Internally, the axile placentation and six locules conform to Lagerstroemia morphology but these features are not limited to the genus or to the Lythraceae.
The extinct Minsterocarpum alatum Reid and Chandler (1933) from early Eocene beds at Sheppey, England is a four to six-loculed capsule, 16-22 mm long, with axile placentation and numerous seeds arranged in two rows in each locule.
Numerous seeds from anatropous ovules cover the elongated axile placenta.
Remains of fruits are minimal, consisting merely of an axile placenta with numerous crowded, attached seeds.
The gynoecium is superior, with a simple style and an enlarged, somewhat elongate stigma; the ovary is distinctly stipitate and free of an encircling nectary; six to eight locules each enclose 14 to 20 anatropous ovules in two rows on an axile placenta (Chitaley, 1955).
Ovary 5-locular, with axile placentation and many ovules per locule, superior; style impressed, short to quite long; stigma usually peltate, sometimes also lobed.
Ovary (4-)5(-8)-locular, with axile to parietal placentation and many ovules per locule, superior; style usually impressed, little longer than ovary; stigma barely expanded, rarely lobed.
Ovary 5-locular, with axile and partly intruded parietal placentation, many ovules per locule, superior; style impressed; stigma barely expanded.
Ovary 4-10-locular, with axile placentation and only 1 to few ovules per locule, superior, sometimes with fleshy papillae; style continuous with the ovary; stigma truncate.
Ovary (4-)5-locular, with axile placentation, superior; style impressed; stigma truncate.
Cronquist (1981) maintained that, in combination, its unique leaves, imbricate corolla lobes, and bilocular ovary with axile placentation make the Saccifoliaceae incongruous in the Gentianaceae.
Gynoecium 2(-3-9)-merous, usually bicarpellate, syncarpous, inferior, rarely semi-inferior (Synaptantha) or superior (Gaertnera and Pagamea); ovary with as many locules as carpels (in which case placentation is axile or a derivative), seldom unilocular (Gardenia) (in which case placentation is parietal) or pseudomonomerous (Theligonum): style usually one and slender or styles free (Galium), rarely basilateral (Theligonum), or even missing (Tetralopha): stigma capitate or lobed: ovules 1 to many in each locule; anatropous to hemitropous, or campylotropus (Theligonum); solitary, basal, without integumentary tapetum.