Right now, karaka trees are fruiting heavily. But not all of them. Some trees are covered in fruit and others have none or very few. Some years ago, I wondered if this meant they had separate sexes, and was able to show that this is the explanation (Garnock-Jones et al. 2007). Male trees do produce a few fruits, so the sexual system in karaka is best described as gynodioecy (some plants strictly female; others are inconstant males).
Here are the two trees that started this research off, photographed this month in Kelburn.
|Karaka trees in fruit, Kelburn, Wellington, 2014|
Here are the same two trees about 10 years ago.
|Karaka trees in fruit, Kelburn, Wellington, 1998 (from Garnock-Jones et al., 2007)|
On the female tree, the panicles fruit heavily, with many of the flowers (but by no means all) developing fruits.
|Fruits on a female karaka tree|
On males, usually a single fruit develops on each of a few panicles.
|Fruits on a male karaka tree|
|Karaka flowers. On a female tree (left); male tree (right)|
Garnock-Jones PJ, Brockie RE, FitzJohn RG 2007. Gynodioecy, sexual dimorphism and erratic fruiting in Corynocarpus laevigatus (Corynocarpaceae). Australian Journal of Botany 55: 803–808.