English is so confusing sometimes!
Spike is shown in the Spanish-English dictionary as the word I'm looking for, but it's not suitable for an American English speaker, who founds "wheat stalk" more suitable. But I find "grain ear" in a web page, which sounds strange to a British English speaker, but appears to be exactly as the word I'm looking for in the Wikipedia, where the word "spike" does not seem to include a reference to wheat.
Such a simple word seems to have a complicated use in English!