For information about how you could sponsor this page, see How You Can Help
Article from New Trees by John Grimshaw & Ross Bayton
'Torreya taxifolia' from the website Trees and Shrubs Online (treesandshrubsonline.
There are no active references in this article.
Tree to 13(–18) m, 0.8 m dbh. Branchlets spreading to pendulous, yellowish green, yellowish brown or grey. Leaves 1.5–3.5 × 0.3 cm, linear to lanceolate, lower surface with two shallow, greyish bands of stomata; leaves emit a foetid smell when crushed. Male cones pale yellow, 0.5–0.7 cm long. Seed 2.5–3.5 cm (including aril); aril dark green, but purple-streaked, glaucous. Hils 1993. Distribution USA: Florida & Georgia (Apalachicola River valley). Habitat Cool, shady wooded slopes and ravines, between 15 and 30 m asl. USDA Hardiness Zone 6–7. Conservation status Critically Endangered (IUCN); Federally Listed as Endangered Species in the United States since 1984. Illustration Van Gelderen & van Hoey Smith 1996; NT867. Cross-reference K313.
Torreya taxifolia is effectively a relict species, marooned since the last glaciation (with its distant relative Taxus floridana) on the low sandy bluffs of the Apalachicola River valley in the Florida Panhandle. It was formerly reasonably abundant there, and formed good trees, whose wood was valued for items such as shingles and fence posts. In the mid-twentieth century the already reduced and stressed population became infected with a number of fungal pathogens, including Phytophthora cinnamomi and species of Physalospora and Macrophoma, which result in death of the shoots (but which can be cured with fungicide) (Esser 1993, Georgia Plant Conservation Alliance 2008). All the mature trees of T. taxifolia there are now long gone and the plant persists in the wild only as resprouting coppice stumps – of which there are probably fewer than 1000 individuals. Only one fertile tree is known, which has produced ‘approximately eight’ seeds since it was located, and no wild seedlings have been recruited for decades (Schwartz 2005). Not surprisingly, therefore, the species is of great conservation concern, with both official and unofficial efforts being directed at it. In particular, it has become a focus species in the debate over ‘assisted migration’ in the face of global warming (McLachlan et al. 2007, Nijhuis 2008).
All participants in the debate are clear that T. taxifolia is confined to the Apalachicola area only by climatic circumstances, not through an inability to grow elsewhere. This is abundantly proven by the fact that the most important remaining population of the Florida Torreya is now at the Biltmore Estate, Asheville, North Carolina, where it was introduced as an ornamental in 1896–1897 and again in 1939, when about a dozen trees were planted. It has thrived there, with mature trees up to 15 m, and the population includes numerous self-sown seedlings. This is currently the most important source of seed for distribution to individuals and institutions (Torreya Guardians 2008). The species also does well in the western states. For example, two broad, bushy specimens (grown from cuttings!) were shown to me (JMG) in the obscure location of Hawthorne Park, Medford, Oregon in 2004 by Frank Callahan, who recalled that they had been received from the US National Arboretum in about 1990. The species is established in many European collections, principally as small trees or seedlings, although it has reached 3 m at Chyverton, Cornwall (TROBI).
The officially favoured method of conservation is through traditional ex situ methods, with populations being maintained in botanic gardens and regulated collections. Atlanta Botanical Garden and other bodies in Georgia (where it is a native plant, as a few individuals grow within 200 m of the Florida–Georgia state line) are playing an important part in establishing orchards of different clones collected from the wild (Bailo et al. 1998, Georgia Plant Conservation Alliance 2008). The alternative view is that wild or semi-wild populations should be established further north in the Appalachian Mountains, where it can grow in a more suitable climate. To this end, an informal group known as the Torreya Guardians has been created, which actively promotes the planting of populations of T. taxifolia on private land outside the species’ natural range (Torreya Guardians 2008). This has raised howls of disapproval from conservationists, who principally fear the risk of it becoming an invasive species in an area where it is not native (Schwartz 2005), but has kindled debate on how species with naturally or artificially restricted ranges, threatened by climatic change (or other phenomena), should be treated. There will be many such cases in the near future, for which integrated active management will be required.