Complex sentence: The flower of "Heterosmilax" is fused into a deep bottle-shaped tube containing prominent nectaries and its stamens are connected at the bottom, whereas flowers of "Smilax" are typically small with unfused floral parts.
Split into simpler sentences: The flower of "Heterosmilax" is fused into a deep bottle-shaped tube containing prominent nectaries, its stamens are also connected at the bottom. Whereas flowers of "Smilax" are typically small with unfused floral parts.