Perrierosedum

Perrierosedum is a genus of succulent plant in the family Crassulaceae containing only one species, Perrierosedum madagascariense. It is a critically endangered species endemic to Madagascar.^[2]

Perrierosedum
Conservation status
Critically Endangered  (IUCN 3.1)[1]
Scientific classification
Kingdom:	Plantae
Clade:	Tracheophytes
Clade:	Angiosperms
Clade:	Eudicots
Order:	Saxifragales
Family:	Crassulaceae
Genus:	Perrierosedum (A.Berger) H.Ohba
Species:	P. madagascariense
Binomial name
Perrierosedum madagascariense (H.Perrier) H.Ohba
Synonyms[2]
Sedum madagascariense H.Perrier

Taxonomy and history

Sedum madagascariense was described by French botanist Joseph Marie Henry Alfred Perrier de la Bâthie in 1923. S. madagascariense was placed in Sedum section Perrierosedum, named in honour of Perrier de la Bâthie, in 1930 by Alwin Berger.^[3] Sedum sect. Perrierosedum would later be elevated to genus by Japanese botanist Hideaki Ohba in 1978, re-designating the species Perrierosedum madagascariense.^[4]

This species is known as maroatody in Malagasy.^[1][4]

Distribution and habitat

P. madagascariense is known only from Andringitra Massif in the Haute Matsiatra and Ihorombe regions of south-central Madagascar. It grows on rocky outcrops at altitudes of 1,600 m (5,200 ft) to 2,659 m (8,724 ft).^[1]

Description

P. madagascariense is a small perennial shrub growing 50–80 cm (20–31 in) tall. The branches are hairless and quadrangular. The fleshy leaves are sessile, borne opposite one another, measuring 2.5–5 cm (0.98–1.97 in) by 1.5–2.5 cm (0.59–0.98 in) with finely toothed margins. The inflorescence is a terminal corymbose cyme bearing three to ten flowers. The flowers measure approximately 10 mm (0.39 in) across and are hexamerous or, rarely, pentamerous. The petals are white with a red to orange tint and purple veins.^[4][5]

Conservation status

P. madagascariense is listed as critically endangered by the International Union for the Conservation of Nature under criterion B2ab(iii), based on its small area of occupancy and the decline of its habitat. It is known only from a single location within Andringitra National Park, and the size of the population is unknown. Despite occurring within a protected area, it is threatened by wildfires, grazing, and human disturbance from hikers and rock climbers.^[1]

This species has been planted at the Botanical and Zoological Garden of Tsimbazaza in Antananarivo, Madagascar.^[1]