Callitris Species Research Articles

Azulenes, Costols and Γ-Lactones from Cypress-Pines (Callitris columellaris, C. glaucophylla and C. intratropica) Distilled Oils and Methanol Extracts

Azulenes, costols and Γ-lactones extracted from the woods of three Australian cypress-pines, Callitris columellaris, C. glaucophylla and C. intratropica, were investigated using GC and GC/MS. Distilled oils and methanol extracts were compared with each other and with a fourth sample of C. glaucophylla from an area outside of its normal range in northern New South Wales (NSW), Australia. The presence of two azulenes (guaiazulene and chamazulene), cadalene, three costols (α-costol, β-costol and Γ-costol), two methyl isocosticate esters, several isokhusenic acids and many Γ-lactones, was determined by GC/MS. Distilled oils contained less Γ-lactones than the extracts. The oil and extract of C. glaucophylla from NSW is different from a comparison sample of the same species. The distilled oil resembles C. glaucophylla but the extract resembles C. intratropica. The results suggest intraspecific as well as interspecific variation in Callitris volatiles. Total acids could be used to distinguish between C. intratropica and other Callitris species

CALLITROID (CALLITRISOID) THICKENING IN CALLITRIS

In softwood tracheids, callitroid thickening is the term given to raised bars located above and below individual bordered pit apertures. Although most well developed in the Australasian genus Callitris, callitroid thickening is reported to be absent from six Callitris species and to vary in its frequency and prominence. An SEM study of callitroid thickening was carried out on multiple wood samples of each Callitris species, taken from trees growing in the wild. The aims of the study were to determine the occurrence, frequency, visual prominence and morphology of callitroid thickening in all Callitris species and to determine whether it could be used taxonomically. Callitroid thickening was found in all (19) species of the genus, in contrast to previous reports of its absence in some species. In general, callitroid thickening occurred at higher frequencies and was more prominent in species from dry habitats than in those from wet habitats. The frequency of thickening varied between and within samples and, for example, it was always more frequent on pits in narrow rather than in wide tracheids. Callitroid thickening varied in its morphology, and types consisting of one to four bars, extending completely or only partially across the inner radial wall of the tracheid, were observed. Thickening on tracheid-ray pits within cross fields occurred in all species, and with similar frequency and morphology to thickening of bordered pits. Our findings suggest that frequency of callitroid thickening is useful taxonomically in separating four groups of Callitris species and in assisting in the identification of certain individual species.

Direct seeding of native trees and shrubs in low rainfall areas and on non-wetting sands in South Australia

Seeds of common endemic species of Acacia, Callitris, Eucalyptus and Melaleuca were sown at 12 sites in Southern Australia in 1994 and 1995 to determine the role of soil stabilisers, fertilisers, time of seeding, herbicides, ripping and soil preparation with a V-blade or a disc in improving the reliability of direct seeding in Mediterranean type climates with low rainfall. Rainfall in 1994 was below average with 140 mm at the northern sites (55% of the average) and 300 mm at the southern sites (74% of the average) and only Acacia was successful with at least 3 plants/10 m present at the end of spring at eight sites and a survival rate after the first summer of 43%. In 1995 at least 3 plants/10 m of Acacia and Eucalyptus spp. were present at the end of spring at eight sites, with at least 3 plants/10 m of Melaleuca at six sites and at least 3 plants/10 m of Callitris at only three sites. Melaleuca had the highest overall survival rate at the end of summer with 52% compared to Acacia 42%, Eucalyptus 41% and Callitris 29%. Sowing two to three weeks after the opening rains (May at most sites) with good weed control gave the best results. Plant survival over the summer was reduced by 40% where weeds were not controlled by a herbicide. Ripping or fertiliser did not improve success. Ground preparation with an 80 cm wide V-blade generally produced better results than using a 25 cm wide disc except for Melaleuca. The effect of bitumen was variable in the trials, but appeared to be beneficial on wind eroded sites. The results indicate that direct seeding of trees and shrubs can be carried out in Mediterranean type climates with 250 to 425 mm average annual rainfall including on soils that are water repellent. This technology could be used for large scale revegetation in areas of the world with low rainfall Mediterranean type climates that have been largely denuded of trees and shrubs.

