In South Africa, Klepiel & Johnson have found that the Natal Crocus, Apodolirion buchananii, has combined a strange combination of rapid reaction and slow growth in its reproductive cycle. They observed the plant blooming right after grassland fires in winter, yet the fruits grow underground, taking over half a year to mature. The combination of fast and slow allows the plant to take advantage of the best conditions in both phases of its reproduction.
While Apodolirion buchananii isn’t an actual Crocus, the authors say it gets its common name Natal Crocus because, like a crocus, the plant flowers before it produces its leaves. After a fire, the plants produce sweet-smelling flowers that range from white to light-pink and emerge just a few centimetres above the soil. The main scent of the flowers comes phenylacetaldehyde, a chemical that attracts many species of bees. Attracting pollinators is critical, as the plant cannot self-pollinate. Without pollinators, there is no next generation.
After successful pollination, the developing fruit stays hidden underground for 30 weeks while it matures. The ripe fruits finally push up through the soil during the peak of summer rains. Once the fruit splits open, over six months of preparation turns into a frenzy. Ants enter, and examine each seed carefully with their antennae before picking it up and carrying it to their nest.
This is rapid work. Within 24 hours of the fruit opening, ants typically remove all the seeds. Rapid action is necessary, because the seeds germinate fast, usually within just a few days. By getting carried by the ants, the seeds ensure they get buried in favourable conditions.
What is puzzling is why the ants do this. Klepiel & Johnson note the seeds do look a bit like the ant larvae of Myrmicaria natalensis. When ant nests are disturbed, worker ants have been seen carrying both seeds and their own larvae to safety. It seems that, at least for a short while, the seeds are easily confused with larvae.
Kiepiel, I., & Johnson, S. D. (2024). Scent‐mediated bee pollination and myrmecochory in an enigmatic geophyte with pyrogenic flowering and subterranean development of fleshy fruits. American Journal of Botany. https://doi.org/10.1002/ajb2.16421 (OA)
