Which plant holds yellow flowers but does not appear showy or fully open?

The plant characterized by holding yellow flowers that do not appear showy or fully open is indeed spatterdock. This aquatic plant typically features distinctive yellow flowers that emerge from the water's surface, but they do not have the expansive, fully open blooms that some other aquatic plants, such as the white waterlily or American lotus, display.

Spatterdock, which is also known as Nuphar lutea, has a more subdued presentation, as its flowers are often somewhat closed and leaf-like, making them less visually striking compared to more vibrant flowering plants. This is in contrast to the American lotus, which produces large, showy flowers, and the white waterlily, known for its widely opened blossoms that float gracefully on the surface of the water. Water lettuce, while also an aquatic plant, is known for its rosettes of green leaves rather than flowers, making it an unlikely choice in this context.

Understanding the physical characteristics of these plants, especially their flowering habits, helps in identifying them effectively in aquatic ecosystems.