Stephen Hopper described the subspecies remanens as a short-leaved shrubby form found in the coastal sands below granite outcrops in the Walpole-Nornalup National Park.

However, George does not feel this form warrants taxonomic recognition as it lies within the normal variability of the species and there was no clear distinction between it and the other populations of B. seminuda.

The type specimen of Banksia seminuda was collected on 15 May 1973 in Nanga Brook, Western Australia, by Alex George,[4] who described it in 1981 as a subspecies of B. littoralis.

In 1984, botanist Barbara Rye of the Western Australian Herbarium noted that the two species did not interbreed when they occurred in stands together in the Two Peoples Bay region.

Under George's taxonomic arrangement of Banksia, B. seminuda's taxonomic placement may be summarised as follows:[3] A 2013 molecular study by Marcel Cardillo and colleagues using chloroplast DNA and combining it with earlier results found that B. seminuda was sister to a combined lineage that gave rise to B. quercifolia and B. oreophila.

Hopper noted some intermediate stands with the usual tree forms at Broke Inlet and Coalmine Beach, and at Boggy Lake, around 600 m northwest of the summit of Mt Hopkins.

[7] George does not feel this form warrants taxonomic recognition as it lies within the normal variability of the species and there was no clear distinction between it and the other populations of B. seminuda.

The short-leaved shrubby form is found in deep coastal sands below granite outcrops in the Walpole-Nornalup National Park.

It also grows in thickets of vegetation next to granite outcrops, associated with granite banksia (Banksia verticillata), Walpole wax (Chamelaucium floriferum), Taxandria marginata, heart-leaved poison (Gastrolobium bilobum), myrtle wattle (Acacia myrtifolia) and sticky tailflower (Anthocercis viscosa).