The trunk is usually between 2–4 dm in diameter, and covered by a thick grayish brown bark that acts as a buffer.

Young branches have few flat-lying pale unicellular T-hairs, while the peduncles, pedicels, sepals and petals are thickly covered in such hairs, giving them a felty look.

The somewhat fleshy and distinctly leathery simple leaf blades are yellowish to dark green on top and pale green beneath and measure 6-16 × 1–4 cm, are lanceolate to elliptic in shape, while the widest point may be at or beyond midlength, with a pointy tip, and the edges are coarsely serrated.

Flower buds are formed in March and April and these open from October to the end of December varying according to location and altitude.

Each flower is hermaphrodite, starsymmetric, 21⁄2—31⁄2 cm in diameter and produces copious amounts of nectar, but apparently does not emit a scent.

The five petals are overlapping in the bud, white, felty, spoon-shaped with a narrow base (or claw).

Each space contains two shiny black seeds that are shaped like a slightly curved tear drop of 6×3 mm, and are partly covered by a conspicuous scarlet aril that acts as a visual and tactile cue for birds to locate the seeds.

After genetic analysis showed that Ixerba was not very much related to either Roussea or Brexia, it was placed in the monogeneric family Ixerbaceae.

However, further testing revealed that Ixerba was closely related to the New Caledonian genus Strasburgeria and it was assigned to the Strasburgeriaceae by the APG III in 2009.

It is said to be widespread from about Kaitaia south to Waitomo, and Te Urewera, including the Tutamoe Ranges, the Waitākere Ranges, Waipoua Forest, Te Moehau on the Coromandel Peninsula, higher elevations on the Barrier Islands and elsewhere around the Bay of Plenty.

Tawari can often be found together with the New Zealand kauri Agathis australis in the understory of the lowland rain forest.

The species has a preference for shaded or sheltered locations, often in permanently damp soil and near streams.

Tawari has a mass flowering strategy, attracting a range of visitors with the abundant nectar it produces.

Seeds are primarily dispersed by birds, with reports including kererū, pōpokotea, hihi, and kākā.