Grevillea longifolia is a narrow-range endemic with a distribution restricted to New South Wales in Australia. Within New South Wales, Grevillea longifolia is primarily found in the southern half of the Sydney Basin and the Woronora Plateau. It grows in moist forests on yellow clay soils and Sydney Basin Hawkesbury Sandstone, typically along the banks of rivers, streams, gullies, and creeks.
Formerly considered a variety of Grevillea aspleniifolia, the species has kept the associated common names of fern-leaf spider flower and fern-leaf grevillea (Asplenium being a genus of ferns). Fern-leaf grevilleas have “toothbrush” inflorescences, resembling a one-sided toothbrush. The group of related species that make up toothbrush grevilleas occur in many parts of Australia. In Grevillea longifolia, these racemes bear flowers that are deep red to pink in colour. Flowers can start to bloom in late winter and continue through to early summer, after which they are followed by densely hairy fruits. Grevillea longifolia is a shrubby species that can rapidly grow to a height of 3m and spread of 5m. (10-16ft.). Fern-leaf spider flower produces plentiful rich nectar (an attractant to many bird species), while the seeds also provide food for wildlife.