Abstract
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'Hér. (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 nonirrigated plants. This adaptation is believed to play an important role in the species survival during hot summer months.