Belongs within: Grevilleoideae.
Grevillea is a genus of over 350 species of trees and shrubs found in Australia and New Guinea. Outlying species are also found on Sulawesia and New Caledonia. Of the three species found in New Guinea, G. baileyana and G. glauca are shared with northern Australia whereas G. papuana is endemic to New Guinea (Foreman 1995). Members of the genus are characterised by the production of fruits as leathery follicles with seeds often winged all around.
Some species of Grevillea are popular garden plants for their bright comb-like flowers. One such species is the largest member of the genus, the silky oak G. robusta, a native of coastal eastern Australia growing to over 30 m in height. The sand grevillea G. arenaria is a spreading shrub with leaves that are more or less hairy on the lower surface, found in western New South Wales.
The creeping grevillea
Published 29 October 2024
Grevillea is certainly one of the most celebrated genera of plants in Australia. Not only have over 360 species been recognised to date, making it one of the continent’s most diverse genera, but many of those species are widely cultivated for their bright, architectural flowers. Perhaps the most famous of these is the silky oak Grevillea robusta but the genus also includes many species that sit on the other end of the habitus spectrum from that tall tree. Among these is the creeping grevillea Grevillea repens.
As indicated by both its vernacular and botanical names, Grevillea repens is a prostrate shrub, growing in mats up to about three metres in diameter. It bears narrow leaves up to 11.5 cm long and four centimetres wide, with between five and nineteen (rarely up to 25) primary teeth or lobes spaced evenly around the leaf’s margin. These teeth sometimes end in a spine, demonstrating G. repens’ membership of a group known as the ‘holly-leaved grevilleas’. Flowers are borne in erect to decurved clusters along one side of a rachis up to eight centimetres long (Makinson 2000). Seeds possess an elaiosome (a fatty body at one end) and, like other seeds with this structure, are probably dispersed by ants.
In the wild, Grevillea repens is a rare and localised species, found in a small number of locations northwest and northeast of Melbourne. It is restricted to dry, montane forests with its range divided by lowlands. As a result of this division, the western and eastern populations are somewhat divergent in appearance. The western ‘Daylesford form’ tends to have more wedge-shaped leaf bases, longer floral bracts, and bears yellow-green to red flowers. The eastern ‘Mount Slide form’ tends to have more truncate leaf bases, shorter floral bracts, and bears red to maroon flowers (Makinson 2000; Holmes et al. 2009). Plants of the western population are able to regenerate after flowers from dormant buds in lignotubers, whereas those in the eastern population may spread via shoots from root-suckers (Holmes et al. 2009).
Genetic surveying of Grevillea repens populations by Holmes et al. (2009) confirmed that this population divergence pre-dates European settlement, and is presumably the result of the species’ range contracting as the climate grew warmer. However, genetic variation within populations was surprisingly low, whether due to population bottlenecks or a preponderance of vegetative propagation over seed growth. The eastern population in particular showed evidence of clonality with over ten percent of individuals tested proving to have triploid rather than diploid genomes. Whether these triploid individuals were capable of setting seed, or whether they multiplied purely by suckers, remained an open question.
As a result of its localised, divergent populations and low genetic diversity, Grevillea repens is considered vulnerable to environmental threats. Holmes et al. (2009) recommended that the eastern and western populations be managed as distinct units for the purposes of conservation. Perhaps hope for G. repens lies in its appeal as a garden plant, producing a handsome ground-cover for the enthusiastic horticulturalist.
Systematics of Grevillea
Characters (Foreman 1995): Leaves spiralled to alternate, simple or pinnate, usually with differentiated upper and lower surfaces. Inflorescences terminal or axillary, panicles or raceme-like, sometimes with flowers borne on one side. Peduncles absent. Indumentum adpressed, hairs 2-branched or appearing to be attached near the middle. Flowers bisexual, pedicellate, in pairs, subtended by small, non-persisting bract; floral bracts absent. Perianth mostly recurved; limb oblique, globular, segments coherent at limb for some time after tube splits open. Anthers all perfect, ovate or oblong, sessile in concave limb segments; connective not usually prolonged. Disc fleshy, semi-annular or annular, mostly entire or sometimes more or less bilobed. Ovary shortly stipitate or sessile, 1-locular; ovules 2, hemitropous, attached laterally; style often elongated, protruding from slit on lower side of tube, retained for some time by coherent limb segments, eventually free; pollen presenter more or less dilated, straight, oblique or lateral and disc-like; stigma usually in centre of pollen presenter. Fruit a follicle, coriaceous to woody. Seeds 1 or 2, flat, orbicular or oblong, winged all around or occasionally wingless.
