silkoak USDA PLANTS Symbol: GRRO
U.S. Nativity: Exotic
Habit: Hardwood Trees
Grevillea robusta A. Cunningham ex R. Br.

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Taxonomic Rank: Magnoliopsida: Proteales: Proteaceae
Synonym(s): silky oak, silver oak
Native Range: Queensland, New So. Wales (BAIL);

Appearance
Grevillea robusta is a perennial tree that can grow up to 65.6-98.4 ft. (20-30 m) tall.
Foliage
Bark is dark grey with a lace-like pattern. The foliage of this plant is very fern-like. Leaves are pinnate to bipinnate, 3.9-13.4 in. (10-34 cm) long with a green upper surface and a silvery lower surface.
Flowers
Flowers are bright orange, 0.78 in. (2 cm) long, in pairs along flower spikes, and grouped into compound recemose inflorences that are then grouped into panicles of 1 to 6.
Fruit
Fruits are two-seeded, slender and 0.78 in. (2 cm) long. Seeds are 0.51-0.75 in. (13-19 mm) long, winged with a brown, ovate central seed body.
Ecological Threat
Grevillea robusta prefers disturbed areas including disturbed rainforests and along riverbanks. It is native to Australia.

Selected Images from Invasive.orgView All Images at Invasive.org


Seedling(s);
Forest and Kim Starr, Starr Environmental, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Dennis Haugen, , Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Lesley Ingram, , Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Lesley Ingram, , Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Dennis Haugen, , Bugwood.org
Additional Resolutions & Image Usage

Foliage; Leaves, dyed green.
Lyndon Photography, , Bugwood.org
Additional Resolutions & Image Usage

Foliage; Leaves, close-up.
Lyndon Photography, , Bugwood.org
Additional Resolutions & Image Usage

Foliage; Leaves, dyed green.
Lebermuth Company, , Bugwood.org
Additional Resolutions & Image Usage

EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org
 


State(s) Where Reported invasive.
Based on state level agency and organization lists of invasive plants from WeedUS database.

U.S. National Parks where reported invasive:
Haleakala National Park (Hawaii)



Invasive Listing Sources:
Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
Reichard, Sarah. 1994.  Assessing the potential of invasiveness in woody plants introduced in North America. University of Washington Ph.D. dissertation.
University of Hawaii, Botany Department, Hawaiian Alien Plant Studies, 1998