The haustorium of Harveya causes the inner tissues of the host root to grow larger, and thus the two plants become closely connected. These parasites have large, sunken stomata that help set up fast transpiration. This aids the suction of nutrients from the host root. Many specimens of H. squamosa have an extensive underground rhizome. This may give it an advantage for living in loose and shifting sandy soil (Randle 2006). One herbarium specimen records that some flowers had been eaten by caterpillars.

A common feature of the genus Harveya was noted by Visser (1981). "One anther cell of each stamen is sterile and transformed into a spur to aid the shedding of pollen before the stigma blocks the way". Presumably the pollinator, by touching the spur, will help shake pollen out of the anther cell. The downward curve of the style leads to the stigma blocking the entrance to the corolla tube. This aids transfer of pollen from the pollinator to the stigma, as the pollinator pushes past.

Visser (1981) suggested that pollination of this Harveya is by birds because of the narrowly tubular, orange or red flowers, copious nectar and lack of scent. Further to this, the flowers are usually clearly visible, out in the open, not being hidden by other plants. However, there are no definite records of pollinators for this species. Perhaps ants, mice or sengis (elephant-shrews) are involved. The last two may not be very likely as the flowers do not seem to get damaged. In Mpumalanga, flowers of another root parasite, Cytinus visseri, are visited by other species of these small animals and are often broken slantwise (Smithies & Burgoyne, 2010). However, the latest paper about mouse and sengi pollination (Weston 2011) noted that the Cape species of these animals do not damage the flowers of Whiteheadia bifolia.