What it says
The gladiolus speaks of strength of character and fidelity. The name comes from gladius, the Roman short sword — the gladiator's — after the shape of its leaves, straight and tapered.
The spike can exceed a metre and opens from the bottom upward over several days. It is a flower that unfolds in time.
Where the reputation comes from
In France it has been used so heavily in funeral work that it became unofferable otherwise. That is neither ancient nor universal: elsewhere it remains an ordinary garden and vase flower, and its verticality makes it one of the few able to structure an arrangement without foliage.
A dominant use erases a symbol. The gladiolus speaks of strength; it speaks of mourning only because it was put there. Nothing obliges anyone to leave it.
Keeping it upright
The spike is heavy and bends toward light. Use a tall narrow vase filled to a third, and give it a quarter turn daily. Pinch the terminal bud: the plant then concentrates on the flowers already formed and the spike lengthens less.
Cut at an angle, change the water every two days, and remove spent flowers from the bottom as you go — they spoil the whole while the top is still unopened.
our piece on flower symbolism places the gladiolus among the flowers of bearing and verticality.