Grevillea
|--G. acuariaG04b
|--G. adenotrichaLK14
|--G. agrifoliaLK14
| |--G. a. ssp. agrifoliaLK14
| `--G. a. ssp. microcarpaLK14
|--G. alpinaMB97
|--G. anethifoliaG04b
|--G. arenariaT08
| |--G. a. var. arenariaT08
| `--G. a. var. canescensT08
|--G. aspleniifoliaH90
|--G. baileyana McGillivray 1993 (see below for synonymy)F95
|--G. banksiiA91
|--G. bipinnatifidaS35
|--G. bracteosaB00
|--G. browniiGK00
|--G. cagianaG04b
|--G. calcicolaK90
|--G. caleyiH90
|--G. candelabroidesK90
|--G. chrysodendronC16
|--G. cirsiifoliaM87
|--G. craveniiLK14
|--G. cunninghamiiLK14
|--G. decipiensG04b
|--G. depauperataGK00
|--G. dimidiataLK14
|--G. diversifoliaGK00
|--G. donaldianaLK14
|--G. dryandriLK14
|--G. erectilobaG04a
|--G. eriostachyaM93
|--G. eryngioidesH18
|--G. erythrocladaLK14
|--G. fasciculataGK00
|--G. georgeanaG04a
|--G. glauca Knight 1809 [incl. G. gibbosa Brown 1810]F95
|--G. goodiiM87
|--G. heliospermaLK14
|--G. helmsianaH15
|--G. huegeliiB00
|--G. ilicifoliaR35
|--G. insignisG04b
| |--G. i. ssp. insignisG04b
| `--G. i. ssp. elliotiiG04b
|--G. integrifoliaS95
|--G. juncifoliaMLP09
|--G. juniperinaB00
|--G. lanigeraG76
|--G. latifoliaLK14
|--G. laurifoliaM87
|--G. lavandulaceaB00
|--G. leptobotrysGK00
|--G. linearisC08
|--G. longifoliaH90
|--G. longistylaB96
|--G. lullfitziiG04b
|--G. maheraeLK14
|--G. microstylaLK14
|--G. mimosoidesLK14
|--G. miquelianaM89
|--G. monticolaLK00
|--G. mucronulataB96
|--G. myosodesLK14
|--G. nematophyllaG04b
|--G. obliquistigmaG04a
|--G. paniculataS95
|--G. papuana Diels 1916 [incl. G. subargentea White 1922]F95
|--G. paradoxaG04a
|--G. parallelaLK14
|--G. petrophiloidesS95
|--G. pilosaG04b
|--G. piluliferaGK00
|--G. polystachyaC16
|--G. prasinaLK14
|--G. pritzeliiS95
|--G. pteridifoliaB00
|--G. pterospermaCC03
|--G. pulchellaGK00
|--G. puniceaNC91
|--G. pyramidalisLK14
| |--G. p. ssp. pyramidalisLK14
| `--G. p. ssp. leucadendronLK14
|--G. quercifoliaGK00
|--G. ramosissimaB96
|--G. refractaLK14
|--G. renwickiana von Mueller 1887M87
|--G. repensM87
|--G. robustaSK02
|--G. rogersonianaK90
|--G. sarissaCC03
|--G. scabraLK00
|--G. sericeaH87
|--G. stenobotryaB05
|--G. stenomeraK90
|--G. stenophyllaK90
|--G. striataC16
|--G. thelemanianaK90
| |--G. t. ssp. thelemanianaK90
| `--G. t. ssp. pinasterK90
|--G. trinervisC08
|--G. triternataB96
|--G. variifoliaK90
|--G. wickhamiiLK14
| |--G. w. ssp. wickhamiiLK14
| `--G. w. ssp. pallidaLK14
`--G. wilsoniiGL04
Grevillea baileyana McGillivray 1993 [incl. G. edelfeltii Muell. 1885 (n. n.), Kermadecia pinnatifida Bailey 1886, G. pinnatifida (Bailey) Bailey 1886 non Jacques 1843]F95
*Type species of generic name indicated
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