Callitris (cypress-pine) description

Callitris

Ventenat 1808

Common names

Australian cypress (Christiansen 2000), Cypress-pine (Wunderlin 1993).

Taxonomic notes

A generally recognized, distinctive genus within the Cupressaceae, here treated in 18 species:

Syn: Frenela Mirbel 1825; Fresnelia Steudel; Leichardtia Sheph.; Pachylepis Brong.; Octoclinis F. Mueller 1858; Parolinia Endl. (Vidakovic 1991). This treatment follows that given in the Flora of Australia (Hill 1998), which describes the 17 species native to Australia (the other 2 are in New Caledonia).

Callitris is proving to be somewhat of a taxonomic problem. Gadek et al. (2000), in a molecular study, placed it within a well-supported monophyletic clade along with Actinostrobus and Neocallitropsis. A molecular study by Pye et al. (2003), which unfortunately did not include all Callitris taxa, placed Neocallitropsis within Callitris (sister to C. sulcata), with Callitris sister to Actinostrobus. Farjon (2005), in an unpublished morphological analysis, found Callitris monophyletic and sister to an Actinostrobus-Neocallitropsis clade. Most recently, a detailed morphological analysis, considering 42 characters for all species in all three genera, found Callitris paraphyletic in a clade with Actinostrobus, sister to Neocallitropsis (Piggin and Bruhl 2010). However, several of the relationships in the cladograms proposed by Piggin and Bruhl are only weakly supported; in fact the only clade supported by a bootstrap percentage above 90% is that of Actinostrobus. Review of this work suggests to me that the close relationship between Callitris, Actinostrobus and Neocallitropsis is well supported and the three taxa could be unified in a single genus. The close relationship between the three species of Actinostrobus is also well supported. Within Callitris there seem to be some well-supported species groups, such as C. endlicheri-C. muelleri-C. oblonga, and there are some intriguing similarities between Neocallitropsis and the two New Caledonian Callitris species, but in general the taxonomic relationships within the genus have not yet been sorted out.

Description

Monoecious, evergreen trees or shrubs. Branches erect, spreading or fastigiate. Bark persistent, hard and compact (fibrous in C. macleayana). Branchlets appearing to consist of triangular or grooved-cylindrical joints owing to the decurrent leaf bases. Adult leaves scale-like, in alternating whorls of 3, decurrent for much of their length; free tip triangular in section and often appressed; dorsal surface rounded or keeled. Juvenile leaves in whorls of 4, triangular in cross-section, basally shortly decurrent below a spreading needle-like upper portion, in some species remaining on mature trees. Male cones ovoid, obovoid, oblong or cylindrical, solitary, paired or clustered at the ends of the branchlets, comprising numerous alternating, trimerous whorls of imbricate scales; each with 2-6 abaxial microsporangia; pollen spherical, not saccate. Female cones solitary or clustered on short lateral branches, comprising 2 whorls of 3 fertile scales with a reduced internode, to form a 6-merous cone (rarely 8 in C. macleayana and C. oblonga); outer whorl of scales often smaller than the inner; fertile scales each with 1-8 erect ovules and subtended by an adnate sterile bract which may form a dorsal protuberance; 10-30 mm diam.; globose to ovoid. Mature cones are persistent or deciduous. Below each scale are 1-8 seeds, oblong, with 1-3 wings (Harden 1990, Vidakovic 1991, Hill 1998). For the 7 species studied (Mehra and Koshoo 1956), 2n=22.

Range

Australia (all States) and New Caledonia; naturalized in USA: Florida (Harden 1990, Wunderlin 1993). Although the genus is widely distributed, many of the species are of very narrow distribution. Callitris forest or woodland forms a dominant vegetation type only in a relatively restricted portion of South Australia, Victoria, New South Wales, and Queensland (see map at left). In this region, the summers are hot and the winters are mild to warm. Rainfall is variable from 400 mm to 600 mm. Stands are generally dominated by an herbaceous understory with few shrubs. Associated tree species include mulga (Acacia aneura), wilga (Geijera spp.), sugarwood (Myoporum spp.) and buloke or belah (Casuarina spp.). Associated shrub species include Eremophila, Dodonaea, chenopods (e.g. Atriplex, Maireana, Sclerolaena) and grasses (e.g. Triodia, Plectrachne, Aristida and Austrostipa). Extensive areas have been cleared for grazing. Large portions of the remaining forest and woodland are included in state forests and other crown reserves in Queensland and New South Wales, where silvicultural and fire management practices are used to foster Callitris in preference to other canopy trees (NLWRA 2001).

Big tree

C. macleayana grows up to 50 m in height and up to 1.5 m in diameter (Vidakovic 1991).

Oldest

Dendrochronology

Some work has been done. See, for example, Searson and Pearson (2001).

Ethnobotany

"A number of the more abundant species have been and still are widely cut for their durable and insect-resistant timber" (Hill 1998). Aboriginal Australians have used different species for diverse purposes, such as oars, spears, glues, and medicines (Christiansen 2000).

Observations

Remarks

Named for the "Greek callos, beautiful, and treis, three, referring to the beauty of the plants and the three-whorled leaves and cone scales" (Wunderlin 1993).

Birds feed on the seeds, and cypress pine jewel beetle larvae feed on the branches and trunks (Grodecki et al. 1996).

Citations

Christiansen, D.L. 2000. Australian cypress. INTAD. http://www.intad.asn.au/materials/wd_cypss.asp, accessed 2002.01.18. This site has quite a variety of information on commercial uses of Callitris wood, lists common names for many of the species, and has several links to photographs.

Garden, J. 1957. A revision of the genus Callitris. Vent. Contr. New South Wales Natl. Herb 2(5): 363-392.

Grodecki, Andy, Sylvia Willie and Matt Deshon. 1996. Queensland tree selector. Online database; these data cited at http://ocean.fit.qut.edu.au/tsm/html/treetext.html, accessed 2002.01.18.

Mehra, P.N. and T.N. Koshoo. 1956. J. Genet. 54: 181-185.

[NLWRA] National Land and Water Resources Audit. 2001. Australian Native Vegetation Assessment 2001. www.anra.gov.au/topics/vegetation/pubs/native_vegetation/nat_veg_veggroups.html, accessed 2010.02.02.

Piggin, J., and J.J. Bruhl. 2010. Phylogeny reconstruction of Callitris Vent. (Cupressaceae) and its allies leads to inclusion of Actinostrobus within Callitris. Australian Systematic Botany 23:69-93.

Pye, M.G., P.A. Gadek, and K.J. Edwards. 2003. Divergence, diversity and species of the Australian Callitris (Cupressaceae) and allied genera: evidence from ITS sequence data. Australian Systematic Botany 16:505–514.

Wunderlin, Richard P. 1993. Cupressaceae. Flora of North America Editorial Committee (eds.): Flora of North America North of Mexico, Vol. 2. Oxford University Press. This document is available online. Go to http://hua.huh.harvard.edu/cgi-bin/Flora/flora.pl?FLORA_ID=12395 and search for "Callitris".