Plant of the Day (December 16th, 2011) -Cymbalaria muralis Gaertn., Mey et Scherb.

Today's “Plant of the Day” is Cymbalaria muralis Gaertn., Mey. et. Scherb. from the Plantagninaceae (plantains) family. In some literature, this species still belongs to the Scrophulariaceae (figworts), but phylogenetic studies have proven, that it belongs to the plantains. The German name of this plant is “Mauer-Zimbelkraut” or simple “Zimbelkraut” (cymbal-weed), while in English, it is called “Kenilworh Ivy” or “ivy-leaved toadflax”.

C. muralis - habitus

It's a small herb, which grows on walls. The crawling and bald shoots are between 15 and 60 centimetres long (6 to 24 in). The leaves are kidney-shaped or heart-shaped (or a mix of them). They have a dark-green dorsal site, while the ventral site is often reddish (also the shoots).

The long-stalked flowers are cygomorph. Their petals are violet with a white bulge and yellow spots. They also have a long spur. This morphology was also the reason, why this species has belonged to the Scrophulariaceae in past (as for Linaria vulgaris Mill.).

C. muralis - habitus

The biology of pollination is also the same as with L. vulgaris. The function of the bulge is to attract pollinators like bees or hoverflies. However, the most interesting feature of C. muralis is the kind of spreading its seed. After pollination and ripening, the seed stays connected with floral-axis, which grows in a new dark place like a wall column, where the seed can start to sprout. This behaviour, the growth of the parts of a plant to dark places, is called “negative phototroph”, while the opposite is called “Phototrophism” (growing to light).

C. muralis - a shoot grows into a wall colum
(negative phototrophism)

Originally, this plant is native to the Mediterranean area but can also be found all over the world. Its original habitat were the slopes and rocks of the Mediterranean mountains, but later, C. muralis was brought to other countries as medicinal and garden plant and naturalized later. Today, you can find it on warm, sunny walls and similar places. C. muralis is also the characteristic species of a plant society on walls: the Parietarietalia judaicae