What does it mean that there is no tongue-shaped flower and the flower is barrel-shaped?

Tongue flower, also called Bidens bipinnata, is a panicum miliaceum with an upright stem and a obtuse quadrangle. The lower leaves of the stem are small, rarely pinnately compound, with lobules, and the lobules on both sides are ovoid or ovoid. The head is 8-9 mm in diameter. The involucre base is pubescent, strip-shaped, spoon-shaped, and the upper part is slightly wider. No ligulate flowers, discoid flowers, 5-toothed crowns. Achene is black, strip-shaped, slightly flat, angular, with sparse tuberous protrusions and bristles on the upper part and 3-4 barbs at the top with barbed hairs.

Many provinces in China have production. Born in villages, roadsides and wasteland. Widely distributed in tropical and subtropical regions of Asia and America. It is a common folk herb in China, which has the effects of clearing away heat and toxic materials, removing blood stasis and promoting blood circulation. It is mainly used for treating upper respiratory tract infection, sore throat, acute appendicitis, acute icteric hepatitis, gastroenteritis, rheumatic joint pain and malaria, and externally used for treating furuncle, snake bite and traumatic swelling and pain.