|Scientific Name:||Mellissia begonifolia (Roxb.) Hook.f.|
Mellissia begoniifolia (Roxb.) Hook.f. [orth. error]
Physalis begonifolia Roxb.
|Red List Category & Criteria:||Critically Endangered B1ab(iii,iv,v)c(i,ii,iii,iv)+2ab(iii,iv,v)c(i,ii,iii,iv); C2a(i,ii)b; D ver 3.1|
|Assessor(s):||Lambdon, P.W. & Ellick, S.|
The world Boxwood (Mellissia begonifolia) population is confined to a single, very restricted locality. Plants are short-lived and the exact total varies substantially, but it does not exceeded 50 mature individuals, or at least it has not done so for a number of years. On occasions the standing crop has disappeared entirely, with survival of the population dependent on regeneration from a seed bank. These factors alone is sufficient to satisfy the requirements for Critically Endangered status under criteria B, C and D.
|Previously published Red List assessments:|
|Range Description:||Boxwood is endemic to the island of St Helena, South Atlantic Ocean, where it survives at a single locality on the steep, dry slopes bordering the south coast.|
The extent of occurrence (EOO), based on the area of a minimum convex polygon around known localities, is 113 m2. The area of occupancy (AOO), based on a 2 km × 2 km grid, is 4 km2. Following IUCN Red List Guidelines, the EOO is therefore increased to 4 km2 to match the AOO.
The much depleted population persists only in a single, very restricted patch on a boulder field below Lot’s Wife, where a dense cluster of several shrubby plants emerge in most years, crowded into an area no more than 6 m across.
The original native range of this species remains poorly known. It was already rare by the early 19th Century when the first detailed notes on St Helena’s flora were made. Burchell (1805-10) recorded it from Long Range and Little Stone Top (where one adjacent low summit still bears the name of ‘Boxwood Hill’). Melliss (1875) only specifically noted it from Long Range but also added “… and the south-eastern parts of the coast”.
Native:Saint Helena, Ascension and Tristan da Cunha (Saint Helena (main island))
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||Following the botanical works of the 19th Century, no further records were made for some time and the species was thought to be extinct by the late 20th Century. In 1998, the current patch was rediscovered by local conservationist Stedson Stroud. Despite the tiny extent of the population, it has persisted here for at least 17 years. This is all the more remarkable in view of the extreme fluctuations in population size. When rediscovered there were only 1 living and 6 dead plants present. In 2001 there were 6 and by 2003 numbers had risen to 16. In 2007-2008, efforts were made to water the plants during the dry summer months and numbers appear to have peaked at this time, with 33 in 2008 and 35 in 2009. However, by 2010, no mature individuals survived. In 2012 there were eight, but these also died. In 2013 several large immature plants reappeared, but none had matured by the summer and only 1-3 of them survived to flower in 2014.|
|Current Population Trend:||Decreasing|
|Habitat and Ecology:|
The ecology of Boxwood remains something of a mystery as the current population can barely be said to be flourishing in a healthy, functioning state. At Lot’s Wife it grows on moderately rich soil accumulated in pockets between boulders. Situated at low altitude, the location receives little rainfall, with the few significant showers mainly confined to the winter months. This habitat may well be moderately representative of that formerly occupied. From what is known of the original range, there appeared to be a preference for dry, rocky places on the south-facing coastal hills at altitudes of 200 – 450 m.
|Continuing decline in area, extent and/or quality of habitat:||Yes|
|Movement patterns:||Not a Migrant|
Boxwood is threatened with imminent extinction in the wild, and faces a number of problems. The first of this arises from the very small extent of the world population, which leaves the only colony very vulnerable to chance catastrophes. It is possible that seed could occasionally be taken and distributed by non-native finches or Mynas (Acridotheres tristis L.), but there appear to be few natural dispersal mechanisms and the chances of spread are low. Attempts to seed individuals more widely on the boulder field have been unsuccessful.
Ultimately, the decline of the Boxwood may have been largely a result of an inability to cope with introduced pests, competitors and diseases, against which most of the arriving non-native flora has some resilience. However, the loss of vigour which appears to have occurred since the 1800s seems extreme, and is difficult to explain. It may be a result of inbreeding amongst the tiny population, greatly reducing the gene pool and causing associated health problems. Melliss noted that the leaves had a strong scent, whereas modern plants often have little. This may indicate a declining ability to produce the toxic alkaloids which confer protection against many herbivores. It is therefore not necessarily the case that Boxwood is intrinsically a ‘weak species’, and could have fared better had it survived to the modern era of conservation in greater numbers.
St Helena is in the process of developing a National Protected Areas Network, and the wild Boxwood population is due to fall within the Sandy Bay National Park. It will thus be protected under the National Conservation Area development plans. The species will also be protected under the new Environmental Protection Ordinance, in the final stages of drafting and expected to be issued in 2016.
Burchell, W.J. 1805-10. Flora Insulae Sanctae Helenae. Unpublished manuscript held at Royal Botanic Gardens Kew, Richmond, U.K.
Cairns-Wicks, R. 2003. Mellissia begonifolia. The IUCN Red List of Threatened Species 2003: e.T44011A10848988. doi: /10.2305/IUCN.UK.2003.RLTS.T44011A10848988.en.
Cairns-Wicks, R. Draft Recovery Action Plan for Mellissia begonifolia (Solanaceae).
Cronk, Q.C.B. 2000. The Endemic Flora of St. Helena. Anthony Nelson Publishers, Oswestry, UK.
Fay, M.,Thomas, V.E. and Knapp, S. 2007. ellissia begoniifolia. Curtis’s Botanical Magazine 24: 243–250.
IUCN. 2016. The IUCN Red List of Threatened Species. Version 2016-1. Available at: www.iucnredlist.org. (Accessed: 30 June 2016).
Lambdon, P. 2012. Flowering Plants and Ferns of St Helena. Pisces Publications, Newbury, UK.
Melliss, J.C. 1875. St Helena: A physical, historical and topographical description of the Island including its geology, fauna, flora and meteorology. Reeve, London.
Royal Botanic Gardens, Kew. 2009. Data extracted from notes accompanying collection of herbarium specimens. Accessed 2009. Royal Botanic Gardens, Kew, London.
|Citation:||Lambdon, P.W. & Ellick, S. 2016. Mellissia begonifolia. The IUCN Red List of Threatened Species 2016: e.T44011A67372413.Downloaded on 24 November 2017.|
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