Caley's Grevillea

Grevillea caleyi is an open, spreading shrub that typically grows 1–4 m (3 ft 3 in – 13 ft 1 in) tall and up to 4 m (13 ft) wide. It has characteristic, deeply divided "herringbone" leaves that are comparatively large in size, 70–180 mm (2.8–7.1 in) long and 30–75 mm (1.2–3.0 in) wide with 19 to 36 linear to lance-shaped lobes, with the narrower end towards the base. The lobes are 15–35 mm (0.59–1.38 in) long, 2–6 mm (0.079–0.236 in) wide with the edges turned downwards, and hairy on the lower surface. The flowers are arranged in toothbrush-like groups on a rachis 40–80 mm (1.6–3.1 in) long. The perianth is fawn with a villous outside. The pistil is 25–28 mm (0.98–1.10 in) long with a maroon-red style and a green pollen presenter at the tip. The pistil is 25–28 mm (0.98–1.10 in) long and the style is glabrous. Flowering is sporadic and occurs throughout the year, mostly from August to December. Fruit is a woolly hairy follicle 17–21 mm (0.67–0.83 in) long with reddish brown stripes or blotches. A single, woody ellipsoidal seed 15–20 mm (0.59–0.79 in) long and 4–5 mm (0.16–0.20 in) wide is contained inside each follicle. It is a distinctive and easily recognisable species, most closely related to G. aspleniifolia.

Caley's grevillea is restricted to an area of 64 km2 (25 sq mi) in the suburbs of Terrey Hills, Belrose and Ingleside, and the endangered ecological community of Duffys Forest. It grows in woodland on iron-rich laterite sandstone soils on ridgetops between elevations of 170 to 240 metres (560 to 790 ft) above sea level in open forest. Species commonly associated with G. caleyi include the trees Corymbia gummifera, Eucalyptus sieberi, Eucalyptus haemastoma, Banksia serrata and Xylomelum pyriforme, the shrubs Acacia myrtifolia, Banksia spinulosa, Conospermum longifolium, Grevillea buxifolia, Hakea dactyloides, Lambertia formosa, Pimelea linifolia and Telopea speciosissima and herbaceous plants including Anisopogon avenaceus, Dampiera stricta, Lomandra glauca, Lomandra obliqua and Pteridium esculentum.

Grevillea caleyi is killed by fire, and since it does not form a lignotuber and does not propagate by suckering, it relies entirely on seed that is stored in the soil for regeneration. Seedlings can grow without bushfires, however, they sprout in large numbers after recent bushfires, suggesting that the seeds may remain dormant in the soil until growth is stimulated, perhaps by intense heat, smoke or exposure to bright sunlight. Due to fecundity being low (only approximately 3% of flowers resulting in seed), seed dispersal being low and seed predation being high, it is estimated that it takes 8–12 years for a sufficient seedbank to develop to be able to replace a population. Generally, seedlings are not able to produce flowers or seeds before 2–5 years of age. This species is pollinated by birds. Through casual observations, the likely common pollinators for this species include honeyeaters such as New Holland, white-eared and white cheeked, silvereyes, Little wattlebirds and Eastern spinebills. It is thought this species may be self-compatible as well.

Caley's grevillea is occasionally grown as an ornamental plant, and has been grown in a variety of gardens across Australia. Like most grevilleas, it grows best in well-drained, acidic, gravelly or sandy loam soil in a sunny position for optimal flowering, though it will also grow in some shade. It tolerates frosts to at least −6 °C (21 °F) and can tolerate extended dry periods, but not drought. It is usually propagated from seed and will self-sow in the garden, but it may also be readily propagated from cuttings or grafted onto rootstock, usually G. robusta, which allows it to grow in a wider variety of soils. Grafted G. caleyi tend to be hardier and live longer than plants grown from seed. It hybridises easily with other related grevillea species, such as with G. aspleniifolia and G. longifolia, which has resulted in a large variety of hybrids and cultivars becoming available, including several 'Poorinda' varieties such as 'Poorinda Empress' and 'Poorinda Emblem'. The cultivar Grevillea 'Ivanhoe' is said to be a hybrid between G. caleyi and G. longifolia.

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