It is amazing what you learn while doing your homework on 365project.org
"Most dictionaries endorse both forms. "Crocuses" is the most common form, but the Latin masculine plural "croci" may be used as well. "Crocus" is one of several words that can take a Latin masculine plural, even though they were originally Greek words. In Greek, "octopus, "cactus" and "syllabus" were "oktopous," "kaktos" and "syllubos," respectively, and their plurals may be rendered as "octopi," "cacti" and "syllabi."
It's also acceptable to pluralize "crocus" by simply using its singular form, "crocus." We often use such "zero plurals" with animals as well, especially if they're found in groups - "deer," "sheep," "elk," "buffalo," "salmon," "trout."
And the zero plural is not uncommon with plants. Just as we might speak of a patch of "crocus," we speak of a forest full of "maple," "oak" and "birch.""
