Two in One
Pelargonium 'Mr Wren' is a "collectors" pelargonium. It was found, I believe, as a sport in someone's garden, where it grew as a branch off of a red flowered plant. It is a lanky tall growing plant, but the flowers are unique. Each red flower petal is bordered by a white edge that looks as if it were painted on. If it were a simple genetic trait, this pattern would be worth repeating in other color combinations, but progeny of Mr. Wren will produce mostly red flowered offspring, and none will have Mr. Wren's pattern. This is because Mr. Wren is a chimera, a plant with two separate kinds of cell lines in its makeup. It is literally two plants in one. Some years ago, while doing the literature search for my thesis, I came across an study where the researchers separated the cells of the flowers of Mr. Wren and regenerated plants from individual cells taken from the petals. Cells from the white portion only grew white flowered plants, while cells from the red portion produced red flowered plants. Apparently the two kinds of cells coexist in a pattern which is maintained by the meristem (growing tip) of the plant. Even so it is not uncommon for an all red flower cluster to appear on a branch of Mr. Wren. If so, that branch needs to be pruned off, and the branches bearing the typical flower pattern retained.