Impact of water stress on the sapwood anatomy and functional morphology of Calligonum comosum

This investigation reports the impact of water stress on some anatomical traits of sapwood and other functional morphological features of green assimilatory shoots of Calligonum comosum L'Her. (Erta), a good source of fuel wood. The major findings of the study are that in this species drought makes for: a) narrower vessels both in earlywood and latewood, b) thicker vessel walls, c) longer vessel elements and fibers, d) a higher frequency of small latewood vessels and a lower frequency of large earlywood vessels, e) narrower growth rings, f) a lower total fraction of vessels per xylem area, g) higher wood density, h) narrower depth of conducting phloem, i) higher specific mass of green photosynthetic shoots, and j) a lower chlorophyll content. Extremely narrow vessels arranged in radial files in latewood were recognized having 40% increased volume fraction in non-irrigated plants. This adaptation is believed to play an important role in the species survival during hot summer months.