Dahlias are annual blooming plants, with mostly tuberous roots. While some have herbaceous stems, others have stems which signify in the absence of secondary tissue and re sprout following winter dormancy, allowing further seasons of growth.As a member of the Asteraceae the flower head is actually a composite (hence the older name Compositae) with both central disc florets and surrounding ray florets. Each floret is a flower in its own right, but is often incorrectly described as a petal, particularly by horticulturists. The modern name Asteraceae refers to the appearance of a star with surrounding rays.