[2][3] The guano, and since the 1950s also the rock and sand into which the phosphate had been leached,[2] were mined away between 1906 and 1972 converting an island once densely forested to the current barren, pitted landscape.

[2] St. Pierre has a gently sloping seabed on the exposed southeastern coast and a steep drop off on the northwest, where the fringing reef is all but absent.

[4] Today the island is barren except for a clump of Casuarina equisetifolia trees up 12 m (40 ft) high on its northwestern part, covering a third of the land area.

Most of the plant species once found on St Pierre are now gone, including the Pisonia, Suicide Tree (Cerbera odollam) and rosemallow (Hibiscus tiliaceus).

[2] By about 1960, it was noted that the most common herbaceous plant was Stachytarpheta indica, while the introduced Indian Blanketflower (Gaillardia pulchella) had established itself widely.