Botany Photo of the Day

Today's photographs and entry are courtesy of Douglas Justice, the garden's Curator of Collections. – Daniel

Taiwania, or coffin-tree, is currently recognized by most authorities as consisting of a single species, which ranges from SW China to Myanmar (Burma) and Taiwan. According to the entry on Wikipedia for Taiwania, it is the tallest species in Asia, at 80m.

UBC Botanical Garden has three wild collections of Taiwania cryptomerioides, all derived from sites in Taiwan: Tahsuehshan, 2200m (accession pictured), Tachien, 2200m, and Hsiuluan, ~ 2000 m (foliage detail accession pictured). Little seed is available outside of Taiwan, as the species is rare and now protected in China. Despite the relatively low elevation and southerly provenance of this species in Taiwan, our plants appear to be reasonably hardy in the David C. Lam Asian Garden (USDA Zone 8), having never suffered frost damage in more than 20 years. Our taiwanias are located in a variety of environments, in forest under the shade of mature Alnus rubra, Acer macrophyllum, Abies grandis, Thuja plicata and Tsuga heterophylla, and in the open. Some plants receive irrigation (our thin soils and dry summers necessitate supplemental irrigation for many ornamentals), but most have to fend for themselves. A few of the plants in the open display yellowing foliage, but all plants are growing strongly and many are strikingly beautiful, displaying the typical drooping branch tips, blue-green curtain-like foliage and narrow conical habit.

None of our plants has started coning (as outlined in our interpretive sign), although there was a report in 2006 of what could have been male cones in the upper branches of one of our oldest trees. To our knowledge, no cultivated Taiwania in a North American or European botanical garden has ever produced a seed cone. There is a point to wanting our taiwanias to produce seed cones, beyond having bragging rights. Upon reaching reproductive maturity, the leaves change from awl-shaped (similar to Cryptomeria japonica) to smaller, more appressed and scale-like (see illustration of a branch with cones via conifers.org). This is example of foliar dimorphism due to heterochrony. More significant (from a botanical point of view) is that Taiwania appears to have “features crucial to the understanding of the evolution of the cupressaceous cone, characteristic of the families Cupressaceae and Taxodiaceae, and provide further evidence for the need to merge these families”. See Farjon and Garcia's Cone and ovule development in Cunninghamia and Taiwania (Cupressaceae sensu lato) and its significance for conifer evolution and Schulz and Stützel's Evolution of taxodiaceous Cupressaceae (Coniferopsida).