Does this mean its not a female?

My friend asked me if I had ever seen anything like what he was experiencing. The plants have been into flowering for several weeks now and most of the plants that are obvious females have very pronounced white hairs protruding from the calyxes. There are a few however that are in question. They have absolutely no sign of any male sacks and in fact the colas look very much like the others however they arent white. They seem to remain green looking. Is this the result of a nutrient lockout? The plants have been on a water onyl diet for a week and a half with only one fert. feeding in the week before that. Any input?

The only way to give any type of accurate advice on your particular problem would be to see a pic?

yes yes, we are going to need pictures