) which is an evergreen tree native to the southern, temperate rainforests of Chile and Argentina. It resembles the previous genus morphologically and is similar in having aromatic wood and leaves. The plants are monoecious – the racemes overall appear to be made up of white flowers - these however have reddish centres with greenish white tips to the petals. This plant is from a southern provenance in Chile and Argentina and during the winter can be under a considerable blanket of snow – it should therefore prove hardy (more than it is currently credited with) in southern parts of the UK.

 

The fruit is a greenish, fleshy urn shaped capsule which splits to liberate the wind dispersed achenes which are dark brown spindle shaped seeds, about 1cm long, subtended by coffee coloured hairs. These have low viability – rarely exceeding 30%. It is therefore prudent to process fresh seed quickly.

 

The dispersal of the seed takes place soon after midsummer which thus allows the imbibed embryo to mature during the late summer and autumn before it is subjected to a winter chill. Thus a suitable protocol for imported seeds would be a) imbibition by a warm water soak, b) warm stratification for 60 days and then c) 60 days of chill.