Might be I.germanica

Look up pictures of "Crimson King". Mine does multiply like rabbits :-))

30 inches puts a bearded iris into the tall classification. Height may vary year to year. If yours is consistently 30 inches or more ............... maybe not Crimson K.

Here's an in depth article on that iris.
http://historiciris.blogspot.com/2012/04/historic-iris-germanica-crimson-king.html

Irisgal--thank you very much for the ID and the link. My iris are usually a couple inches shorter than 30"--I gave the height of the tallest one. The info in the link about reblooming is especially interesting, as a couple of mine have tried to re-bloom, but have been cut short by winter. I will forward the link to my friend who gave me the iris--she will also be very interested, and would also want to thank you.