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.
About this Author
Bobbie Brewer has been writing since 1990. Her work has appeared in publications and on Web sites including Garden Guides and Trails. Brewer is an international traveler, outdoors enthusiast and has been gardening since 1991. She has a Bachelor of Arts in English from California State University, Sacramento.