The cornus are a big family, commonly referred to as dogwoods. In our climate where we can grow most plants, cornus are not as widely featured as in other areas of the world because we are really too damp and too mild for most of them. They perform much better in a drier, continental climate with hot summers to ripen the wood, sharp seasonal change to trigger the autumn colours for which many are renowned and a good winter chill. Our C. kousa has had its hiccups in life (dieback threatened it a couple of years ago, possibly due to wet roots) but it battles on and in early summer the pink and white flowers are a seasonal delight, albeit a little brief. The welcome rain this week shortened its season.
Curiously, the flower is actually the dull, nubbly bit in the centre. What look like four pink and white petals are actually bracts – in other words specialised leaves which protect the flower buds, so not petals at all. This is common to all the dogwoods and to many other plants as well, including lacecap hydrangeas. Kousa is common in Japan and also found in Korea but Glyn Church tells me the form we grow in New Zealand is actually the one from central China, collected in 1907. After several decades, ours is a narrow, columnar tree about six metres high. When we were last in England, we saw many hybrids between C. kousa and C. nuttallii, some with spectacular, large flowers which were very showy indeed. Kousa shows resistance to anthracnose which has decimated the cornus display overseas and the new hybrids are, in part, an attempt to breed resistance to the disease.