I can't speak for Ramon, but your original question what "Who are the parents?" My first guess was longifolium because the flowers looks a lot like Sorcerer's Apprentice and Urgandiae. But then you posted a photo of your questioned flower and your Sorcerer's Apprentice side-by-side, showing the small flower by comparison. When Leo noted that the tag was probably right, lindleyanum x caricinum, I thought that made sense, but offered that sargentianum also offers smaller flowers. Were it mine, I'd go with what the tag says.