It differs from most other Otholobium species by the calyx that continues to grow after flowering and the leaf that consists of just one leaflet.

Charles Stirton and A. Muthama Muasya considered it sufficiently different from its relatives, described it in 2017, and called it Otholobium accrescens.

[2] Otholobium accrescens is a small, upright, largely herbaceous subshrub of up 10–60 cm (3.9–23.6 in) high, that resprouts from the underground rootstock, after a fire destroyed the above ground biomass, by growing up to 3 stems at an interval from one another.

[2] The open inflorescences emerge on 70–110 mm (2.8–4.3 in) long peduncles (4–5 times longer than the subtending leaf) from the axils of the lower leaves.

The four other teeth are lance-shaped, with the edges approximately parallel towards the tube and both lobes at the upside of the flower are fused further than rest.

The blade of the wing is adorned with about 35 irregular ridges in indistinct rows and has one lobe or auricle facing the base.

At the tip the ovary extends into a forward sloping style that is thickened at the place where it curves upwards about 2–3 mm from its end.

[2] Otholobium accrescens differs from O. afrum and O. fumeum, which are shrubs of up to 1.5 m (4 ft 11 in) high (not a plant of 10 to 60 cm, only woody at the base), with clover-like leaves consisting of 3 flat leaflets (not with only one leaflet), and sepals shorter than the petals (not equally long sepals and petals).

Specimens of this species may live for over 50 years and the plants resproute from the underground rootstock after fire has destroyed the biomass above the ground.