DENDROLOGY

Detailed explanation-1: -When do sunflowers bloom? Annual sunflowers bloom during summer and into autumn. Sow new plants every few weeks and you’ll enjoy non-stop flowers until the first frost. Perennial sunflowers bloom for a period of 8-12 weeks with some beginning as early as July and others finishing as late as October.

Detailed explanation-2: -What is often called the “flower” of the sunflower is actually a “flower head” (pseudanthium), 7.5–12.5 centimetres (3–5 in) wide, of numerous small individual five-petaled flowers ("florets"). The outer flowers, which resemble petals, are called ray flowers.

Detailed explanation-3: -sunflower, (genus Helianthus), genus of nearly 70 species of herbaceous plants of the aster family (Asteraceae). Sunflowers are native primarily to North and South America, and some species are cultivated as ornamentals for their spectacular size and flower heads and for their edible seeds.