Austrostipa ramosissima

Stout Bamboo Grass

Austrostipa ramosissima (Trin.) S.W.L.Jacobs & J.Everett

Austrostipa ramosissima is an attractive tufted perennial grass with a short rhizome easily recognised by its culms (stems) with whorled branches giving it a bamboo - like appearance and the common name Stout Bamboo Grass. Growing 1 to 2.5 m tall it produces attractive large fine textured inflorescences throughout the year. The open spreading panicle is 8 to 50 cm long with striking long, bent awns on the seeds. It flowers for long periods, often year round, adding to its attractiveness as a landscape plant.

Austrostipa ramosissima grows in moist, well-drained gullies, near forest or woodland margins. It occurs predominately from south eastern Queensland to far south eastern New South Wales, with isolated occurrences in north eastern Queensland and central New South Wales.

Propagation by division in late winter - early spring has high success rates. Seed can prove a little more difficult. Many Austrostipa species have an after-ripening dormancy, and seed may need to be stored for a particular time period, usually between 2–24 months prior to sowing. The amount of time varies among species. Smoke treatments have been found to improve germination in some species. Seed should be sown in autumn to plant out in late winter or early spring. Germination occurs in 3 to 10 weeks for non-dormant seed. As with many other species of Australian plants more research is needed to understand dormancy and germination mechanisms.

Native grasses are great additions to gardens as they encourage seed eating birds, provide refuge for small reptiles, require little maintenance and help exclude weeds. This attractive grass, with its large feathery inflorescences creates striking displays in gardens and large scale landscapes. Mass planting increases this impact and Austrostipa ramosissima can also be used as an interesting border plant or to soften hard edges. They can be detailed to show off the bamboo-like canes, and display well when planted up against rocks or walls.

Whilst this is a hardy species Austrostipa ramosissima does best in damp sites or in heavy soils. When grown in exposed dry sites plants respond well to additional watering throughout summer. It also grows well in a sheltered position and provides contrast in the understory. The application of a native plant fertiliser is recommended in early spring. Being a cool season C3 grass, its main growth period is in winter and spring. Mature plants can be cut back hard to just aboveground level in late winter to reinvigorate and encourage new growth. It is a relatively low maintenance species but some selective weeding may be necessary as there is potential for seedlings to spread throughout the garden.

Julie Percival, Volunteer Botanical Training Program Participant 2016

References:

Dawson, I. & Winder, S. (1999) Native Grass Restoration in the Australian Capital Territory Water Catchment: Maximising Seed Germination. Australian National Botanic Gardens. Available at https://www.anbg.gov.au/gardens/research/hort.research/grass-project/index.html [Accessed 12th February 2016].

Everett, J., Jacobs, S.W.L. & Nairn, L. (2009) Austrostipa, Flora of Australia Volume 44A Poaceae 2. Melbourne: ABRS/CSIRO Australia.

Howe, A. (2016) Horticulturist, Australian National Botanic Gardens. Technical advice and assistance.

Jacobs, S.W.L & Everett, J. (1996) Austrostipa, a new genus, and new names for Australasian species formerly included in Stipa (Gramineae). Telopea 6(4): 579-585.

Nightingale, M. (2016) Herbarium Registrar, Australian National Herbarium. Technical advice and assistance.

Ralph, M. (2003) Growing Australian Native Plants from Seed for revegetation tree planting and direct seeding. Murray Ralph/Bushland Horticulture.

Watson, L. & Dallwitz, M.J. (1992 onwards) The grass genera of the world: descriptions, illustrations, identification and information retrieval; including synonyms, morphology, anatomy, physiology, phytochemistry, cytology, classification, pathogens world and local distribution and references. Version: 7th December 2015. Available at http://delta-intkey.com [Accessed 6th February 2016].

Williams, A. R. (2011) Austrostipa (Poaceae) subgenus Lobatae in Western Australia. Telopea 13(1-2): 177-192.

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