It was several years since I saw it, so I'm unclear on some details. However, the short description is that it blooms in a manner that resembles a sparkler (https://en.wikipedia.org/wiki/Sparkler).
The stalk is very tall and thick. It was at least chest height to me or perhaps just below head height. I'm 187 cm (6'1) tall. The shaft is barren, without any leaves. The only leaves were at ground level, and they were pretty large.
On top of the stalk, the flower buds grow in a manner that resembles a corn cob. The buds start out a dark purple and when they start to bloom they go through pink and then orange before it fully blooms into a vibrant yellow. The individual flowers are bell-shaped. After a brief blooming period, they shrink back into orange and then wilts into brown.
While beautiful, the colours truly stand out due to the manner in which these flowers bloom. They don't all bloom at once, rather the "cob" starts blooming from the top and the blooming moves downward. However, the blooming period for each row of flowers is very short, so the top has wilted long before the bottom has even started to bloom. This makes the plant look like an extremely slow-burning sparkler.
I think I saw it blooming around July-August in southern Sweden. It took it multiple weeks to bloom through all its flowers. It was a truly impressive sight as I observed it every night as I worked with newspaper deliveries at the time.