The flower of Huernia longituba subsp. longituba grows solitary or in groups of up to three from the base of young stems. In the case of multiple flowers, they open successively. The pedicel or flower stalk is about 1,5 cm in length and hairless.
The corolla is bell-shaped with a tube of about 1,5 cm deep, sometimes more, opening into five lobes with acute tips. The long-tubed huernia would be an apt common name for a species that rightly carries this specific name. The outside surface of the corolla is creamy beige with no hairs and no markings apart from veining. The inside surface is densely covered in tiny and stiffly erect protuberances as well as purple spots. The fleshy protuberances, papilla-like, are conical, becoming smaller towards the lobe tips. The purple spots become darker and denser towards the throat of the flower. The base of the tube is free of spots and projections, being whitish and smooth with transversal purple or red lines. A small secondary tooth occurs at the sinuses, halfway between every pair of lobe tips.
At the base of the flower tube there is a five-lobed outer corona, darkly purple in colour and within it also an inner corona with small, cylindrical, curving lobes (White and Sloane, 1937).