Dictyosperma album is a palm native to the Mascarene islands. There are three varieties: var. album, var. aureum, and var. conjugatum. The species is categorized as Critically Endangered under C2a(i) because the total population is 169 individuals, with less than 50 individuals in each known wild subpopulation (24 individuals for D. album var. album in Mauritius, the largest subpopulation being seven for D. album var. album in La Réunion, one individual for D. album var. aureum in Rodrigues, one individual for D. album var. conjugatum on Round Island). The population has declined with threats including invasive flora and fauna, climate change, and illegal harvesting.

This palm is native to the Mascarene islands, with each island having its own variety population. Mauritius has a native mainland subpopulation of Dictyosperma album var. album and a population of Dictyosperma album var. conjugatum that is confirmed only from Round Island, to which it may be endemic, located 20 km northeast of mainland Mauritius. Rodrigues, a semi-autonomous island of the Republic of Mauritius, has an endemic population of Dictyosperma album var. aureum. Additionally, La Réunion, has its own native subpopulation of Dictyosperma album var. album.

Palm heart plantations of Dictyosperma album var. album are common to both mainland Mauritius and La Réunion, though these cultivated subpopulations are not included in the assessment as they are not wild palms with self-regenerating subpopulations. Early conservation actions led to the varieties being moved to localities outside their typical range where they are unlikely to naturally occur, leading to the risk of hybridization between the varieties. Recent re-introductions, particularly for D. album var. conjugatum and D. album var. aureum, are not included in this assessment as they are not naturally producing viable progeny yet.

The area of occupancy for the species is calculated at 336 km² and the extent of occurrence was calculated at 59,566 km², using the Geospatial Conservation Assessment Tool (GeoCAT). This is based on there being 100 known wild locations of the species, where there are only a few or one individual at each location, and these locations being found hundreds of kilometres apart within the Mascarenes.

The species is categorized as Critically Endangered under C2a(i) as the population is 169 individuals with less than 50 individuals in each known wild subpopulation (24 individuals for D. album var. album in Mauritius, the largest subpopulation being seven for D. album var. album in La Réunion, one individual for D. album var. aureum in Rodrigues, one individual for D. album var. conjugatum on Round Island).

In total, the population of Dictyosperma album is 169 individuals. There is only one known wild individual of both D. album var. conjugatum and D. album var. aureum. For D. album var. album, Mauritius has a known population of 24 and La Réunion has a known population of 143. This does not include any planted individuals from conservation efforts as they are not yet naturally producing viable offspring or those cultivated in plantations for the palm heart trade or for ornamental use. Each island has conservation efforts underway to propagate these varieties, though hybridization with the more widespread variety D. album var. album, may affect these efforts.

Historic explorer accounts for each of the islands have given a limited baseline for spread and abundance of each of the varieties across the Mascarenes. Generally, this species was abundant on each of the islands, which continued to decline over the 19^th and 20^th centuries, and there have been rapid declines in the wild subpopulations since the mid-1850s to the present (Lloyd 1846, Balfour 1879, Cordemoy 1895, Maunder et al. 2002). Average population decline over all the varieties compared to historic reporting of abundance is over 90% (Cordemoy 1896, Guého 1988, Maunder et al. 2002, Mauritian Wildlife Foundation 2012–2021).

The species Dictyosperma album and its varieties occurs in similar habitats across the Mascarenes. Generally known to inhabit low-elevation dry forest below 600 m in elevation, D. album varieties can be found at all elevation levels between 0–615 m (Maunders et al. 2002). The varieties can also be found in a range of soil and topography types, with D. album var. aureum being mainly found on coralline limestone and volcanic soil (Balfour 1879). Dictyosperma album var. conjugatum likely requires deep soil on the slopes of Round Island (Lambdon 2019), while D. album var. album is not limited to a particular soil type (Saliman-Hitillambeau 2020). Habitat quality and availability is limited within Mauritius, with only 2.4% of land area protected and 4.4% native forest left (Hammond et al. 2015). In Rodrigues, the combined effects of development, farming practices and invasive species have led to high levels of soil erosion and a decline in the quality of forests (Gade 1985, Bunce et al. 2008, Kirsakye 2015), La Réunion has also faced habitat decline, though not as severe as in Mauritius, with 30% of pristine habitat still available (Moyer 2001, Strasberg 2005). However, it does still face threats from invasive flora and fauna, human development and illegal harvesting, with the IUCN downgrading Réunion’s biodiversity status to having ‘significant concerns’ in 2017 due to the increase in invasive species cover (IUCN 2020). This highlights the continued need for sustained habitat restoration and preservation efforts in the Mascarenes region to be able to preserve this species.

This species is known to be quite variable, with the differences maintained in cultivation. Hybridization between the varieties is suspected, though not confirmed as of yet. The species can reach maturity and start flowering at 15–20 years of age, with fruits developing soon after (Mauritian Wildlife Foundation 2013, Mauritian Wildlife Foundation 2012–2021). Flowering time differs between the varieties. Flowering can occur anywhere between June and December, with fruiting generally occurring between January and March (Mauritian Wildlife Foundation 2012-2021, Mauritian Wildlife Foundation 2020–2022, Mauritian Wildlife Foundation 2020-2021), but can span a wider range of the year depending on the specific subpopulation.

This species and its varieties face similar threats, to different degrees of impact. All varieties are affected by invasive flora and fauna, as well as the effects that climate change will bring to the Southwestern Indian Ocean. Both D. album var. aureum and D. album var. conjugatum face extinction in the wild by a single event (e.g. intense cyclones, drought etc.). Both are also affected by potential hybridization with D. album var. album which may have an effect on current re-introduction programmes. Additionally, D. album var. album faces threats of illegal harvesting due to its importance to domestic trade within the Mascarenes, as well as the unmitigated spread of invasive flora and fauna.

Within the species Dictyosperma album, D. album var. album has been the most widely cultivated palm in the Mascarenes. In Rodrigues, D. album. var. aureum has been locally harvested for subsistence use, but not commercially cultivated. Due to the lack of human habitation on Round Island, cultivation or harvesting of D. album var. conjugatum for human consumption has not been historically recorded. The Ministry of Agro-Industry and Food Security (2016) has designated Dictyosperma album as a crop wild relative (CWR), with Dictyosperma album var. album and Dictyosperma album var. conjugatum, as priority taxa in its National Strategic Action Plan For the Conservation and Sustainable Use For Crop Wild Relatives.

Conservation work has been unequal among the varieties and the countries that oversee their management. However, this work has been slowly seeing success, with important habitat being preserved, propagation increasing and numerous re-introductions. Within Mauritius, conservation efforts for D. album var. album is overseen by the National Parks and Conservation Service and the Mauritian Wildlife Foundation, while D. album var. conjugatum is overseen by Durrell Wildlife Conservation Trust and the Mauritian Wildlife Foundation. In Rodrigues, conservation efforts for D. album var. aureum is also overseen by the Mauritian Wildlife Foundation, along with the Rodrigues Forestry Service. In La Réunion, conservation efforts for D. album var. album is overseen by Conservatoire Botanique National de Mascarin and the Parcs Nationaux de France. All varieties have some level of re-introduction regime occurring, as well as protection under Management Areas and restoration activities underway in surrounding habitat. Seed banking is underway for D. album var. aureum and D. album var. conjugatum, as well as invasive species management.