Morphology of Warts in the Tracheids of Cypress Pine (Callitris Vent.)

A high-resolution SEM examination of the warty layer in tracheids of the Australasian softwood genus Callitris Vent. has revea1ed that warts in 12 of the 16 species have variable, complex morphology and nodule-like projections, giving them a 'nodulated' or 'branched' appearance similar to those described for certain hardwoods. Pairs of warts were occasionally anastomosed. Warts could be categorised into two types; large and no dulated, or small and hemispherical. In the four Callitris species native to high rainfall environments, warts were invariably of the latter type and were morphologically distinct from the mixed populations of small hemispherical and large nodulated warts found in species from dry habitats. This suggests that large nodulated warts are of adaptive value in waterstress conditions. Wart morphology was useful as an indicator of Callitris species although intra-specific variation limited the accuracy of diagnosis.

The Distributions, Dynamics and Ecological Differentiation of Callitris Species in Tasmania

Callitris oblonga and C. rhomboidea are the only gymnosperms found in the drier parts of Tasmania, where they have marginally overlapping and internally highly disjunct distributions. There is virtually no overlap in their periods of pollen production. Consequently, apparent hybrids are extremely rare. C. oblonga, a Tasmanian endemic, is largely confined to riverine vegetation in the dry cast and centre of the State. C. rhomboidea occupies well drained sites along parts of the east coast, where it is capable of regenerating continuously without major disturbance, or phasically after fire or other major devegetating events. Areas topographically, edaphically and climatically well within the ranges of the two species have no populations of either suggesting that neither species occupies its potential range in Tasmania. Morphological and physiological characters, such as form and frost resistance, reflect the local and regional environment occupied by the two species.

Pitting of Transfusion Tracheids in Cupressaceae

The morphology and development of the circular bordered pits on the transfusion tracheids in the leaves of Callitris muelleri are described from light microscopy of semithin sections and SEM studies of cut surfaces. Two parallel bars of thickening develop on the pit border either side of the aperture, and trabecula-like outgrowths develop into the cell lumen from the centre of each bar. These outgrowths are often contorted and may anastomose with the wall or each other. Development is arrested at the barred stage in occasional pits, and both 'barred' and 'trabeculate' pits may occur in the one cell. 'Trabeculate-pitting' occurs in all species of Callitris and Actinostrobus, and was also observed in species of Cupressus and Juniperus. Previous reports of outgrowths on pits in several species of the last two genera suggest that the trabeculate pit is characteristic of both. 'Barred pits' occur in Widdringtonia cupressoides and Catocedrus decurrens. Unadorned circular bordered pits are characteristic of Diselma archeri, and have previously been reported in a range of genera in the family. These three types of pit are considered to represent an evolutionary transformation series in which the last type is plesiomorphic. The occurrence of the apomorphic conditions in both northern and southern hemi- sphere genera does not fit well with the present taxonomy of the family. The probable adaptive significance of the trabeculate pit is discussed.

Amentoflavones from Callitris species

The biflavonoid patterns of the leaves of five species of Callitris are characterized as amentoflavone based derivatives only. This contrasts markedly with the diversity of biflavones reported for northern genera of the Cupressaceae.

Modified axillary branching in species of the fossil genus Frenelopsis: a new phenomenon among conifers

Shoots of the fossil species Frenelopsis alata (K. Feistmantel) Knobloch (Cheirolopidiaceae) from the Cenomanian of Bohemia and Portugal demonstrate a type of branching not hitherto reported among conifers. It has been interpreted as a modification of conventional axillary branching on the basis of detailed observations on external morphology with the help of comparative studies on living species of the family Cupressaceae (e.g., Callitris species) and other fossils of frenelopsid affinity. The probable nature of the growth pattern of the shoot is discussed.

On a new species of Callitris from eastern Australia

On a new species of Callitris from eastern Australia