Hymenachne amplexicaulis explained

Hymenachne amplexicaulis, also known as West Indian marsh grass in the US, Olive hymenachne in Australia, and hereafter referred to as hymenachne, is New World species[1] in the genus Hymenachne. Hymenachne is from the Greek hymen meaning "membrane" and achne meaning "chaff, glume, scale" and amplexicaulis is from Latin, literally "embracing the stem" or "stem-clasping.[2] [3] This freshwater species is native to the tropical and subtropical regions of the West Indies, Northern South America, and Central America.

Biology

Hymenachne is a perennial grass that primarily reproduces via stolons.[4] This robust species is commonly found growing 1–2.5m tall. The stems are hairless and float prostrate across the top of the water, then grow upright from these bases to support leaves. The flat, triangular leaves (10–45 cm long, up to 3 cm wide) have a prominent clasping bases, or auricles. The auricles help to distinguish it from other invasive wetland grasses and the native H. acutigluma in Australia.[5] Hymenachne has been shown to increase the stem length between nodes to keep leaves above water during periods of flooding.[6] Its stem is packed with airy tissue called aerenchyma to help the stems float and to aid in flood tolerability.

Hymenachne flowers in the early fall and seeds in late fall.[7] The flower is a panicle[8] that can grow to half a meter. Researchers at the University of Florida have seen multiple panicles per plant originating from branching at a single node.[9] Hymenachne can produce thousands of seeds with up to 98% germination right off the panicle.[10]

Habitat

Hymenachne prefers constantly inundated soil and is known to survive comfortably in about a meter of water for 20 years. This species was shown to survive poorly in Australia where flooding exceeded 1.2 m.[11] [12] In its native range in Venezuela, and in invaded areas of Florida, hymenachne was documented to survive in >1.2m of water for nearly a year.[13] [14] Hymenachne has also been found in water greater than 4m deep persisting in floating mats, likely dislodged after a storm event. Conversely, hymenachne is not recorded to survive sites that entirely desiccate.[15]

Hymenachne is known to colonize and form dense monocultures in floodplains, roadside ditches, and lake margins in invaded and native areas.[16] [17] It is often found colonizing areas with little shading and competition from other species. Although limited information is available on soil preferences of hymenachne, it has been found in deep, poorly drained muck soils in Florida.[18] It is not found in waters with a significant salt concentration.[19]

Invasion

There have been three introductions of hymenachne into Australia, one in Florida, and one in Louisiana.[20] [21] Australia now lists hymenachne as one of the top twenty worst weeds.[22] Hymenachne invasions have been shown to decrease species richness, increase invasive fish populations, and overall cause fundamental changes in floral and faunal composition in Australia.[23] Hymenachne was introduced in Australia as forage for cattle, and likely for the same reason in Florida. The species was used in ponded pastures, or artificial ponds created to hold water for use in the dry season. High reproducibility from stem fragments aids in the dispersal and invasion of this species.[24] The first herbarium record of hymenachne in Florida is from 1957.[25] The second specimen is not recorded until 1977. The cause for this gap is unknown; however, today it is recorded in 28 counties across the state.[26] [27]

