The foliar characters in Callitris (Callitroideae, Cupressaceae s. str.) and their evolutionary and ecological significance

Abstract

The foliar shift from juvenile needle leaves to the mature scale leaves was investigated in five Callitris species. Their habitats range from rainforest to the semi‐arid. In C. macleayana from the most mesic environment the change from needle to scale leaves is variable and juvenile leave are even retained on mature trees. In the other four species there is a rapid change in size and structure to scale leaves. Anatomically the photosynthetic tissue is condensed and stomatal area is limited compared to species with conventional leaves. A hypodermis is most prominent on the abaxial side of the leaves and may play a role in protection from high solar radiation as most species grow in high light areas. While stomata in the four taxa from wet or moderate rainfall areas are freely exposed, those of C. gracilis from semi‐arid habitats are well protected in longitudinal furrows between the decurrent leaves. The reduced leaf area of all species allows close association between the water‐conducting xylem and the stomata that will facilitate rapid leaf conductance. This links with the anisohydric physiology of the genus and the shallow rooting that can take advantage of brief rainfall events for species in arid climates.

Water storage and transport in leaves of vesselless trees in the temperate rainforest of south-central Chile

“…It does not have reticulate venation, however it has a well-developed transfusion tissue and ATT. Transfusion tissue accompanying the midvein is common in gymnosperms and undoubtedly facilitates water conduction to the adjacent mesophyll cells (Frank 1864;Lederer 1955;Esau 1977;Hu & Yao 1981;Dӧrken 2013;Dӧrken & Parsons 2016;Dӧrken et al 2019;Moreau et al 2021). Transfusion tissue in the leaves of P. saligna consists of multiple highly specialized tracheids, the pitting pattern of which is similar to wood tracheids.…”

Comparative petioler anatomy of tribe Mentheae subfamily Nepetoideae, Lamiaceae from Pakistan

“…The number of vascular bundles in the petiole is different from that in the base of the leaf of R. discoid (Sacramento Silva, Leite, & Roque, ). The use of anatomical methods in taxonomic research cannot be overstated (Dörken, Ladd, & Parsons, ; Matias et al., ). The taxa can be characterized accurately through a comparative analysis of the various petiolar characters (Anu & Dan, ).…”