It is found in dry vine thickets usually on soils derived from limestone. The leaves are about 3cm x 1cm and borne in opposite pairs. Flowers occur in spring and early summer and are deep red, tubular, about 3cm long and borne singly or in pairs in the leaf axils. In a good flowering season, flowers are borne in almost every axil and the plant becomes a mass of brilliant scarlet red. Seed capsules are club shaped, dry and woody and contain 2 seeds.
Plants also sucker readily and new clumps appear regularly beside established plants.
As pruning is tolerated well, it is easy to establish a hedge or windbreak when suckers emerge. G.excelsum has proven to be reliable in a range of climates from tropical to cool temperate. Best flowering is achieved in full sun or only light scattered shade and nectar feeding birds find the flowers irresistible. Propagation is easy from cuttings or by transplanting suckers. Seed also germinates well from fresh seed.