Did the very influential (in their time) American firms Dreer's and Bobbink & Atkins simply decide to wind up business and shut down, or were they absorbed by other firms?

It seems strange to me that such companies which were so well known for decades finally seemed to disappear without remark in the rose world (of course, the same thing happened with Moreau-Robert: I've never found any contemporary remark on it shutting down).