The Gibraltar Magazine

Urban Dwellers

Most of the 600 or so species of plants found on the Rock will be found on the Upper Rock, the East Side or the southern Flats. However a surprisingly large number will be found mainly in urban areas, growing from rooftops, walls, cracks in pavements, and as weeds in planted areas.

Perhaps the most notable and familiar of these is the snapdragon, Antirrhinum majus subsp cirrhigerum which is often seen on rooftops and ledges throughout town. The pink flowers are around 3 cm long, and grow in dense racemes.

Although the snapdragon can be found growing throughout the Rock, not just in town, the red valerian, Centranthus ruber, is only found in urban areas, especially on old walls. The tiny flowers may be white, pink or crimson and grow in dense clusters around 8 cm long. The petty spurge, Euphorbia peplus is the most common spurge found on the Rock. It grows not more than 25 cm tall, and will grow everywhere and anywhere it can, especially as a weed in planted areas, including flower pots. When the stems and leaves are broken, it releases a milky sap which is a skin irritant.

An insignificant but very common plant is the annual mercury, Mercurialis annua subsp ambigua. This plant will be found growing in all urban habitats including waste ground. The tiny greenish flowers have no petals and grow in small clusters, the male ones in long-stalked racemes and the female ones in the leaf axils.

The southern pellitory-of-the-wall, Parietaria lusitanica, is a delicate branching plant which is very rarely seen outside urban habitats. It grows on old walls and rock fissures, with stems 10 to 30 cm long. The flowers are tiny and grow in the leaf axils.Of the three species of stonecrop found on the Rock, the white stonecrop, Sedum album, is the only one that will be found in urban areas, in particular rooftops and old walls. The white to pale pink flowers grow in dense flat-topped clusters 10 to 15 cm tall. The fleshy cylindrical leaves are around 1 cm long and often tinged with red.

The chickweed, Stellaria media is generally a weed of planted areas, but can also be found elsewhere on the Rock. The white flowers are around 8 mm across, and the 5 petals deeply cut so that they seem to have ten petals. The spreading stems are up to 30 cm long.