Spiky objects found beneath trees often spark curiosity about their origin. These common tree droppings are examples of how plants interact with their environment and perpetuate their species. This article explores their identity, biological function, and practical considerations.
Identifying Common Spiky Tree Droppings
One common spiky dropping is the fruit of the sweetgum tree (Liquidambar styraciflua). These woody, spherical capsules, known as “gumballs,” are typically 1 to 1.5 inches in diameter and covered in sharp points. While sweetgum trees are valued for their star-shaped leaves and vibrant fall foliage, their abundant spiky fruits are often considered a nuisance.
Another common spiky object comes from the horse chestnut (Aesculus hippocastanum) or related buckeye species. The fruit is a green, fleshy, somewhat spiny husk that encases one to three large, shiny, dark reddish-brown seeds, often called conkers. These husks split open upon falling, revealing the smooth seeds within.
Sycamore trees (Platanus species) produce distinctive globular seed balls. While not as sharply spiky as sweetgum fruits or horse chestnut husks, they have a rough, textured surface. These balls are dense clusters of small achenes, each with fine hairs for wind dispersal. They often hang from branches through winter, breaking apart to release seeds in spring.
Beyond fruits and seed pods, abnormal growths called galls can also appear spiky and fall from trees, particularly oak trees (Quercus species). Oak galls form from the tree’s reaction to chemicals secreted by insects, most commonly gall wasps, or sometimes fungi. These vary widely in appearance, with some appearing as hard, spherical, and sometimes spiky structures on twigs or leaves.
Purpose of the Spikes
Spikes on these botanical structures serve several biological functions, primarily for protection and seed dispersal. They act as a defense mechanism, deterring herbivores and other animals from consuming immature fruit or seeds before dispersal. This protection helps ensure seeds fully develop, increasing the plant’s reproductive success.
Once mature, spikes also aid in seed dispersal. For some fruits, sharp points allow them to attach to animal fur or feathers, transporting them to new locations. In other cases, the spiky outer layer may aid in rolling the fruit away from the tree, or breaking open upon impact, releasing seeds. This helps plants spread their offspring and colonize new areas.
Potential Hazards and Handling
While natural, these spiky tree droppings can pose hazards, especially in areas with people or pets. Sweetgum balls create a tripping hazard on sidewalks and driveways because they are hard and roll. Stepping on them barefoot can be painful and may cause ankle injuries.
Toxicity is another concern, especially with horse chestnuts. All parts of the tree, including seeds (conkers) and leaves, contain toxic compounds called glycosidic saponins. Ingestion by humans or pets can lead to gastrointestinal upset, causing vomiting and diarrhea, and in larger quantities, more serious symptoms, including loss of coordination, muscle spasms, or paralysis. While deer may consume conkers without ill effect, they are harmful to dogs, cats, horses, cattle, and chickens.
When managing these spiky droppings, wear sturdy shoes to prevent injury. Use gloves for collection to protect hands from sharp points. Regular raking or sweeping helps clear them from pathways and lawns, reducing tripping risks. Some property owners opt for growth-regulating injections for sweetgum trees to reduce fruit production.