The sunflower seed is the fruit of the sunflower (Helianthus annuus). The term "sunflower seed" is actually a misnomer when applied to the seed in its pericarp (hull). Botanically speaking, it is a cypsela. When dehulled, the edible remainder is called the sunflower kernel or heart.There are three types of commonly used sunflower seeds: linoleic (most common), high oleic, and NuSun. Each variety has its own unique levels of monounsaturated, saturated, and polyunsaturated fats.