Concept:
Colchicum seeds contain an important alkaloid called colchicine.
Step 1: Colchicine is the active constituent of colchicum.
Step 2: It is used in gout and inflammatory conditions.
Step 3: Its anti-rheumatic and anti-inflammatory action is due to colchicine.
Step 4: Vinblastine, reserpine, and podophyllotoxin belong to different plant sources.
\[
\boxed{\text{Colchicine}}
\]