A Canna yellow plant, often called a Canna lily, features vibrant yellow flowers on tall stalks, typically with large, broad green leaves. Wikipedia describes the flowers as having erect spikes and the leaves as being ovoid-shaped and branching. The flowers are known for their large, showy petals, and the plant generally has a medium height. 

Here's a more detailed breakdown: 

Flowers:

Canna yellow flowers are typically a bright, sunny yellow, sometimes with red spots or markings. They are borne on upright spikes that rise above the foliage.

Leaves:

The leaves are large and broad, with an ovoid (egg-like) shape. They are typically green, providing a lush backdrop for the bright flowers.

Size:

Canna yellow plants are generally medium in height, making them suitable for various garden settings.

Other Characteristics:

The plant has a branching habit, meaning it grows in multiple directions from the central stem. The flowers are also self-cleaning, which means they naturally shed spent blooms.