Trade-offs abound in nature. It would be impossible for any organism to evolve a combination of attributes that are ideal under all circumstances. This is especially true for plants. The botanical world’s need to obtain water and nutrients from roots while simultaneously maximizing photosynthetic area often means finding a balance between allocating resources to leaves and roots. This trade-off is made especially apparent in species like Panama’s basurera (Quadrella antonensis), whose name translates to trash basket.

The basurera is a rare treelet endemic to only a few highland locations in Panama where it grows in the dense shade of the rainforest canopy. It earned the name basurera because this tiny tree has adopted a litter trapping lifestyle. The few leaves it produces form a basket-like structure at the tip of its spindly stem. As debris falls from the canopy above, some of it is trapped by basurera’s leafy basket. The fact that basurera collects debris isn’t all that shocking. Many understory plants are saddled with a debris load to one degree or another. The most striking feature of its anatomy can be found by digging around in the litter trapped within its leafy basket.

Even “large” basurera are not that big. [SOURCE]

From its tiny stem and branches emerges numerous adventitious roots. These roots branch out into the humus as it builds up within the basket. Not only do the roots help the treelet to hold onto any litter that falls into the basket, they also function just like roots in the soil. As the roots branch and fork, they produce copious fine root hairs. These root hairs have even been found to associate with arbuscular mycorrhizal fungi! Indeed, the basurera is creating its own soil by trapping litter from above that it can use to obtain nutrients that it can’t get from the soil at its base. However, in using its leaves to do this, this treelet puts a damper on its potential photosynthetic capacity.

As humus develops within the basket, it blocks sunlight from hitting the leaves. As you can imagine, this creates a delicate knife-edge economy in this already shady habitat. By manipulating the amount of humus in the basket, scientists have shown that the basurera relies on that humus for sustenance. When the humus was selectively removed, basurera lack the nutrients needed to produce more leaves. However, as humus builds up, the plant photosynthesizes less and less. It would appear that this species has dealing with a trade-off in assimilating carbon and acquiring other forms of nutrients.

Adventitious roots emerging from the stem of a basurera. [SOURCE]

Research suggests that the shift towards litter trapping likely has to do with the nutrient-poor soils in which the basurera grows. Instead of relying on the ground to provide it with the nutrients it needs, the basurera simply produces its own supply of soil in its leaves. It seems that for this shade-tolerant treelet, obtaining nutrients is more pressing than maximizing photosynthesis. However, in doing so, it is sacrificing growth and reproduction. By studying 112 individuals over the course of a year, scientists found that only 30 basurera actually flowered and, out of those 30, only 10 fruits were produced. Such low reproductive output likely explains why this treelet can only be found in a few areas of Panama. It also makes the basurera extremely vulnerable to disturbance. With slow growth and even slower reproduction, the basurera is at high risk from anything that can reduce population numbers.

Despite its rarity in the highland forests of Panama, the basurera nonetheless offers a window into the economic balance plants must strike as they try to make a living. It just goes to show you that even small, obscure species have a lot to teach us about the evolution of life on our planet.

Photo Credits & Further Reading: [1]