H. martini is a climbing cactus that expands by branching and creating new stems at the base. The latter are green or greyish green and have 5-6 longitudinal ribs, with white and fluffy areolas from which emerge the central and radial spines. The radial spines are short and sparse while the central ones are longer and robust white. This magnificent cactaceae is also known as 'Moonlight cactus' because of its inflorescences that remain open only one night. Its funnel-shaped flowers bloom at night, close to the apex of its long stems and are white with very particular pinkish shades. The flowering period is spring and summer.