R Gordon of St Clair asks :-
Where are the seeds of the pussy willow and how are they dispersed?
Janice Lord, a botanist at the University of Otago, responded.
Pussy willow is the common name of Salix x reichardtii, the “x” denoting that it originated as a hybrid between two different species – S. caprea and S. cinerea.
All members of the willow family have separate male and female trees, i.e. they are dioecious. In spring both sexes produce catkins, which are elongated inflorescences containing many tiny flowers. The structure of a catkin is simple. Flowers are attached individually to a central stalk called the rachis and each flower has a single oblong bract at its base, which is often hairy.
Flower petals are reduced to one or two squarish to oblong “glands”, which are less than one millimetre long. Male flowers usually have two pollen-producing stamens. Female flowers have a single ovary and no stamens. The ovary matures into a dry capsule which splits in two, releasing vast quantities of minute seeds. Seed fall is not very conspicuous because as well as the seeds being tiny, they are released well after the leaves have expanded. Due to the small size of the seeds they are easily carried aloft by even light winds.
Pussy Willow is unusual in that the common name is usually only applied to the male plants, because only the male catkins are the real “pussies”, being compact and softly hairy. Female pussy willow trees do exist but as the catkins are more elongated and less hairy they don’t look like real “Pussy Willow”.