Mammoth Sunflower Seeds Helianthus annuus are a tall growing annual flower variety known for producing large bright yellow blooms and strong upright stems This heirloom sunflower variety develops broad flower heads with vibrant petals that create striking seasonal displays The plants grow vigorously and form tall stalks that support large blossoms during warm seasonal conditions This sunflower variety is valued for its impressive height and bold floral appearance making it a widely recognized flowering plant for seasonal ornamental cultivation