Aptosimum albomarginatum flowers

The sessile to nearly stalkless, blue to blue-purple flowers of Aptosimum albomarginatum are tubular and two-lipped, borne from leaf axils. The flowers are comparatively large among those of Aptosimum species.

The narrow-lobed, acutely pointed calyx is about 7 mm long with leaf-like bracts below it.

The corolla is pale blue to blue purple, its tube up to 2,5 cm long. This tube that narrows to the base is hairy and dark-veined on its outside. The inside of the corolla tube may be paler blue, sometimes with white and black markings around the oblique mouth. The five spreading corolla lobes are short and rounded to ovate.

The four stamens grow in unequal pairs, the lower, shorter ones sterile. The hairy style is exserted. Flowering happens throughout the year when conditions are favourable, presumably moisture and temperature related, peaking around the end of summer.

The fruit is an obovoid, grey capsule up to 6 mm long. There are prominent, parallel nerves along the capsule sides. The fruits are closely pressed to the stem (Van Rooyen and Van Rooyen, 2019; iNaturalist; http://powo.science.kew.org).