Nasturtium vs. Nasturtian

The English seem to have a problem when referring to a pretty trailing garden plant with bright yellow or red flowers 1 that grows in their gardens... When I was little we were wont to say "Nasturtium", until our grandmother corrected us: "it's Nasturtian!" Indeed the OED records the usage of "Nasturtium" as "improp.", improper that is.

So, you might ask, if "Nasturtium" is wrong, what is it? The OED says it is "kinds of pungent-tasting cruciferous plants including watercress", but this little anecdotal conversation between J.R.R. Tolkien and his college gardener sets the record straight:

I consulted the college gardener to this effect: 'What do you call these things, gardener?"

"I calls them tropaeolum, sir."

"But, when you're just talking to dons?"

"I says nasturtians, sir."

"Not nasturtium?"

"No, sir; that's watercress."

And that seems to be the fact of botanical nomenclature...2

Tolkien, a professor of English himself, dug his toes in so about his publishers silently mis-correcting his words (e.g. "elfin for elven; farther for further; try to say for try and say and so on"3) that not proving that he was talking about "Indian Cress" (yes, it's the one with pretty flowers!) and not ordinary watercress was out of the question.

Indeed our own Webster is quite wrong in his second definition of "nasturtium":


1 The Concise Oxford Dictionary, 1964 ed., p. 801
2 The Letters of JRR Tolkien, 1995 ed.: no. 148, p. 183
3 ibidem