Day Two (continued):  Upon careful examination, Rosebud realized that the xylem-removed stalk had an unnatural, somewhat nuclear green, glow (from the colored water) and discovered that the teacher setting up the lab had NOT remove all of the xylem from the xylem-removed stalk.  This explained why the xylem intact/no water stalk was more wilted than the xylem-removed stalk.

Day Three:  WOW!  The three stalks of celery looked exactly like they were supposed to (well, they were supposed to look like they looked on day three by day two, but the lab teacher had mistakenly purchased delayed celery rather than on-time celery and that impacted the outcome of the
experiment).  The xylem-removed stalk was significantly more wilted and much less firm than the xylem-intact/no water stalk.  The xylem-intact/water stalk was just as fresh and crisp as it had been on day one (just significantly more blue).