Rarely of natural origin, more often created by people for the purpose of delimiting crops or pastures and sometimes used for the production of wild fruits (hazelnuts, blackberries), also in connection with bird trapping activities, hedges are an unmistakable element of the traditional rural landscape.   

Hedges may differ considerably in their floristic composition, but their basic structure is always made up of medium-sized shrubs and trees that are usually pruned periodically.  

The hedges of the Trieste Karst can be traced back to three main types:  

• pioneer dog-cherry hedges (Frangulo rupestris - Prunetum mahaleb)  

• privet and bramble hedges (Rubo ulmifolii - Ligustretum vulgare)  

• snowdrop hedges (grouping with Corylus avellana and Galanthus nivalis).  

The former, thermophilous, are characterised by pioneer shrub species typical of the karst ‘grize’, (screes) such as dog cherry (Prunus mahaleb), rock buckthorn (Frangula rupestris), common juniper (Juniperus communis), common bramble (Rubus ulmifolius) European smoke-bush (Cotinus coggygria), and spiny asparagus (Asparagus acutifolius), associated with typical elements of the Karst scrub such as manna ash (Fraxinus ornus), downy oak (Quercus pubescens), hop-hornbeam (Ostrya carpinifolia), and Montpelier maple (Acer monspessulanum). 

The privet and bramble hedges appear as a dense tangle of thermophilic shrubs, including privet (Ligustrum vulgare), dogwood (Cornus sanguinea), field maple (Acer campestre) and common bramble (Rubus ulmifolius), accompanied by lianas species such as ivy (Hedera helix) and old man’s beard (Clematis vitalba). Locally they are known as ‘graie’.  

Snowdrop hazelwoods, typical of cool environments, are thought to have originated for the most part from the cutting of the doline forest, of which they formed the edge. They therefore appear as a dense thicket dominated by the hazel (Corylus avellana), accompanied by field maple (Acer campestre), cornelian cherry (Cornus mas), dogwood (Cornus sanguinea), flowering ash (Fraxinus ornus), ivy (Hedera helix), blackthorn (Prunus spinosa) and elder (Sambucus nigra); grasses include the snowdrop (Galanthus nivalis), hellebore (Helleborus multifidus subsp. istriacus), the common primrose (Primula vulgaris), the black bitter-vetch (Lathyrus niger), European wild ginger (Asarum europaeum), and Jupiter's distaff (Salvia glutinosa).  

In the lowlands, the territories most strongly altered and compromised by human activities, hedges, where they have not been wiped out by excessive agricultural exploitation, fulfil the irreplaceable role of oases of refuge for numerous plant and animal species, for which they have the role of authentic ‘biological reservoirs’.