Palmiste marron  (Hyophorbe verschaffeltii)

Classified as Critically Endangered (CR) on the IUCN Red List (1).

The palmiste marron is a solitary palm with a distinctive grey, spindle-shaped trunk that bulges in the middle (2) (3) (4) (5) and has ring-like markings (6). A smooth, waxy, bluish-grey crownshaft, up to 90 centimetres tall and swollen at the base, emerges from the top of the trunk (2) (4). The leaves of the palmiste marron are large, at 1.8 to 3 metres in length, and pinnate, with 30 to 50 pairs of rigid, dark green leaflets which measure around 60 to 80 centimetres in length (2) (3). The leaf stalk is yellow (3).

The palmiste marron is endemic to the island of Rodrigues, in the Indian Ocean, where it occurs in only 17 locations, including Grand Montagne, Anse Quitor and Ravine de la Cascade, St Louis (1) (5) (7) (8).

This palm is reported to occur in scrub forests and savannas, and to grow in limestone areas (1) (2).

The palmiste marron is monoecious, bearing both male and female flowers on the same plant (2) (3) (4) (8). The yellow flowers are unisexual (each flower possessing either male or female reproductive organs) and arranged in inflorescences that emerge from long, upward-pointing, horn-like bracts on the upper part of the trunk (2) (3). The flowers are said to have a sweet, delicate fragrance (6). The fruit of the palmiste marron is a rounded drupe, 2.5 centimetres wide, and is black when ripe (2) (3) (5).

Although widely cultivated as an ornamental palm (1) (5) (7), the palmiste marron is the second rarest palm on Rodrigues, with fewer than 60 individuals left in the wild, and little if any natural regeneration occurring on the island (1) (7) (8). The main threats to the species are overgrazing by cows, sheep and goats, as well as invasion by non-native plants, high levels of seed predation by rats, and severe fragmentation of the population (1) (7) (8). With such a tiny population, events such as cyclones can also have catastrophic effects on this palm (8). Although the palmiste marron is being increasingly cultivated on Rodrigues, to be planted as part of a habitat restoration project, there is a threat of hybridisation with Hyophorbe lagenicaulis, which has been introduced from Round Island (1) (7) (8).

Conservation measures recommended for the palmiste marron and other endemic palms of the Mascarene Islands include fencing and weeding of areas of native forest to protect the remaining wild palms, as well as propagating species and re-introducing them into the wild, and undertaking further biological research (7) (8). It will also be important to involve local communities, with education programmes, incentives from tourism and palm plantations, and stricter laws for cutting down palms (7). The palmiste marron needs to be protected from hybridisation with closely-related palm species, and legislation is needed to ban the introduction of non-native palms to Rodrigues. Palms that have already been introduced will also need to be removed, although this has proved difficult to date because most are being grown in private gardens (7). Without a long-term conservation programme, this unique and Critically Endangered palm is in great danger of becoming extinct in the wild (8).

To find out more about palms and their conservation see:

• Fairchild Guide to Palms:
  http://palmguide.org/index.php
• IUCN Palm Specialist Group:
  http://www.iucn.org/about/work/programmes/species/about_ssc/specialist_groups/directory_specialist_groups/directory_sg_plants/palm_sg/
• Palmweb:
  http://www.palmweb.org/