Callitris tuberculata

R.Br. ex R.T.Baker & H.G.Smith (1910)

Common names

Mallee pine (Hill 1998).

Taxonomic notes

Type: Australia, Western Australia, Goose Island Bay, Middle Island, Jan. 1802, R.Brown Iter. Austral. 3110 (Hill 1998). I am somewhat skeptical on this point. Baker and Smith (1910) refer to the type collection by Brown as the sole specimen they examined, and they reproduce a photo of its herbarium sheet, which would then be the type specimen. I cannot find a record of it online. No synonyms.

Three taxa of Callitris continue to cause considerable debate. One is a tree endemic to the Perth area; another is a shrub or small tree widely distributed in the south of Western Australia; and the third is a tree of the Murray River drainage and some outlying areas in New South Wales, Victoria, and eastern South Australia. The first is Callitris preissii, the second is C. tuberculata, and the third is C. gracilis. As with many Callitris taxa, morphological evidence is ambiguous; all taxa are distinct, but diagnostic characters tend to overlap, such that distribution and ecology may have to be considered to get to a confident identification. Farjon (2010), for instance, could not find any consistent morphological differences between C. preissii and C. tuberculata, so he united them. However, two molecular studies (Pye et al. 2003, Larter et al. 2017) place C. tuberculata sister to C. gracilis, with C. preissii in a relatively distant clade. Citing Farjon (2010), the current taxonomic authorities (POWO and Atlas of Living Australia) have chosen to lump C. tuberculata with the unrelated C. preissii rather than with its sister taxon, C. gracilis. My approach is to regard all three as distinct taxa, having distinctions in morphology, distribution, and ecology. It may yet prove appropriate to unite C. gracilis and C. tuberculata, but no authorities to date have done so.

Description

Shrubs or small trees to 8 m tall, single- or multi-stemmed. Leaves on ultimate branchlets 2-4 mm long, green or gray green, with rounded upper surface. Pollen cones clustered, cylindrical, to 5 mm long. Seed cones solitary or clustered on stout, apically expanded branchlets; globular, 20-25 mm diameter, persistent holding seeds for several years after maturity; cones scales 6, thick, irregularly tuberculate with tubercles up to 3 mm across, united to form a thick cone base, not spreading widely after opening, alternate scales reduced, larger scales obtuse; columella thick, 2-4 mm long. Seeds numerous, dark brown, with 2-3 wings 4 mm wide (Hill 1998).

C. preissii differs in being usually a single-stemmed tree rather than a multi-stemmed shrub, and in having seed cones a bit larger at 25-30 mm, and more uniformly tuberculate. C. gracilis differs in being usually a single-stemmed tree, seed cones a bit larger at 25-30 mm, and cone scales smooth or sparsely tuberculate.

Distribution and Ecology

Australia: Western Australia, widespread on red desert sandhills, plains, coastal dunes and headlands (Hill 1998). It is more adapted to extreme aridity than any of the other Callitris species (Larter et al. 2017).

The IUCN does not recognize this taxon as distinct from C. preissii. Yet, it has a limited range and the area of occupancy seems not to have been assessed. Its conservation status is therefore "not evaluated" under IUCN criteria.

Remarkable Specimens

No data as of 2024.12.06.

Ethnobotany

No data as of 2024.12.06.

Observations

It seems to be well reported at Cape Le Grand National Park in Western Australia. There are also quite a few reports near Busselton.

Remarks

Although Baker and Smith (1910) don't say so, the epithet presumably refers to the tuberculate seed cones. These are not substantially more tuberculate than the cones of several other Callitris species, but they seem to have only examined Brown's herbarium collection, and did not see the species in habitat.

Hybrids with C. preissii are found from the edges of the Great Victoria Desert west to the Murchison River estuary (Hill 1998).

Citations

Baker, R.T. and H.G. Smith. 1910. A Research on the Pines of Australia. Sydney: W.A. Gullick (p.99). Available: Biodiversity Heritage Library, accessed 2012.11.25.

Larter, M., S. Pfautsch, J.-C. Domec, S. Trueba, N. Nagalingum, and S. Delzon. 2017. Aridity drove the evolution of extreme embolism resistance and the radiation of conifer genus Callitris. New Phytologist 215:97-112.

Pye, M. G., P. A. Gadek, and K. J. Edwards. 2003. Divergence, diversity and species of the Australasian Callitris (Cupressaceae) and allied genera: evidence from ITS sequence data. Australian Systematic Botany 16(4):505-514. https://doi.org/10.1071/SB02019.

See also