A life of miniaturization
Mystropetalon thomii is a holoparasite, a plant that derives all of its nutrients from a host. It has no green chlorophyll for photosynthesis and spends almost its entire life underground as a tuber-like structure fused to the roots of various shrubs in the fynbos biome. This region, part of the Cape Floral Kingdom, has immense biodiversity, yet Mystropetalon thomii remains exceptionally inconspicuous. Its entire existence is reduced, shedding the need for leaves and stems in favor of a direct connection to its hosts.
The only part of the plant that ever breaks the soil surface is the inflorescence, a strange, brush-like structure that barely rises above the ground. These dark-red flower clusters are typically monoecious, meaning they contain separate male and female flowers on the same plant. In a strategy to prevent self-pollination, the female flowers mature before the male flowers do. Some inflorescences are purely female, a condition known as gynoecy. The genus Mystropetalon is considered monospecific, containing only the single species M. thomii. While other species were described in the past, modern analysis suggests the observed differences were merely variations within this one species. The plant is known in local Afrikaans as "Aardroos" (Earth Rose) or "Kaapsewolwekos".
An unusual reproductive strategy
The reproductive biology of Mystropetalon thomii is complex. The plant's low-to-the-ground flowers and nectar production suggested pollination by non-flying mammals. Field studies using camera traps confirmed this hypothesis, revealing that several species of rodents are frequent visitors. The animals are attracted to the nectar and scent, which are produced in greater quantities by the male-phase flowers, and they carry large loads of pollen on their snouts.
The plant is not dependent on them. Experiments where mesh cages excluded all animal visitors showed that the plant still successfully produced seeds. This indicates that M. thomii is capable of apomixis, a form of asexual reproduction where seeds are formed without fertilization. The plant welcomes its rodent pollinators but does not strictly require them to reproduce. Once the seeds are produced, they are dispersed by ants. The seeds possess a white, fatty body called an elaiosome, which attracts ants. The ants carry the seeds back to their nests to consume the elaiosome, conveniently planting the seed in a new location.