- fungal hyphae
The long, branching filamentous structures of a fungus that make up the mycelium and are essential for nutrient absorption and symbiosis with plant roots.
Urban soil compaction disrupts fungal hyphae, which impairs the symbiotic networks between trees and fungi critical for nutrient exchange.
- lateral roots
Roots that extend horizontally from the primary root (radicle) and serve to anchor the plant securely into the soil while also increasing the surface area for water and nutrient absorption.
In compacted urban soils, trees often produce lateral roots that spread beneath pavement and infrastructure, sometimes disrupting surfaces like calçada in Lisbon.
- leaf litter
The layer of dead plant material, such as leaves, bark, and twigs, that accumulates on the soil surface and contributes to nutrient cycling and habitat for decomposers.
In cities like Lisbon, leaf litter is frequently cleared for aesthetic reasons, reducing habitat for invertebrates and soil health.
- mulch
A layer of material applied to the surface of soil to conserve moisture, improve fertility, reduce weed growth, and enhance visual appeal.
Mulching is rare in Lisbon's street tree pits, even though it can protect roots and foster microbial life in urban soils.
- mutualism
A type of symbiotic relationship in which both species involved benefit from the interaction, often contributing to each other's survival or reproductive success.
In natural forests, mutualisms between fruiting trees and birds help spread seeds, but these interactions are often disrupted in urban environments.
- native
One that occurs naturally in a particular region, ecosystem, or habitat without human introduction, and is adapted to local conditions over time.
*Celtis australis* is native to the Iberian Peninsula and is well adapted to the Mediterranean climate and soils of Lisbon.
- perfect
Also known as a hermaphrodite flower, has both male (stamens) and female (carpels) reproductive structures and is capable of self-fertilisation or cross-pollination.
The flowers of *Celtis australis* are perfect, meaning each individual flower contains both stamens and pistils, enabling potential self-pollination.
- rugose
Wrinkled
The leaves of Celtis australis, the European nettle tree