What Type of Stem Does a Sunflower Plant Have?
A seedling sunflower's stem, or stalk, is made up of the Epicotyl, which is just above the first leaves (the cotyledons) of the plant, and the hypocotyl, which is below. The woody mature stems are sturdy, round, and often branch out to hold additional blooms depending on the sunflower variety.
A young sunflower's flower head faces the sun to receive the sunlight it needs for photosynthesis. Heliotropism is the term for a plant's ability to follow the sun. In early morning, plant cells on the western side of the stem begin to grow and elongate, causing the sunflower bloom to tilt toward the sun. As the sun moves across the sky, the cells on the stem's side that is opposite the sun elongate, keeping the flower head facing the sun. The sunflower doesn't stop tracking the sun after the sun dips below the horizon. The sunflower's bloom continues to move until it faces east, put the flower head in position to catch the sun's morning rays. For example, plant the sunflower on your yard's western or northern side.