Stamens united by their anthers into a ring or tube.
Flowers in an involucrate head. [Compositæ], [230]
Flowers separate, not involucrate; corolla irregular. [Lobeliaceæ], [305]
Stamens separate, free from the corolla or nearly so, as many as its lobes; stipules none; juice milky. [Campanulaceæ], [307]
Stamens separate, inserted on the corolla,
One to three, always fewer than the corolla-lobes. [Valerianaceæ], [228]
Four or five; leaves opposite or whorled.
Ovary 1-celled; flowers in a dense involucrate head. [Dipsaceæ], [229]
Ovary 2–5-celled.
Leaves whorled and without stipules. [Rubiaceæ], [222]