niggerhead

We were sailing swiftly along on a calm and glassy sea, past beautiful headlands and bits of scenery clothed with vivid and luxuriant green down to the water's edge; past glistening coral islands, on whose outer edges pale green billows broke on the white sandy beaches, boiling and seething as they dashed against a row of ugly "nigger heads," as the rocks were called, dotted here and there.

These plants fill the interstices between the grasses and tiny shrubs that make the outer, fuller form of the niggerhead.