16. Gentianaceæ—Herbs with opposite entire leaves and solitary regular flowers. Calyx 4- to 10-lobed. Corolla 4- to 10-lobed. Stamens 4 to 10, alternate with the lobes of the corolla. Ovary 1- or 2-celled. Fruit a capsule.
2. Ovary Inferior and Stamens on the Corolla
17. Compositæ—Herbs with flowers (generally yellow or white) collected into compact heads. Calyx absent or represented by a pappus. Corolla tubular or ligulate. Stamens 4 or 5.
b. Corolla Polypetalous
1. Stamens Perigynous (around the Ovary), or Epigynous (upon the Ovary)
18. Umbelliferæ—Herbs with (generally) compound leaves, and small, white, umbelled flowers. Sepals (if present) 5. Petals 5. Stamens 5. Ovary inferior. Fruit of two adhering carpels.
19. Illecebraceæ—Small herbs with sessile, entire leaves, and small flowers. Sepals 4 or 5. Petals 4 or 5 or absent. Stamens 1 to 5. Ovary superior.
20. Tamariscaceæ—Shrub with small, scale-like leaves, and lateral spikes of small regular flowers. Sepals 4 or 5. Petals 4 or 5. Stamens 4 or more.
21. Leguminosæ—Herbs or shrubs with alternate, stipuled, pinnate or ternate leaves, sometimes tendrilled, and irregular flowers. Sepals 4 or 5. Corolla of 5 petals, papilionaceous (butterfly-like). Stamens usually 10. Ovary superior. Fruit a pod.
2. Stamens Hypogynous (attached below the Ovary)