About some flowers, my books said "red (or purple, or blue), sometimes
white". BRBR
Are they albinos ? BRBR

Yes. In some plants, I know it is true in orchids, there are two or three steps
in the conversion of sugar to anthocyanin, involving certain enzymes. If there
is a mutation which disables any one of the enzymes in the pathway, the result
is white flowers.

Do the seeds give another white ? BRBR

Generally yes. The gene which produces the defective or missing enzyme is
usually recessive. If you self pollinate a plant with wnite flowers, you can
expect all white progeny. If you cross two white flowers, you may or may not
get all white offspring, depending on whether the genes match up.

I think they appear at the end of the flowering period ? BRBR

Not sure what you mean. I don't know of any plants which produce colored
flowers at the beginning of their flowering season and white flowers later on.
Iris,
Central NY, Zone 5a, Sunset Zone 40
"If we see light at the end of the tunnel, It's the light of the oncoming
train."
Robert Lowell (1917-1977)