Pollination of Haworthias

Paul Forster

After reading the article of the same title by David Hutchinson in the October 2001 Haworthiad, I thought that my own method of pollinating haworthias might be worth description.  Initially I tried spines or thin bits of dry grass to transfer pollen; however, little or limited success was achieved with these tools.  I am now having excellent success with the following tools and process.  First, wait for the flowers to properly open.  Many haworthias partially open flowers for the first day, but by day two the corolla is fully open and pollen release is occurring.  I haven't experimented with time of day, as the pollinating generally gets done when I have spare time (a precious commodity).  Seed set has been successful with pollinating undertaken in the morning, midday, afternoon or evening.  Secondly, once you have selected the plants to be pollinated, go through all the fully open flowers and remove the lower three petals by hand.  This exposes the style and six stamens (anthers and filaments) and lets you see what is going on.  I use an American made Optivisor with a x10 lens (this is a headset with adjustable flipdown magnifying lens), several pairs of fine-tipped forceps (dissecting forceps), a couple of tissues, and a bottle of methylated spirits.

Remove all the stamens from the first plant with a pair of forceps and wipe them off on one of the tissues taking note where you have placed them.  Then you can remove stamens from a second plant with a second pair of forceps and rub the pollen directly on the style head.  I usually take two or three stamens at a time, unless there is a paucity of them and a lot of flowers to pollinate.  You can then reapply the first pair of forceps and the stamens from the first plant to pollinate the flowers on the second.  The forceps are sterilized by placing them in a glass full of methylated spirits, then wiping them dry.  After that you just let nature take its course.  I would add that all my pollinating is undertaken in a screened sunroom where the plants are left for days or several weeks until I am finished with them.  This way, no errant insects get in ahead of you.

If you want to pollinate different flowers on the same inflorescence with different pollen, you have to label the individual flowers or parts of the inflorescence.  This can be done by making small knots of coloured cotton around the parts and recording the details.  If pollination is successful, this is usually obvious within a week.  Regular observation is necessary to ensure that you don't lose the seed when the fruits are ripe.  Some growers place short pieces of plastic drinking straws over the fruit to keep the three parts together.  I have also seen them sticky taped together although this is messy when you have to get the seeds out.  Using the above methods I have successfully set seeds on a wide range of haworthias, although not with the proficiency of small native Australian bees of the genus Trigona that seem especially designed for haworthia flowers.  Undoubtedly, similar small bees effect pollination of these plants in southern Africa.