Barry Jones' autobiography: Note on title

I am reading Barry Jones: A thinking reed and enjoying it. (Reviews here and here.)

The title is taken the "man is a thinking reed" quote from philosopher Blaise Pascal's Pensées.

The original:

L'homme est un roseau, le plus faible de la nature, mais c'est un roseau pensant. Il ne faut pas que l'univers entier s'arme pour l'écraser : une vapeur, une goutte d'eau suffit pour le tuer. Mais quand l’univers l’écraserait, l’homme serait encore plus noble que ce qui le tue, puisqu’il sait qu’il meurt et l’avantage que l’univers a sur lui. L’univers n’en sait rien.
Transition 5 (Laf. 200, Sel. 231). H3.

Barry Jones' preferred English version:

“Man is but a reed, the feeblest in nature; but he is a thinking reed. There is no need for the whole universe to take up arms to crush him. A vapour or a drop of water is enough to kill him. But even if the universe were to crush him, man would still be nobler than his killer, for he knows that he is dying and that the universe has the advantage over him. The universe knows nothing of this.”

According to the Philosophy & Philosophers website the "man is a thinking reed" quote is the most famous of French philosopher Blaise Pascal's Pensées.

While there are plenty of online discussions on interpretations of what Pascal means, I must say that I don't see quite why Pascal chose the word 'roseau' which his translators have translated, naturally enough, as 'reed'.