Eucalyptus angustissima, or narrow-leaved mallee, is a small tree that is native to the south of Western Australia.

The bark is smooth or matt, mottled grey and very white/grey or light grey-brown.

The buds occur in clusters of up to 7 and are followed by creamy-white flowers that appear between August and January[2] and hemispherical fruits 0.5 to 0.8 cm wide.

quaerenda was described in the journal Telopea in 1992 by L.A.S.Johnson and K.D.Hill from samples collected by Johnson and Maxwell from near Lake Chinocup.

It will grow in white or grey sands, clay, loam, sometimes saline soils in scrubland or woodland areas.