Posted: 17/02/2017 at 20:01
All those are cultivars (cultivated varieties) of one species, Ilex aquifolium, the native English holly. Any female can be pollinated by any male.
Yes, quite ridiculous, Golden King is female and Silver Queen is male., Once a name has been given it stays. Who knows how that happened?
Generally you will find those for sale are sold as either male or female. If not, they are probably seed raised and you won't know which they are til they flower so don't buy them.
They are not crossing, one is pollinating the other.
all plants need male and female parts of flower to produce seed. On some plants the male and female parts are both in the same flower. In others (holly is one) male parts are found in the flowers of some bushes and females in other bushes, never both on one.
Look up dioecious and monoecious if you're interested.