Stains for Strands in Sieve Tubes

Abstract

Two very simple procedures give a staining-fixation of the so-called “strands” as well as portions of the sieve plates of sieve tubes of various broad-leaved deciduous trees. One procedure consists of placing hand-made sections (radial or tangential) of inner bark for 5 min in a 0.2% solution of ponceau S in 3% trichloroacetic acid, then soaking 5 min in 5% acetic acid. A second procedure consists of placing sections in 0.001% nigrosin in 2% acetic acid for approximately 15 hr, then washing briefly in distilled water. In the former procedure, strands, sieve plates, and what appears to be plasmalemma, appear reddish or pink, while cell walls do not stain. In the latter, strands and sieve plates appear bluish but phloem cell walls also become bluish, although xylem cell walls usually remain unstained.