Stem anatomy of the dwarf subshrub Cressa cretica L. (Convolvulaceae)

摘要: Stem anatomy and development of medullary phloem are studied in the dwarf subshrub Cressa cretica L. (Convolvulaceae). The family Convolvulaceae is dominated by vines or woody climbers, which characterized presence successive cambia, medullary- included phloem, internal cambium fibriform vessels. main stems not winding C. shows (internal) vessels, whereas cambia lacking. However, vessels an unique feature so far has been reported only climbing members family. Medullary develops from peri-medullary cells after initiation secondary growth completely occupies pith region fully grown mature plants. In young stems, cortex wide formed radial files tightly packed small large without intercellular air spaces. thick cortical become compressed due to pressure developed expansion xylem, a actually common halophytes. stem diameter increases activity single ring vascular cambium. xylem composed (both fibriform), fibres, axial parenchyma uni-seriate rays. consists sieve elements, companion cells, ray cells. consequence, shares anatomical characteristics both non-climbing members. structure correlated with habit comparable that other Convolvulaceae.