Helonias

Helonias bullata (swamp pink) is a rare perennial rhizomatous herb native to the eastern United States, in the genus Helonias together with Helonias orientalis (Thunb.) N.Tanaka. The root system is extensive in comparison to the apparent size of the plant on the surface. Blooming in March to May, its fragrant flowers are pink and occur in a cluster at the end a vertical spike which may reach up to 3' in height. It has evergreen, lance-shaped, and parallel-veined leaves ranging from dark green to light yellow green in color that form a basal rosette.[1]

Helonias

Vulnerable  (NatureServe)
Scientific classification Edit this classification
Kingdom: Plantae
Clade: Tracheophytes
Clade: Angiosperms
Clade: Monocots
Order: Liliales
Family: Melanthiaceae
Tribe: Heloniadeae
Genus: Helonias
L. 1753 not Adans. 1763
Species:
H. bullata
Binomial name
Helonias bullata

Swamp pink is a federally threatened species that was historically distributed from Staten Island, New York to the southern Appalachians. Currently, New Jersey supports the largest and most numerous populations, but there are populations in six other states: Delaware; Maryland; Virginia; West Virginia;North Carolina; South Carolina, and Georgia.[2][3] There is also some unverified indication that a population of swamp pink has survived on Staten Island. Populations of swamp pink are on occasion subject to poaching by plant enthusiasts and others who prize the early bright pink blooms.[4] Unfortunately, the poached plants likely do not survive their move owing to the high sensitivity to being removed from the water saturated environment, underestimation of the size of the root mass, and failure to replicate the necessary environment sufficiently.[5]

United States Fish and Wildlife Service has instituted a volunteer monitoring project, “Adopt-a-Swamp-Pink Population”. The program has been further expanded by a joint volunteer effort with Citizens United to Protect the Maurice River and Its Tributaries, Inc. The survey results are shared with U.S.F.W.S. and the New Jersey Natural Heritage database.[6][7]

Habitats

Swamp pink occurs in wetland habitats and it requires habitat which is saturated, but not flooded, with water. Ideally the plant prefers an environment where the water table sits at about the level of the top of its root system, but not covering the basal rosette. Typical areas include swampy forested wetlands which border small streams; meadows, and spring seepage areas. It is often found near conifer trees.[1]

Variation in genetic diversity

Low genetic diversity

Many extant populations suffer low genetic diversity.[8] This could be explained as a result of high self-fertilization rate due to harsh environmental conditions that affect successful cross-fertilization, such as limited seed dispersal range and browsing from predators.[8]

Mechanisms of seed dispersal

Helonias seeds have a lipid structure that allows seed dispersal through water.[9] This is a result of natural selection considering the ‘watery’ habitat (i.e. swamp and wetland) of Helonias, and it accounts for the long-distance seed dispersal.[9] It is also known that ants actively engage in Helonias seed dispersal.[9]

Limitations in seed dispersal

Although ants can help facilitate the dispersal process, the soil in such watery environment is saturated and makes it difficult for ants to co-habitate with Helonias, lowering the rate of short-distance seed dispersal.[9] The low rate of seed dispersal is also due to limited wind.[9] The seeds are light enough to be dispersed by wind, but low levels of wind prevent the seeds from dispersing further away, resulting in a clustered population of Helonias.[9]

Risks of self-fertilization

Low dispersal increases the risk of self-fertilization.[8] In an evolutionary perspective, this is highly disadvantageous when there is a sudden change in the environment.[10] Since genetic diversity is low, if a predominant trait among the population is selected against, the whole population faces the risk of being wiped out.[10] In the long run, seeds that lure more animals will be favored by selection as opposed to seeds that are lighter, because the seeds dispersed by the animals will be spread over a larger range compared to that of lighter seeds, resulting in a lower risk of self-fertilization.

Illegal poaching

The brilliant pink color of the Helonias flowers attracts poachers. Helonias is a perennial and endures the winter, making it more visible to the poachers. This is one of the reasons why Helonias is considered a threatened species.[11]

References
  1. Flora of North America Helonias bullata
  2. "World Checklist of Selected Plant Families: Royal Botanic Gardens, Kew". kew.org. Retrieved 24 September 2015.
  3. Biota of North America Program 2013 county distribution map
  4. Godt, Mary Jo W.; J. L. Hamrick; Susan Bratton (1995). "Genetic Diversity in a Threatened Wetland Species, Helonias bullata (Lilliaceae)". Conservation Biology. 9 (3): 596–604. doi:10.1046/j.1523-1739.1995.09030596.x.
  5. "Endangered and Threatened Species of the Southeastern United States". Archived from the original on 2007-08-23. Retrieved 2008-02-09.
  6. Pink, A. (2004). Gardening for the Million. Project Gutenberg Literary Archive Foundation. ISBN 978-1-4264-5707-4.
  7. U.S. Fish Wildlife Service Adopt a swamp pink program Archived 2006-09-26 at the Wayback Machine
  8. Sutter, Robert (March 1984). "The Status of Helonias bullata L. (Liliaceae) in the Southern Appalachians". Castanea. 49 (1): 9–16. JSTOR 4033055.
  9. Godt, Mary (June 1995). "Genetic Diversity in a Threatened Wetland Species, Helonias bullata (Liliaceae)". Conservation Biology. 9 (3): 596–604. doi:10.1046/j.1523-1739.1995.09030596.x. JSTOR 2386613.
  10. Lande, Russell (March 2009). "Adaptation to an extraordinary environment by evolutionof phenotypic plasticity and genetic assimilation". Journal of Evolutionary Biology. 22 (1): 1435–1446. doi:10.1111/j.1420-9101.2009.01754.x. PMID 19467134.
  11. Laidig, Kim (June 2009). "Hydrologic Regimes Associated with Helonias bullata L. (swamp pink) and the Potential Impact of Simulated Water-Level Reductions". The Journal of the Torrey Botanical Society. 136 (2): 221–232. doi:10.3159/08-RA-084.1. JSTOR 27751795. S2CID 86010832.
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