Notes and References

  1. Web site: Hymenachne amplexicaulis (hymenachne). www.cabi.org. en. 2019-02-17.
  2. Book: Quattrocchi, Umberto. CRC World Dictionary of Grasses: Common Names, Scientific Names, Eponyms, Synonyms, and Etymology - 3 Volume Set. 2006-04-26. CRC Press. 9781420003222. en.
  3. Web site: Indiana Dunes Plant Guide - Asclepias amplexicaulis. indianadunesguide. en. 2019-04-02.
  4. Csurhes, S.M., Mackay, A.P. and Fitzsimmons, L. (1999). Hymenachne (Hymenachne amplexicaulis) in Queensland (Department of Natural Resources, Brisbane, Australia).
  5. Wearne. Lynise J.. Clarkson. John. Grice. Anthony C.. van Klinken. Rieks D.. Vitelli. Joseph S.. 2010. The Biology of Australian Weeds 56. 'Hymenachne amplexicaulis' (Rudge) Nees. Plant Protection Quarterly. EN. 25. 4. 146.
  6. Kibbler. H.. Bahnisch. L.M.. 1999. Physiological adaptations of Hymenachne amplexicaulis to flooding. Australian Journal of Experimental Agriculture. en. 39. 4. 429–435. 10.1071/ea98127. 1446-5574.
  7. Diaz, R., Overholt, W.A., Cuda, J.P., Pratt, P.D. and Fox, A. (2009). Host specificity of Ishnodemus variegates, an herbivore of West Indian marsh grass (Hymenachne amplexicaulis). BioControl 54, 307-21.
  8. Campbell, S.D., Carter, E.A. and Setter, M.J. (2009). Germination of Hymenachne amplexicaulis and H. acutigluma under contrasting light, temperature and nitrate regimes. Plant Protection Quarterly 24, 10-14.
  9. K. Quincy unpublished data
  10. Tropical Weeds Research Centre. 2006. Hymenachne (Hymenachne amplexicaulis) control and management in Queensland. http://www.nrm.qld.gov.au/ tropical_weeds/projects/hymenachnecontrol.html. Accessed February 17, 2019.
  11. Gonzalez-Jimenez, E. and Escobar, A. (1977). Flood adaptation and productivity of savanna grasses. Proceedings of Plant Protection Quarterly Vol.00(0) 0000 15 the 13th International Grassland Congress Sec. Pap. Sections 3-4-5, Leipzig.
  12. Lyons, J. (1991). Developing ponded pastures at ‘Wambiana’. Ponded pastures in North Queensland, eds P. Anning and J. Kernot. North Queensland Beef Production Series. Department of Primary Industries, Queensland Government.
  13. Tejos, M.R. (1980). Production of water straw grass (Hymenachne amplexicaulis (Rudge) Nees) during a savanna period. Congreso Venezolano de Zootecnia, Guanare (Venezuela), p. 54.
  14. Kalmbacher, R., Mullahey, J. and Hill, J. (1998). Limpgrass and hymenachne grown on flatwoods range pond margins. Journal of Range Management 51, 282-7.
  15. Medina, E. and Motta, N. (1990). Metabolism and distribution of grasses in tropical flooded savannas in Venezuela. Journal of Tropical Ecology 6, 77-89.
  16. Costa, M. (2005). Estimate of net primary productivity of aquatic vegetation of the Amazon floodplain using Radarsat and JERS-1. International Journal of Remote Sensing 26, 4527-36.
  17. Enriquez-Quiroz, J.F., Quero-Carrillo,A.R., Hernandez-Garay, A. and Garcia-Moya, E. (2006). Azuche, Hymenachne amplexicaulis (Rudge) Nees, forage genetic resources for floodplains in tropical Mexico. Genetic Resources and Crop Evolution 53, 1405-12.
  18. Hill, K.U. (1996). Hymenachne amplexicaulis:A review of the literature andsummary of the work in Florida. URL: http://www.naples.net/~kuh/hymen.htm (accessed 17 Feb 2019).
  19. Meerman, J.C., Howe, A., Choco, S., Ack, A., Choc, E., Kok, S. and Muke, A. (2006). Rapid ecological assessment of aguacalient wildlife sanctuary. Aguacaliente REA. Data stored in BERDS: URL: http://www.biodiversity.bz (accessed 17 Feb 2019).
  20. Urbatsch LE; Saichuk JK, 2014. Hymenachne amplexicaulis new for Louisiana. Phytoneuron, 50:1-4.
  21. Web site: Hymenachne Amplexicaulis. August 2018. Florida Natural Areas Inventory. 17 Feb 2019.
  22. Williams. Jann A.. West. Carol J.. 2000. Environmental weeds in Australia and New Zealand: issues and approaches to management. Austral Ecology. en. 25. 5. 425–444. 10.1046/j.1442-9993.2000.01081.x. 1442-9993.
  23. Duivenvoorden. Leo J.. Houston. Wayne A.. 2002. Replacement of littoral native vegetation with the ponded pasture grass Hymenachne amplexicaulis: effects on plant, macroinvertebrate and fish biodiversity of backwaters in the Fitzroy River, Central Queensland, Australia. Marine and Freshwater Research. en. 53. 8. 1235–1244. 10.1071/mf01042. 1448-6059.
  24. Sellers, B.A., Diaz, R., Overholt, W.A., Langeland, K.A. and Gray, C.J. (2008). Control of West Indian marsh grass with glyphosate and imazapyr. Journal of Aquatic Plant Management 46, 189-92.
  25. Web site: University of Florida Herbarium (FLAS) Collection Catalog. www.floridamuseum.ufl.edu. 2019-02-17.
  26. Book: Guide to the vascular plants of Florida. Wunderlin, Richard P.. 2011. University Press of Florida. Hansen, Bruce F.. 9780813035437. 3rd. Gainesville, FL. 700199921.
  27. Web site: West Indian marsh grass (Hymenachne amplexicaulis) - EDDMapS State Distribution. EDDMapS.org. en. 2019-02-17.

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