Capparis spinosa L. is a perennial eremophyte shrub, widely distributed in Mediterranean
Europe: in Italy it is commonly found as a ruderal species growing on and covering walls of the
cities. Its highly developed root and xylem systems are the reason of its ability to survive in
both cold and heat stressed environments, as they confer the plant the capability of using the
groundwater resources (Yin et al., 2014) and the ability of growing on very dry spots, like walls
and rocky coastal areas (Kulisic-Bilusic et al., 2010).
We analysed the spontaneous volatile emission of different aerial parts of caper (Capparis
spinosa L.) by means of HS-SPME-GC/MS. The samples included leaves, buds, sepals, seeds,
fruits, pistils, stamens, petals and flowers; they were randomly collected from specimens
growing as wild, ruderal plants on the medieval walls of Pisa (Italy).
We identified 178 different compounds of which, in different proportion based on the type of
sample, the main ones were (E)-β-ocimene, methyl benzoate, linalool, β-caryophyllene, α-
guaiene, germacrene D, bicyclogermacrene, germacrene B, (E)-nerolidol, isopropyl
tetradecanoate and hexahydrofarnesyl acetone.
We carried the multivariate statistical analysis of the results, with both the HCA (Hierarchical
Cluster Analysis) and PCA (Principal Component Analysis) method. The analyses seem to
point out that the parameter leading the emission patterns is the function of the studied sample:
the flowers samples showed differences in the emission profile between their fertile and sterile
portion, and between the other parts of the plant. The green parts emission profiles group them
together in a cluster of their own and they are different from those of seeds and fruits.
Furthermore, we hydrodistilled caper fully bloomed flowers and analysed its composition.
Literature reports analyses of the essential oil of caper seeds (Ara et al., 2014; Yin et al., 2014),
fruits (Afsharypuor et al., 1998; Yin et al., 2014), roots (Afsharypuor et al., 1998), leaves
(Afsharypuor et al., 1998) and floral buds (Kulisic-Bilusic et al., 2010). The bloomed flowers
essential oil volatile profile significantly differs from those of the essential oils obtained from
other parts of Capparis spinosa reported in the literature: it is the only volatile oil rich in
oxygenated sesquiterpenes (mainly (E)-nerolidol and (E)-nerolidol acetate) and oxygenated
monoterpenes (mainly linalool)